Hands on 1985 Spring

an sElectronics From the Publishers of Rzdio- Electronics $2.50 U.S. SPRING 1985 $2.95 CANADA 48784 #4 THE MAGAZINE FOR THE ELECTRONICS ACTIVIST! SPACE TECHNICIANS SERVICE THE SATELLITES! tell you what went on up there! We = ,. GERNSBACK _ R. Communications and Interface Port for the ZX81 Build an Antique Shortwave Radio that works! Inside Digital Logic Circuity--a short course Battery/Alternator Monitor checks out your car 04 o 718 °6 487 Plus Budget C -to -V converter Match your own 1% resistors Test solar cells like the pros Infrared remote /control transmitter TEK PORTABLE OSCILLOSCOPES THE ANSWER BY ANY MEASURE You can't judge a scope by its cover. When you look at our simplified, practical internal design. you see why the Tek 2200 Series delivers unparalleled high performance and reliability in the field. You get quality that's unmistakably Tektronix In scopes so advanced, they cost you less to buy and own. Through an innovative new concept in scope design we reduced the number of mechanical parts by 65 %. Reduced cabling by 90 %. Virtually eliminated board electrical connectors. And eliminated the need for a cooling fan. The result: a scope with designed -in simplicity that increases reliability as it cuts downtime and repair costs. All of which means outstanding value in a compact, lightweight package that your service technicians will appreciate. Plus, you get a selection of performance to precisely match your needs. There are the 60 MHz single time base delay 2213A at $1200* and the 60 MHz dual time base 2215A at $1450` And at 100 MHz, the dual time base 2235 at $1650* and the 2236 with an integrated counter /timer/ multimeter at $2650" The industry's first three-year now in downtime, in service, in back -up scopes. On the bottom line, a Tek 2200 Series scope will save you money, time and trouble now and in the years to come. Contact your Tek Sales Engineer for a demo today. Or call 1- 800-426 -2200, Ext. 201. In Oregon, call collect. (503) 627 -9000, Ext. 201. warrantyt is testimony to 2200 Series dependability. Adding value to value are a variety of optional service plans that can economically extend this coverage to five years. Consider what you're paying CIRCLE 413 ON FREE INFORMATION CARD 'Paces FOB Beaverton. Oregon t3 -year warranty includes CRT and applies to 2200 family oscilloscopes purchased atter /1/83 Scopes are UL listed. CSA and VDE approved 1 Copyright it 1984. Tektronix. Inc All rights reserved TTA -517 Tektronix MT TEO TO EXCELLENCE cs Volume 2, No. 4 Spring, 1985 FEATURES 22 73 79 Space Technicians Service the Satellites -the details about the first service call in space Digital Fundamentals /Logic Circuits -discover the operation of five digital logic- circuit elements BCB Antennas for Small Lots -you get more wire for your space PROJECTS YOU CAN BUILD 32 40 45 49 53 59 82 to V Converter -measure capacitance with your digital voltmeter Solar -Cell Tester -test for the characteristics that count Cross Match One -match resistors to less than percent Auto Battery Alternator Monitor sparkling idea for your car Infrared R C Transmitter -remote touch -tune your TV Build an Antique Shortwave Radio-an old idea with new parts Shutter -Speed Tester-your oscilloscope checks your camera C 1 -a COMPUTER COVERAGE 65 87 94 -a Add an RS -232 Port to Your ZX81 cheapie comes out of the closet Make Your Budget Printer Valuable-easy retro -fits discussed Friedman on Computers- saving on disk drives MINI -PROJECTS 35 36 Yelping Siren -two oscillators against each other Low -Power Audio Amp -plug in the Yelping Siren and stand back SPECIAL COLUMNS 56 58 93 95 Jensen on DX'ing-tuning in the Pacific nations Testbench Tips-your fresh ideas are worth money Saxon on Scanners -pull -in the aero-action Calling All Hams-go up instead of out with a vertical DEPARTMENTS 2 4 8 14 Editorial -we talk about you this issue! Letters -here are some interesting ones New Product Showcase-look at all these goodies Bookshelf roundup of what's new -a 1 A. Second -Class postage pending at New York. S. He went on. Inc. Printed in U. were hobbyists just like you. bank. Charlie. New York.00. 200 Park Ave. we read it first for enjoyment. Martin. guess you know now the major criteria for inserting a particular project into Hands -on Electronics-the editor wants to build it himself! We are just like you.S. living somewhere in California. production manager Robert A. techniques and scientific and technological developments.A. Larry Steckler NATIONAL ADVERTISING SALES Joe Shere 1507 Bonnie Doone Terrace Corona Del Mar. That's our prerogative. KA2GUN Editor P. (ISSN 0743-2968) Published quarterly by Gernsback Publications. production associate Karen S. All rights reserved.S. CET. and when wire it in the afternoon.50. One -year. So devote this editorial to Charlie D. KA2GUN editor Carl Laron. we then begin to look deeper. Hands-on. You see. Canada $13.Electronics publishes available plans or information relating to newsworthy products.addressed envelope must accompany all submitted manuscripts and or artwork or photographs if their return is desired should they be rejected. when the project is finished will it impart practical experience on the builder that will improve his overall hobby activity? I'll stop here because don't have the six pages that Charlie had. Because of possible variances in the quality and condition of materials and workmanship used by readers. CA 92625 714:760-8697 Hands -on Electronics. if we enjoy the manuscript. Charlie. Do all hobbyists have lumps of solder embedded in their pants as do? I Cover photo by Walter Herstat Composition and interior design by Mates Graphics TT Hugo Gernsback (1884 -1967) founder M. I I I I I I Julian S. "Will many of our readers want to build this project? Are the parts easy to obtain? Are the parts inexpensive? Is the circuit so critical that should wire it in the morning. our selection process for articles is not as complex as you believe. Fishman. you see! And. When we read a manuscript. production assistant Jacqueline P. publisher Art Kleiman. most editors would have trouble walking across a room if they had to think about it! In the same manner. Charlie. subscription rate U. Lowndes. many weeks ago.. Fenton. and on -for six typewritten pages telling me my inner thoughts..associate editor Brian C. 2 .S. to be honest with you. it will work. NY 10003. circulation director Arline R. We ask some basic questions like. Yee. As a service to readers. it won't work ?" But most important. Inc. Weaver.EDITORIAL PAGE #4 The Magazine for the Electronics Activist! We SPRING 1985 get letters! received a letter from a reader who claims that he knows our thinking on how we select construction articles for Hands -on Electronics. editorial director Julian S. four issue. NY and at additional mailing offices. while preparing it for you. Subscription orders payable in U. and possessions $10 00. Martin. Harvey Gernsback Vice President. U. A stamped sell. c 1985 by Gernsback Publications. W. advertising coodinator BUSINESS AND EDITORIAL OFFICES Gernsback Publications. we work at a job that is play to us! So start thumbing through this issue and start enjoying it as we did.S. Harvey Gernsback. Hands-onElectronics disclaims any responsibility for the safe and proper functioning of reader -built projects based upon or from plans or information published in this magazine. We disclaim any responsibility for the loss or damage of manuscripts and or artwork or photographs while in our possession or otherwise. Tucker.S. New York.S. single copy price $2. all other countries $17 00. 200 Park Avenue South. production assistant Dianne Osias. funds only international postal money order or check drawn on a U. and on. editor -in -chief Larry Steckler.A. Inc. with one big exception. associate editor Ruby M. NY 10003 President: M. . : I Q 2 - Q Z 4 w > Dept.. 11111111111 1164 RUSH me free facts and full information on how I can study at home for the career I have chosen understand I am under no obligation and no salesman will visit me. Fold page again.. WMS55 O 2 w Name Age cr Address City State Zip Phone No ( 1 . vital in every aspect of our lives industry... equipment..Making Careers Below HOME STUDY MAKES IT EASY TO START! Theres no need to quit your lob or take time from your family or friends. We start you at the very beginning. whatever it takes to give you a total understanding of each sub Z lest or experiment. Everything w you need to complete your training-books. . 0' explain Your lessons are clearly written á and fully -illustrated with photos. everything step -by -step. And you never miss a paycheck But you are not alone. if you ever need a better understanding of something in your lessons.NOW YOU CAN TRAIN FOR A GREAT CAREER IN ELECTRONICS RIGHT IN YOUR OWN HOME. the years of biggest demand for consumer and industrial products.Demand Fields Of The 80's! .. Get In On The "Boom Years "! Electronics And Microcomputers Are The Big. business. Both North American and International Correspondence Schools are Accredited Members of the National Home Study Council in Washington D. You waste no time traveling to class or standing in registration lines. Yes.the time of greatest opportunity for job advancement. included with your ág testers course at no extra cost cr AP FIRST FOLD HERE when you mail this ENTIRE Postage -Paid ad NO POSTAGE NECESSARY ° To w 1..Or Train For One Of 32 Other Money. even in the home -it's easy to see why the future of electronics has no place to go but UPI i -is FIRST FOLD HERE - microcomputers become more charts. CHECK ONE BOX ONLY.. d Mail -Fold ad in following manner: Remove entire pagetear out or cut on dotted line to left 2. diagrams. lessons. As an CS student. the jobs are there and there's money to be (made.. Already many employers are offering top salaries and bonuses to attract the most qualified people. just phone or write to us and one of our instructors will get back to you with a detailed answer you know the Department of Labor predicts a 40°ío increase in jobs for Electronics Technicians over the next ten years! And those with specialized training in microcomputers will have the same kind of opportunities! Just imagine! Those who start now and get in on these great careers will witness the "boom years" of Electronics. examples. Fold page in half on 1st fold lines 3.C.. you learn at home. the hours you choose.but only for those with knowledge and skills-the kinds of skills gained through specialized training. Tape or glue the 3 open sides and drop in the mailbox today. on 2nd fold lines 4. Although your lessons are especially written for home study. TWO -YEAR TECHNICAL TWO -YEAR BUSINESS DEGREE PROGRAMS DEGREE PROGRAMS I Q o- w Z w Mechanical Engineering Technology Civil Engineering Technology Electrical Engineering Technology Electronics Technology Business Management Accounting Marketing Finance CAREER DIPLOMA PROGRAMS Microcomputer Repair Basic Electronics TV VCR Repair Computer Programming Air Conditioning & Refrigeration Electrician Police Sciences' Art High School Small Business Management Wildlife Forestry Conservation' Catering Gourmet Cooking Diesel Mechanics Auto Mechanics Gun Repair' Bookkeeping' Motorcycle Repair' Hotel Restaurant Management Surveying 8 Mapping Drafting' Small Engine Repair Veterinary Assistant' Fitness 8 Nutrition Travel Agent' 'These courses are offered by North American Correspondence Schools. And as electronics and Did HANDS -ON TRAINING AND EQUIPMENT INCLUDED WITH COURSE The great thing about your train ing is that its so complete... 1 BI POLAR LED FOR St 70 LED HOLDERS KEY ep 6 KEY WO PIECE HOLDER FE OR JUMBO LED 10 FOR 654 200 FOR 51000 CONTAINS 6 SINGLE -POLE NORMALLY OPEN SWITCHES MEASURES 4 1/4" LONG nilMAKE LED A FANCY INDICATOR CLEAR 4 FOR S1. (on -on) .D. But. someone is playing an electronic piano by battery that is recharged by a solar panel. TN I $1. That's it! Two readers 60 SII RINGER CONTROL OI 211272E 02 TIE 111 TO TELEPHONE LINES O RS WOK PT O ISO LATOR TEMPO u CS 22 10 RS SPKR In 170K VOLUME 56$11 LETTER SWITCHES 2S 21 o 23 ó B C UI AY 3 13M MELODY SYNTHESIZER R9 IHK PITCH C2 475F S IS I o 20 00 19 O.c1.D. The 3 -volt boost for input volt.000 mfd." have replaced the 7805 twice and the circuit is identical to what I've seen in Hands -on Electronics many times over.INTERLOCKING SAME AS ABOVE.1A1n1-1-aRI7(IN CALIFORNIA: 1 -800 258-6666) INFORMATION 1213) 300. It's just got to be! Nevertheless. PC LUGS.ILL# 22 44 PLATED SOLDER TYPE SUB-MINIATURE CONNECTORS USED FOR COMPUTER HOOK UPS. never mind! Your You may want to add an audio amplifier problem lies with the battery voltage.50 EACH 3 .- $2. cross out the S13 in the upper left in the drawing and insert an S12 above the words "RINGER CONTROL" to the immediate left.O. I'll bet it'll take care of the tied the unused inputs to a hi ( + 5 V).50 EACH :. 60 VDC 13/8'DIA Let the Sun Shine In don't believe it! was told that there is a solar -power piano.75 $4.000 mfd. I'm problem.S0 14.00 S3 00 MINIATURE TOGGLE SWITCHES ALL ARE RATED S. WY I don't dare. I was told that all it takes to power the circuit is light from a 75 -watt bulb or direct sunlight.told that should do that through a 1K age holds true for all 78XX and 79XX DC resistor. look at the size of the B. the melody synthesizer IC. Come on guys. Boulder.25 EACH CLEAR CLIPLITE HOLDER / 5 $1. What could be wrong? No -it's not the circuit because it erred.50 GREEN 10 FOR $2.50.. Pensacola. 22 /44 GOLD CONTACT SPACING $2. The solar cells were installed in the mid -sixties. PA 19134 for only $29. and can't for the life of me believe that someone would buy a piano that can be played only in the sun or under a strong light. Philadelphia..00 EACH CONTAINS 5 SINGLE -POLE NORMALLY OPEN SWITCHES.'S CONTACT S P N C 10 AMP @ 120 VAC STANDARD JUMBO DIFFUSED FLASHER LED S JL PI KEY ASSEMBLY VOLT OPERATION RED JUMBO SIZE o frr. the Musical Ringer story has errors in the Yes it is! In fact.. somewhere (nowhere that we know of now).00 EACH 606 S.000 mId. I think someone is toying with you because there is a toy on the market called the Solar Piano (S11 -106) that is available from H & R Corporation. (on -on) p I80 S.ra11116 y_Bi34T. 15 VDC 13/4-DIA -4-HIGH WALL TRANSFORMER $2. VERMONT P. EXCEPT EACH SWITCH OPERATE INDEPENDENTLY $2.T.T. - 5 STATION NON. CA 00006 FOREIGN ORDERS INCLUDE SUFFICIENT SHIPPING CALIF RES ADO S I B' CIRCLE 426 ON FREE INFORMATION CARD Two 8's and 9's You blew it! In the Fall 1984 issue.00 $1. FL 386 audio chip and loudspeaker.P.M EACH FOR Sen FOR S' 13.75 $3. because once I do I will be proven wrong. regulated voltage. Detroit.00 SUB -MINIATURE D TYPE CONNECTOR EDGE CONNECTORS }i IIRi::Q:6I::. we since everyone who purchased the chip received a pinout diagram with it. all the unused inputs (gates) on that chip can be connected together and connected to a hi through (Continued on page 21) .D.00 EACH RED 10 FOR 51.50 EACH SOLDERING IRON STAND COMPUTER GRADE CAPACITORS SPRING STEEL IRON HOLDER 2. has two sets of 8 and 9 pinouts. Is that correct? regulator IC's. A pre -programmed microchip is used to generate two switch.000 mfd. 2 AMP CONSTANT. Memphis.B.09 EACH 10 FOR $9 00 100 FOR l AMPS @ 125 VAC S.F4 2F 28/56 28/56 GOLD PLATED CONTACTS 156 CONTACT SPACING . Yes. It is a novelty item which demonstrates the use of solar energy. etc. First off.13000 13 VDC RELAY L.50 4VDC _á70 MA 9 VAC @I AMP 12 5 VAC @ CLAMPS TO FIT CAPACITORS Sol 5200 S3 00 265 MA VAC @ 500 MA 24 VAC @ 250 MA 17 $2. 4 AMP SURGE UL LISTED $13. 40 VDC 13/8 33/4" HIGH DIA 4 ON WEIGHTED BASE $5.600 m1d.. ALL FEATURE 100% SOLID STATE CONSTRUCTION. almost everyone figured out the goof.00 EACH 10 FOR $18 00 DB -15 DB -15 DB -15 DB -25 DB -25 1". was too low. You are quite mysterious about what the output would be too low in a noisy the project is that requires such "clean" room or den where the hi -fi was blasting.50 $1. The 6 -volts DC is cutting it close.. Yep. I've made two now and have an order for one more (my mother -in -law).00 3.ÿ4L. So. Well. DOS 20408 ROCOCO' I D. etc. As for the two S13's.P. you have two S13's. 15 VDC 43'8 -HIGH 2" DIA SJ 50 155.E..400 mfd. MI I I LE(TRO5fl CORP ELE(TR0f1ICS CORM? QUANTITIES LIMITED MINIMUM ORDER 91000 USA 1300 SNIPPING I I $1.50 $2.SWITCHES 5 STATION INTERLOCKING 2PDT AND 2 6PDT SWITCHES ON FULLY INTERLOCKING ASSEMBLY 3'. BETWEEN MOUNTING CENTERS $2.50 ALL ARE 11S VAC PLUG IN 72. 6 VDC 41'2' HIGH 21 /2'OIA $1.. However. schematic diagram.T. etc. FUSE PROTECTION. 401 East Erie Avenue. Also. THREADED BUSHING SI . 200 VDC 13/4-DIA 5-HIGH 52.00 6.P. there is an electric car (circa 1909 or there about) that recharges its battery from sunlight.D. MEASURES 3 3/4" LONG EACH 2 LJLJ ENERGIZE COIL TO OPEN CONTACT COIL 13 VDC 650 OHMS SPECIAL PRICE $1. Raise the Voltage am running a 7805 to provide +5volts of regulated DC to a project that is a bit fussy about power requirements. G.P.u5' -nn PLUG SOCKET HOOD PLUG SOCKET H/lll $2.25 jl MULTI.00 YELLOW 10 FOR $2.50 31. J.00 EACH Y4" HIGH $2.00 LOS AMOEI-E6. Chip U1.selected tunes-Nocturne and Minuet.8 VOLT REGULATED POWER SUPPLY THESE ARE SOLID STATE FULLY REGULATED 13 8 VDC POWER SUPPLIES.O. Please set the record straight in your letter column. (on -on) I PC STYLE NON -THREADED BUSHING 7S4 EACH 10 FOR 57 00 F 5 SOLDER LUG TERMINALS $1. L E 0 POWER INDICATOR //// '.O GIGS UMBER SWITCHES INES complained that the audio amp output runs well in the house. I'm inputting the regulating circuit with a 6volt lead -acid cell that has the oomph to power 100 such projects and still the regulation is a bit "noisy.G. chip with more zonk! The details of such The input voltage to the 7805 should be an amplifier will be found in this issue. I'm using a multi -input AND gate and Try 8 -volts DC. the Musical Ringer is a great project. about three volts greater than the output voltage to provide good regulation by the Close the Gate chip.D. 2'V @ 1. torque CCW rotation.ryo ?Al. Voltage: 12/24/110VDC & 115VAC. . (RECHARGEABLE) APPLE 2c DISC DRIVE $139. electronic equipment. hook -up diagram.115V.25A OUTPUT: Pin 1 Pin 2 Pin 3 Pin 4 +5 VDC. +5V @ 3A. . Dim. video games. Input 115V. 2 C 24 SPEED CONTROL FAN "x3 "Wx3 %"H.05A. blowers. compatible with Apple 2e. 50/60 Hz. CIRCLE 428 ON FREE INFORMATION CARD In New Jersey. Dim. 13.I.:3'.MOTORS -POTENTIOMETERS.95 NEW SERIES FIELD MOTOR Replace the membrane keyboard on your Timex Sinclair Z-81/1000 with this brand new "big computer" keyboard from Texas Instruments.: Potter Blumfield or equiv. $4. Charge oonly.J. Base mtg.95 NEW NEW PLUG -IN POWER SUPPLY INPUT: 120 VAC /60 Hz. Sales Tax (N. 60 Hz. $29. 50/60 Hz.95 NEW AMERICAN DESIGN COMPONENTS.3A ground Mfr. 201.. hand tools to variable speed. .95 NEW $6. . blowers.: 7'4" x 6'. $3. Ideal for portable fans. Canadian: 3rD s P.. O 19" COLOR 35 CFM D - Mfr. 120V.: Rotron Model SU2E1 Centaur #CNDC24K4 601 $14. or visit our retail showroom and find exactly what you need from the thousands of items on display. Contacts. B 115 CFM MUFFIN We Metal frame with 5 high impact plastic blades. Exp. 4 PDT 3 -5 amps. residents only. Contains 10 AA cells. x 1. Lets you use your TV set as a monitor for video and audio signals produced by home 110VDC-115VAC. 240 VAC full load. $5. Master Card Visa YES! Plese send me the following items: Total NEW S -2 21 VAC @ 2A TI Model tac 9610 NEW MINIMUM ORDER $15..O. TOLL-FREE 800 -524 -0809. Mounts for intake or exhaust.O.J.65 AH Contains 11 C Cells. Portable computer battery back -up Mfr. intake or exhaust. GE e41B035BB00101 -18 hrs. . AMERICAN DESIGN COMPONENTS? A warehouse 60. Ideal for cooling electrical /electronic equipment. Has electromagnetic deflection and solid state circuitry with three "Z" amp inputs Ired.939 -2710.645" deep Mfr.50 "Wx'.: Arrow Hart #51824 $9. Voltage: 24VDC- Originally designed for use in Atari coin operated games. "D 12V NICAD BATTERY BACK -UPS With our full 90 -day warranty.1x 13/4 " Mfr.95 My check or money order is enclosed. KAP /KRP Type.:2"Hx1Y: $3. focus and brightness controls.. .95 x deep. Wire leads.24VAC. Ideal for arcade replacement or. Contacts: double break. 30 A. B. or removed from equipment (RFE) in excellent condition.. But quantities are limited. Date Signature Telephone: Area Code Total 01 Use wherever you have to vary the output voltage. converts fans. FP . TRANSFORMER INCLUDED! $4.COMPRESSORS -BLOWERS. For cooling Hi Fi. Dim.939 -2710.75 NEW 6 AMP VARIAC VARIABLE OUTPUT TRANSFORMER RFE How Many? A. Continuous duty.95 NEW PUMPS. Contains a 19VLUP22 3-gun color tube.P. C.04A. HO-55 Card No. 1.exepensive. Open Mon.-1. etc. - $129. OUTPUT: 12V @ . Mounts for intake or exhaust.00 P -2 RFE computers. RFE KEYBOARD TM55-4 DS/Quad RFE 15.VOLTAGE REGULATORS-POWER SUPPLIES AUDIO & VIDEO R 4 -POLE CONTACTOR S 115 VAC WALL X -Y DISPLAY Q MODULATOR ADAPTERS P -1 KHP Type. + VDC MUFFIN FAN 115 CFM. 96 T.95 RFE RFE COMPUTER DISC DRIVE SWITCHING POWER SUPPLY F E H qt44. se' dt N Shipping & handling. Contacts: TPDT 5 amps. 12V @ 450 Ma. Description Price $2.95 M12 schematic included. 115 VAC. Terminals: screw or quick connect.1A 12 VDC. + 5V @ . Mfr. with the adds Lion of external circuitry. 11 Watt Metal frame with 5 high impact plastic blades. Charge my credit card. Dim.95 + 24V NEW Coil VDC 115/120 VAC. Variable output 0. Manual included.: 3. Dim. etc. N./. electronic & computer equipment.. INPUT: 18 . Mfr.95 0 -100% adjustable.7 amp Ino load) Speed: 3400 RPM.5V @ . etc. 07074 $3. 5 -pin din cord..mechanical components for the hobbyist.6A.95 48 KEY 53/4" TANDON DISC DRIVE /: Ht.50 RFE SPRITE FAN - Low noise level. " x 1 Si "D.. Mfr. 115V. Power supply regulator board for microcomputers and games. and 2C. 50/60 Hz Contacts 4 -pole N. facing shaft. otherwise specified.95 NEW Input: 12 VDC @ .14" sq. etc.COUNTERS TIMERS -RELAYS. please add 6% of total) ORDER TOTAL For all phone orders. -Sat.What's New at "The Source" of the electro. surveillance cameras. 9 -5. Order from this ad. computers. call Number Name Address City Zip State All inquiries and free catalog requests call 201. often hard -to -find components for sale at a fraction of their original cost! You'll find every part you need either brand new. For cooling Hi Fi. GE #123233 or equiv. blue).95 RFE K Original equipment drive.: Coleco Model 55416 + $6. Recharge rate 45 MA. $ $19. Teccor MSC 218 THERE'S NO RISK. for color graphics display. @ 2. $7..00 INPUT: 115/230VAC. $5. DC OUTPUT: +12V @ .5A. any purchase can be returned for any reason for full credit or refund. 16 Dim: 2'. 2300 RPM @ 25 in.00 T Made for Texas Instruments. - $7. 2% " 9 VDC @ 100 ma Model #6040 S -1 $1.17A. Complete with 8'. we ship UPS unless total.9A -5 VDC. On/off switch. MOONACHIE. Simple to install complete instructions and $99. green.: 4'Y. Case with tab output connections. 60 Hz.000 items at American Design Components. 62 JOSEPH STREET.: 3" dia.95 NEW t t . Dim..gcost. Panel mount. /lb.2A. 6 amp. 1111 733 330 *ID 2 10 211 C.n.11111. OrsYr TO Was 01 CM111 17.5. EwM._ 0.9 .m.s LDER TAIL DIP SOCKETS S ì 10 MAI COO.107 0111000. ..4711.0 .00 -s 9. 0101 1 - .. VOLUME DISCOUNT s 0._.con ONO 910 0 40 NAN SON eá EDOESOARD CONNECTORS .o... - - N.ra tr 0 IN CAT NO 54791.0103 b 40M 11001. 77 91 7M 1 III ID 11 OM II 0 4133 CI IS 30 0/0 IN 60s Max I 37 .710 I: 40464 Yt..40rr 10011 14000 N. WA oñ er 41 0 61 0 12 Ney i SO 3 73 370 421 1110 07 31 75 6 400 47 00 0 400 333 CO 10 00 uo610. NN.s._n 7.OS... 1 402.47740 775103Y/ le Nm EDGEBOARD CONNECTORS 11.R Nw 1tl SO C431 0 W s 9 11Ni 149 1 V 01 S s 0.43...MO1Y. IN 11120 3 07 21.. .Volume Discounts OEM Quantity Pricing Toll Free 800 Number CHEMICALS MICALS ARIES S OPLCHEMICALS IV 001 RI.W. YOeeeeme Lem N s 1 N 47 01 119 u 6. Ow SO 23 CO 1r 7 LaPL.N1 e. 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CNEMICALS ARIES EMWIK tN MACHINE DIAMOND TOOL UNGAR VISA AAVID SERVICE .tors S11. 0ro1Ir DISC CAPACITORS 0.Y4.001 EIr 0101 - a. % 40170 507/1007 LAWN. J 1117 1000 RAS 4000 74 °1a 401 ] aNw 9.1..N aaCW.. NPO TYPE NISI.1 3 07 OP 40/ 60 646 .0051... 041 ..rd Ma. 0r 010rí1-.704 .n. waw. rai ANN non non 30.7 O. 2 10 401065 375 40110.1 Saw. 17r 0.r.00 Add ICES AddN.o° nm 001.. 01 05.1NA M sa...aN 11 016 0 o 1 7 10 30 ON 7010 19 1 MA...01 NIr DO/ NIr I PLESSEV ATLAONTIC DIODES... o.2 Ona16AC1 3 19 7774 1% 31 LIAMIIM 40710 I IN. n..202' 166.tiOM Pew... ..11171D 7011141i5 CA71CI1pR5 ] MIS Om 70..4sr SI r. mpLen w refund CIRCLE 417 ON FREE INFORMATION CARD 1 016 03 777 73 WS 1.0 0504. 701 710 4110. rem 74000 130 MO 7017111116 3 71.140s1s0YAYf1 -NA SO 01311119 r.COnNe..a/. 14010 ..Oc00 . 11111.n.E.. w. 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Moo .. n.. s n m .°°°.99 500..u1 Gloss Zene1 Diodes - 11176YM0 70 110 46 14 441 077 i 'á :s w mYYe'n - UP A1112/1.G... 14 872. fir 1.f..veto.mn n TOW 011000 44 7...B P . MOM lw. 674474.0 w.60 -.3 7511 a 3I..140. 1.0 ó 70 101617.7 NO .6011. 4 ww :-i.m410616 ..24 NO 77 54 ' ST7rT.4.. ... MN co 31 SG 24 6103 246 CO Staks MIt...16110 NAUSS * 30111 701 aw 1017 211 : ..s. IN OD 31 A. . .7 71. 11.6 w a'..99 10008 Up ' CIRCLE 417 ON FREE INFORMATION CARD .4. 1. °1..60 30 0 21 71 1771.10 .01 n 7.M" 11d mnrm:e. Wow U S A 100 3444939 MK. _431... lid DO. 1s0 .rn Mo c4s eE 010. 710 ñé 510 460170 416 NO .... - 14124-7640 :70 11. .NNECTORS 1 6774 WO 41:5 16 447 1710 3910 71.vw. 01..13717..76:2C..$999.w. /161 1134 CO 3Aa .41.a..w. CON n 444.ö P R O C A R O al I T - 1 . 3127 .4 äM 113 ID 33 N.aa.O.1100 103 04114. `°wr1 or \ . aMal M.Iu .10.enwe S AYYa Soffit TYM Knm F..1111110 111 1.rs 0. T A..3510 711 110411 niii-om 34 44 MIS CIS o 1W 117 1.0.2.0 317 001 5 SM. WOOS H.e rwwa 407 OD W .4 0117 NW 211 7111 INN 7111 ..14 0 01 NO 1.s oa . 440. 2 44 21 301 22 14 In i. 1.L.. Ì°°O 010040 110160 10 O 10 6wN SW NO 111 1 1.rr 040..0. rr r o r/n O®. .51 441142 ..AI 01.nM.. 0670 W.eMS.610..11.r 9a.007 07 NCO 0..140417 .r 0.310...5110 731 7014 140 . n: m BB88..:111t . IN w1 POW* . Maw 00 s1. 100.á s AO Oa 772 ñ»NO a 1.4074 mm co ''7047 111..0 411VH10. 7661..e. r... :Aslr. ..0 3330.nm. wION WO' 3277 3700 A 031 413100. 4.. o 1. 7 On. ..". 7 12 M ..w.. RIO. 1011 IS IN .1 7 700 4361 mac r -.7) 7771 m 600.75 $0. IIC l'..aw4N 7. eua .6011.M .40 .. 17 m1 . 1p l WNW.5 m .M.: ZO 1 141.+. to 400 PIV.. 244 X . 1137 1.0..640 MOSS 2. . 22 1Á0s10 MO NM NW so. opto. call collect: (216) 354 -2101. etch.. plus the analogue switch. five -way. Hackensack. colorful Heathkit Catalog.000 DIFFERENT ITEMS IN STOCK! Sale. NJ 07602. detailed operation. 5 families of thyristors. and examples of key specification parameters.I.95 each (plus $1 postage) from Micro Logic.en. TERMS COD vow IPSTI Me. CIRCLE 451 ON FREE INFORMATION CARD MANUFACTURERS OF QUALITY ELECTRONIC COMPONENTS BATTERY CLIPS CABLE SETS B MOLDERS CONNECTORS CAPACITORS LED. Or. including the new Hero Jr. pre. Box 174. and shift command. the Ace 118 saves the user valuable time in circuit building and troubleshooting. voltage regulator. Fenton. ACTIVE REFERENCE CHART If you design or repair electronic circuits for fun or profit.. Coming fully assembled. and more. Complementing that variety of configurations are a picture frame and center line design of 544 distribution tie points. Available in 2 sizes with 1 or 2 sided foil. attached to the base plate.ChR (Open . CA 92071 (619) 449-2222 TWX 910-331 -1175 CIRCLE 424 ON FREE INFORMATION CARD The buses can be linked to offer such functions as voltage and ground distribution. P. comparator.ability" and stays stationary when circuits are being built on it. Schmitt trigger. Circuit creativity is made possible by the Ace I I8's 1280 -terminal tie points. These copperclads use the latest technology of negative acting dryfilm photoresist. Other KeproClad products such as a photo reversal kit for making negative film. 4 types of light emitters. tone decoder. or other external equipment. a marking pen. Highlighting ACE 118 are its four standard. makers of quality industrial equipment and supplies.343 -1630 Toll Free 800 -325 -3878 D BUILT A BETTER BREADBOARD A P Products has added ACE 118 to its 100 series of All Circuit Evaluators. call or write: KEPRO CIRCUIT SYSTEMS. home robot. KeproClad was designed for the home user who needs professional results with: A Simple Circuit Board.O. Use KeproClad unsensitized copper clads.d 00. ACE 118 accepts all DIP sizes as well as a wide variety of discreet components. Micro Chart No.95. R 00. multiplier.. A Fine Line Detailed Board. light . Dept H04. In Ohio. VCO. by Kepro.by Keprn CRCUd Systems Inc At Home Professional Quality Fine Line PCB's. These boards come in 2 popular sizes with 1 sided foil. Telephone: 201/342 -6518.d USA Send S? 00 MOUSER ELECTRONICS 11433 PHONE 8 WOODSIDE AVE SANTEE. Use KeproClad photosensitized copperclads.. NEW HEATH CATALOG Over 400 electronic products in kit form. Micro Chart No.by 11 -inch plastic card that is packed with information. From Micro Logic. This new solderless breadboard is economical. and you will end up with circuits that are simpler and less expensive to build. reset line. PLL. Typical descriptions cover: names of part. 9 types of light receivers. Up to 18 14 -pin DIP's or 16 16 -pin DIP's can be used in this universal matrix of 1824 solderless plug -in tie points. This material is rugged. preformed. signal names. 10 and other timesaving cards are available for $5.measured Jumper Wires from A P PRODUCTS can be used. one shot. all for a suggested retail price as low as $3.. the board has "heft. yet holds extremely fine detail.. signal generators. you can now get a CIRCLE 452 ON FREE INFORMATION CARD handy plastic reference card that lets you get right to the basic workings of active electronics components. carrying a suggested retail price of $39. yet contains features that are unique for its size. are showcased in the latest. or advanced terminology.hI1 Phone end Mad Welcome ado. In addition.90 (suggested retail).coupler. 6 types of transistors.. For more information or the name of the nearest A P Products stocking distributor call toll free: 800 -321 -9668. is fully programmed with speech output. bridge rectifier. step by step method for the home production of professional quality printed circuit boards without a major equipment investment. voltage follower. fabrication methods. If you repair circuits. (For the distributor nearest you.KeproClad. varistor. op-amp. (coolest M. MO 63026 -2992 In MO 314.e. you will not have to stop and research unfamiliar parts. 630 Axminister Drive. CIRCLE 411 ON FREE INFORMATION CARD r ELECTRONIC COMPONENTS. Circuit elements are easily interconnected with ordinary #22 AWG solid wire.l ONn I. It comes with a premeasured amount of developer and sells for as little as $3. Refer to this card while designing circuits. tin plating solution and photoflood lamps are all available at your local distributor. INC. clock line.50. and Order D. Hero Jr. 10 entitled "Active Electronic Components" is a two -sided two -color 8 -1/2. FUSES TACKS & PLUGS DISPLAYS KNOBS LAMPS POTENTIOMETERS RI COILS RELAYS RESISTORS SWITCHES SEMICONDUCTORS SPEAKERS TEST EOUIPMENT TRANSFORMERS TOOLS WIRE A CABLE OVER 15. binding posts. . A/D and D/A. Those make convenient connections to power supplies. sample and hold. The chart covers everything from op -amps to programmable unijunction transistors without having to go through theory. Non -digital functions readily available in a single monolithic package are covered including 13 diode types. Since the back plate area is of steel. inexpensive. Introducing an easy. . Granby. Consult the telephone directory white pages for the nearest store.2% 108 VAC to 135 VAC.W. Benton Harbor. current limiting. recites nursery rhymes. CT 06026 CIRCLE 454 ON FREE INFORMATION CARD 1 YEAR 203/651 -0285 MHz. 890 -6107. Ripple less than 10mV at full load. the PowrPure unit gives effective protection against short-duration. and can act as a security device and wake up alarm. Line Regulation <0. E.350 -inch OD cable. Warranty: one year full replacement warranty from date of purchase.5 amp max. Each marker is perforated.. supply or a neg. NOT A KIT! LOW PRICE!! 1 51.. Thus.they can also be stacked in series so that a 5V and two 15V supplies can total a 35 VDC supply or any combination of the three. H04. plays games.adapter..0 amp max. The Hotshot Dialer features an easy. with thermal shutdown. VISA. Variable supplies 0.S. DISTRIBUTOR AND REPRESENTATIVE INQUIRIES INVITED IN 0 i_ iMN E. MI 49022.and sound sensors. Ontario M8Z 5Z3. The 3 perforation arrangement is CIRCLE 421 ON FREE INFORMATION CARD 9 ... and Canada.135 VAC. write Heath Company. Those are just two of the over 400 electronic products offered in the new Heat hkit Catalog. In Canada. Regulation 51% no load to full load. It plugs into any standard modular phone jack or Y. or neg. To receive this colorful catalog free of charge write Heath Company. Fully adjustable from 11 VDC to 35 VDC! Three completely independent supplies that offer many advantages! They can be either a pos. for the first time you can now purchase this American made fully adjustable power supply at a price that is onehalf of what you'd expect to pay! 1 SPECIFICATIONS outputs. The first part is a teminal marker and the two remaining pieces will mark both ends of an attached wire. an ultrasonic sonar. consult "Electronics Parts Wholesalers" in the telephone directory yellow pages or call toll -free 800/225 -8326: in Mass. Dept.floating. 9 ozs. Free catalogs are also available at Heathkit Electronic Centers and Heath/Zenith Computers and Electronics Centers in the U.(after one of the terminals is grounded to give it a reference). SURGE -PROOF YOUR OUTLET The EMF -315 PowrPure voltage surge and noise suppressor provides an inexpensive means of protecting costly electronic equipment from both transient voltage surges and RF noise interference. supply. ENGINEERING. It permits the use of an alternate long distance service without lengthy 13digit phone and billing numbers. To locate the nearest distributor. MODEL PS101 FULLY ASSEMBLED & TESTED! 88 S - FULL 1 REPLACEMENT WARRANTY Made In The United States - Protection built in. t0 ISV TO :S. 108. Toronto. The EMF -315 clamps voltages to a safe level below 500 volts without interfering with normal current flow. can be used as pos. He sings songs. WIRE MARKER DOES THREE JOBS An unusual wire marker lets you do three marking tasks without letting go of the applicator tab. Fixed 5 VDC 0. AMEX TELEPHONE ORDERS ACCEPTED! 6 Herman Drive. The new GT -2218 Hotshot Dialer is a unique one -number telephone dialer that quickly dials any telephone number up to 31 digits. easy-to-read Voltmeter and large binding posts. and attenuates RF noise up to 40 db from 200 kHz to 30 NAM SEIECI POwEM This DC triple regulated variable power supply has all the features you could ask for plus a full year guarantee. Power.. INC. and an onboard computer system. 3 t Current: Fixed supply 1..to -pro- gram memory that doesn't require battery backup since it is manually programmed. Lighted on /of power switch. The com- plete marker will fully encompass a 0. 1020 Islington Avenue. high -voltage spikes and prevents faulty equipment operation caused by RF noise on AC power lines. Dept.2V 2 variable $1'/: V to 215 VDC Polarity . Further information can be obtained from authorized distributors of Philips ECG products. MASTERCARD. Dimensions: 8Y:" x 31' x 7Y:' (WxHxD) Wood grain finished metal case. drive and steering motors. H04. by simply picking up the phone. and also allows an emergency number to be dialed CIRCLE 453 ON FREE INFORMATION CARD A QUALITY TRIPLE -REGULATED POWER SUPPLY AT A LOW. Weight: 4 lbs. MULTI -CHANNEL NEW PRODUCTS DUAL unique; each perforation line has a different strength so that the marker will always tear apart right at the wire or terminal. The balance is either used immediately or is replaced on the card for later jobs. The marker's adhesive is impervious to most oils and hydraulic fluids. POLARITY MICROWAVE TV SYSTEMS Complete Systems From 569.95 Full 800 MHz Range Antenna Tunes 1.9 to 2.7 GHz Includes All ITFS Channels 428 449 428 429 9 i 4 1 1 4Zft 4 `x30 L.? 429 DEILLFRS WANTED .18 SILVER STAR COD's and Credit Card Orders Call TOLL FREE CIRCLE 455 ON FREE INFORMATION CARD GALAXY MICRO STAR Adhesion to vinyl insulation is initially moderate to enable repositioning; bonding increases substantially after 4 to 6 hours in place. Flexy- Markers are available in bound sets of 24 31/4- x 51/2-inch cards. Marker styles include letters, letter -number combinations, twelve NEMA -EIA colors, and single and consecutive numbers from I to 520. Marker quantities vary from 624 to over 1000 per set, depending on individual marker width. Price for any set is $6.95 Electronics 5644 N. 53rd Avenue firti Glendale, AZ 85301 1-602- 2471151 VISA 1 CIRCLE 423 ON FREE INFORMATION CARD uQeQ-a4 50NGoo a as %.00G P` . e\ For more info, write to The Datak Corporation, 65 71st Street, Guttenberg, NJ 07093. Telephone: 201/869 -2200. S .13 Not M ode Sum\e FOAM -FILLED COMPUTER CASE Jensen Tools introduces a new zipperstyle case filled with high -density poly foam for conveniently and safely trans- 4 ModSapy òe 5 °I 1. OA p dees °1 S NOOS cotm0 p\aVSette \pe Pec.° ty each etc ta\ °t a o\e o a personal computer and peripherals, or other sensitive electronics equipment. The two-inch layer of remova- m ode\ peGe deQeec\oe0e9eta\te oG \eae cot\uot.j \ev red te etc ..00s,,,,,, °` es co e P :sat- E ma\ ato a\\s AaNp Ypoe eac0ed State co0QCe5eecpedes taP Ph°e at\d é0ee)g e; \ ca\\ ! i s\o \éePt`0 e sleets 450 \e\ted S1 4wa0vFdt WY, rS c ,6)\I v+h stoPs cpedeess¢he CIRCLE 456 ON FREE INFORMATION CARD 5` oo* ee r 4P4 0\ e em°tme a G e 0e1"°". ShP e Mór,e r d` . Ma : . ` Aea `Pg33ÿ ,pcó O,nS\NCoe,3 E. 9 9g ) P,`. a o 8 e 6a5k9 e e2 CIRCLE 422 ON FREE INFORMATION CARD 10 EIfW;d1V7R. wM10DpIIWeE RIA, NW -... . »,.1 ,.o ...n ..t porting 4 hoeée\te to sd Unprotected transfers easily wear off if repeatedly handled. General purpose aerosol sprays aren't much help; they contain aggressive solvents that cause a dry transfer to dissolve, wrinkle, or even float out of position before repeat coats can build a protective film. ea. S95.000'. heeate GLUE -DOWN RUB -DOWN TRANSFERS Once a curiosity, rub -down transfers (dry transfers) are now part of the project builder's tool kit. The letters stick to all surfaces, but permanence is a problem: 1- 800-2471151 Mod documentation. The largest pocket (10x 14- x 21/2- inch) will accommodate an operating manual. Two smaller pockets (10- x 7- x 21/2-inch each) provide ample room for a tape recorder, modem, power cords, lunch, etc. For more information, or fora free catalog about other special kits and cases for computers, write to Jensen Tools, Dept. H04, 7815 S. 46th Street, Phoenix, AZ 85040. Telephone: 602/968 -6231. ble foam can be cut to match the exact shape of practically any personal computer. A foam pad affixed to the inside of lid offers additional protection. Measuring 16- x 11- x 31/4-inch inside and covered with rugged cordura nylon, the case also features three roomy outside pockets for additional accessories and/or CIRCLE 457 ON FREE INFORMATION CARD Datakoat acrylic spray has been available. It is excellent for overcoating transfers on metal, plastics, and paint, but it will not form a smooth film on porous materials like paper and tracing vellum. The Datakoat rests on top of the transfer, but sinks into the surrounding surface. The porous- surface problem has now been solved with Hardkoat, a unique spray for rubdown transfers on paper and porous surfaces. A single coat softens and penetrates the transfer ink, then glues it to the surface. Abrasion resistance is superb. Additional coats are not needed unless severe weathering is expected. Hardkoat is supplied in 12 -ounce spray cans in either a gloss (Cat. #04170) or matt (Cat. #04171) formulation. Price for either is $4.75 each. For more information, write to The Datak Corporation, 65 pure, solderable tin over copper, brass, and non -alloy stells. No acid is added, and there is almost no odor. Plating is done at 110 to 130° F. The metal should be reasonably clean. but cleaners in Tinnit prepare the metal for a perfect plate. A maximum plating thickness of 0.0004 inch is reached after 15 minutes in a fresh 71st Street, Guttenberg, NJ 07093. Tele- phone: 201/869 -2200. TIN PLATE Electroless tin plating has usually meant a dull gray-plate with marginal solderability, poor adhesion, and a fourmonth solution shelf-life. Most formulas also require the addition of a strong acid. Datak solves those problems with Tin nit, a dry, chemical mix that can be stored for years without deterioration. When mixed in water it plates a shiny layer of i CIRCLE 458 ON FREE INFORMATION CARD VIEW 8 TRACES ON YOUR SINGLE OR DUAL TRACE SCOPE WITH THIS LOW COST DEVICE!! 1 -4 5 -8 1 8 IIIIIM E W EWG/ifA.G /,C M MIN AX AMPLITUDE MIN MAX SPACING POWER NI CHANNEL SELECT OUTPUT LO INPUT SAMPLE RATE Now you no longer have to spend thousands on an expensive multi trace oscilloscope - our single trace Hitachi scope combined with this module will allow you to view up to 8 simultaneously occuring analog or digital (or both) signals in their real time and amplitude relationship. The MPX 101 may be used on any oscilloscope, whether single, dual Or multiple traces. Its low cost makes it a particular favorite for designers, testers, hobbyists and repairmen who want to compare and analyze displayed signals in a timing diagram format. The controls on the front panel of the metal case allow you to vary amplitude and spacing of the displayed signals. MODEL MPX101 FULLY ASSEMBLED & TESTED! solution. Tinnit was designed to plate bare-copper circuit boards, but it can also be used for general cosmetic plating. Although tin's resistivity is slightly higher than gold, Tinnit works successfully as a protective plate on edge -card connector fingers when gold is not available. Tinnit (Catalog No. ER-18) is supplied in a 600- square -inch (I -pint) size for $3.50. Large bulk quantities are available on an individual quote basis. For more information write to The Datak Corporation, 65 71st Street, Guttenberg, NJ 07093. Telephone: 201- 869 -2200. DIGITAL TV The Toshiba America's CZ -2094 is a digital -TV model that boggles the mind with a variety of features and functions. The set will have a suggested retail price of $1,199. The model has full compatibility for the audio -video range from home computers to the approaching direct- broadcast satellite. teletex, and videotex systems. The set uses Toshiba's FST (flattest, squarest tube) with fine -pitch shadow mask for higher resolution. The quality of the picture is exceptionally high. due to the processing of ordinary TV signals dig- itally. 88 FULL 1 YEAR REPLACE- NOT A KIT SPECIFICATIONS Inputs: 8 signals plus ground via 9 input leads terminated with alliga- tor clips Bandwidth: ± 1dB to 5 MHz Impedance: 10.9 K Input Voltage: ± 5V peak (diode clamped to ± 5 Volt supplies) Output: Staircase waveform summed with input signals, 0-800 mV full scale Step Amplitude: Variable 0 to 150 mV/ step Signal Voltage: Variable 0 to MENT WARRANTY - Made In The United States - 150 mV/step @ 5V Input Multiplex Rate: Switch selectable, 40 KHz or 4 KHz Impedance: 50 Ohms Power: 105 -135 VAC @ 1 V a Dimensions: 6.25" x 3.25" x 4.75" (WxHxD) Operating Temperature: 0-40 °C Weight: 1 lb. 10.5 oz. Warranty: one year full replacement warranty from date of purchase Lighted on /off power switch Wood grain finished metal case DISTRIBUTOR AND REPRESENTATIVE INQUIRIES INVITED ii E. W ENGINEERING, INC. VISA, MASTERCARD, AMEX TELEPHONE ORDERS ACCEPTED! 6 Herman Drive, E. Granby, CT 06026 CIRCLE 420 ON FREE INFORMATION CARD 203/651 -0285 The CZ -2094 has a digitized chassis that converts analog signals and processes chrominance, video, and deflection. digitally. By using its digital circuitry, the set has picture- within -a picture capability when used with a second signal source. The viewer can freeze the inset picture by using the set's memory storage, or can enlarge the inset picture from I /16th to I /4th of the total screen size. Other features include 138- channel cable compatible, both 8 -pin and 21 pin (Continued on page 12) Electronic Systems Newsletter The magazine written especially tor the electronics hobbyist /experimenter Fascinating Projects New Ideas Tips & Techniques Sources New Products Each issue brings you exciting and unique articles and projects including information on Designing with Leds Control Systems Backlighted Visual Displays Electronics Directory Components & Circuitry Book Reviews Trouble- Shooting Tips Business Opportunities Construction Features Communcations Robotics Lasers ... and much more. NEW PRODUCTS (Continued from page 11) RGB inputs, three audio/video, input/ output terminals, stereo-bilingual sound receiving capability, on- screen -control and function indicators, multi- function wireless remote -control, and a new 2 -way, speaker system. Sold at major television retail outlets. THE RUNNING PROGRAM MECA (Micro Education Corporation of America) has found a way for runners to use their personal computers to help improve their running and overall fitness through a guide for all levels of ability. The Running Program, MECA's innovative new software, provides every runMIKA JANES F. RA( FREE DETAILS i cf AF PUBLISHING CO. Dept M P O Box 524 So Hadley. Mass 01075 ning, who helped develop the program for MECA. The Running Program is available for the IBM PC, XT, AT PCjr and COMPAQ. The suggested retail price is $79.95. Available at most computer software outlets. LOW -COST POCKET-SIZE MULTIMETER Non - Linear Systems new AP-l05 Digital Multimeter is so small that it will fit inside your pocket! The AP-105 is a low cost, 31/2-digit multimeter that can be used just about anywhere that electrical measurement is needed. Besides AC and DC voltage measurement, the AP-105 incorporates seven additonal functions including: DC current, conductance, resistance, NPN and PNP transistor, diode, and battery test. A single, convenient, rotary switch selects on -off power. function, and 23 different ranges. The AP-105 measures 4.8- long x 2.8wide x 0.9 -inch high, and it weighs only seven ounces. It also uses a large 0.5 -inch LCD readout with high- contrast numhers- automatic polarity and overload in- CIRCLE 412 ON FREE INFORMATION CARD ït A forest fire can take your breath away. NIk 01, /'t 7.61 A Public Service of This Magazine & The Advertising Council 12 CIRCLE 459 ON FREE INFORMATION CARD ning enthusiast, from the occasional jogger to the serious marathon competitor, with a personal running coach to help them set individualized goals for general fitness, weight loss, a "10K" race or a marathon. It's all contained in one easy-to -use package. The Running Program begins by evaluating current fitness with six simple tests. With that information, the program develops realistic personalized day -byday training schedules. The Running Program prints the runner's schedule and summaries of training, racing, and nutritional records. It then goes on to keep records and graph achievement statistics for the entire family -including records for swimming, cycling, and 30 other types of exercise. In addition, The Running Program tracks and evaluates the runner's diet for weight control and shows the runner (through innovative graphics) six stretching exercises that will help to minimize the chance of injuries. The Running Program will ultimately predict the runner's probable race times and best competitive distance. The Running Program is dedicated to James F. Fixx, the founder of modern run- CIRCLE 460 ON FREE INFORMATION CARD dication are included. The multimeter is powered by a 9-volt transistor -radio battery with a life of 300 hours. A low-power indicator is also provided. NLS products and information are available at local electronics distributors throughout the USA. CONTINUITY TESTER Vaco recently introduced the new No. 70305 Continuity Tester, a handy tool which instantly detects shorts or broken circuits in all types of electrical devices. Used for testing circuits with power off, the 70305 is ideal for checking lamp cords and fuses, motors, electrical appliances, switches and receptacles, and many other devices. It features an 36 -inch lead wire (Continued on page 20) All books returnable within 10 days - without obligation Club News Bulletins..S.95 1604 List 524. "".-r . Box 10.Saving Advice .1i: .95 List 515. may return the books within ten days without obligation and have my membership cancelled.95 List $14. Foreign applications will receive ordering instructions.95 List $16.50 (paper) List S17. Blue Ridge Summit.95 List $19. currency.. Immediately get a Dividend Certificate with every book purchased and qualify for big discounts of 60% to 80% Exceptional Quality.ELETUIIJE The Best INTEGRATED ELLJE THEORY Source for Hobbyists and Professionals for Over 19 Years! .. All books are first -rate publisher's editions selected by our Editorial Board and filled with useful up-to..95 plus shipping and handling charges...95 List 519. Canada must remit in U.95 (paper) 1820 List $16.d Lmr_. ppO)[LT... V 9EN(t11' (11M1710L k 1fTUN tl1ti11 TFI'NVOI f E.and Money. 1616 List 619.l'n 1672 1218 1665 List 518 95 List 518. Exceptional Savings . my FREE utility apron..O. Do nothing and the Main selection will be shipped automatically! But if you want an Alternate selection -or no books at all -we'll follow the instructions you give on the reply form provided with every News Bulletin Bonus Books.95 very good reasons to join the Electronics Book Club 1650 1577 List 519..95 imam 8 1818181 ELECTMINC 6181ní MIN Mi16T6 1605 1932 1690 List 519. PA 17214 Please accept my membership in the Electronics Book Club and send the 4 volumes circled below. Save 20% to 75% on books sure to increase your electronics know -how No-Risk Guarantee.95 List $21. Get Utility Apron FREE! a 1539 1670 1599 List 521 95 List 514 95 List 521. I I 1108 1183 1211 1218 1393 1431 1492 1539 1542 1577 1583 1593 1599 1604 1605 1616 1650 1665 1670 1672 1690 1699 1740 1765 1777 1820 1875 1932 Name _ _ Phone Address City State lip r---------------.the-minute information .95 List 519.95 FREE Utility Apron 7 Big Savings.95 List 517.95 Digital 1492 1211 List $14. Practical Troubleshooting & Repair Tips . agree to purchase 4 or more books at reduced Club prices (plus shipping/handling) during the next 12 months.:n.the-minute titles to pick from Automatic Order. ELECT110NaE00hE LUE P. .95 .95 Take Any 4 Books for Only$295 Join Now. extras -plus bonus offers.95 Wuww wnan-. and may resign any time thereafter. 1593 1542 1699 List 513. All about current selections mains. billing me $2.95 List $15.95 List 621. Time.95 IC BASIC TRANSISTOR COURSE Set. If not satisfied..95 List $21. . alternates. This order subject to acceptance by the Electronics Book Club RESP-585 ..-Mil Valid for new members only..95 (paper) I 1740 ist 518. State -of-the -art Technology Hundreds of Projects Plus. 1875 1583 1393 1431 1108 1183 1765 1777 List 521 95 List 519.n..95 List 512. plus. Comes 13 times a year with hundreds of up -to. here is a comprehensive look at the evolution of cryptology by America's foremost writer on the subject.O. and author of the bestselling The Codebreakers.95.5 amps . Foreign Affairs.50 ea.D in Modern History from Oxford. 14 CIRCLE 427 ON FREE INFORMATION CARD individuals. Prepaid orders sent freight C. EVELYN AVE. Hardcover. beginning with the invention of the abacus five thousand years (Turn to page 16) .000 quality items. 10/$9. Soviet spy ciphers. detect the increased Soviet activity on Grenada? Could the attack on the marines stationed in Beirut have been avoided if communications intelligence had penetrated the situation? Those confrontations have sparked CARD CIRCLE 425 ON FREE INFORMATION CARD z SPECIAL DEALS Dble. and the search for an unbreakable code are some of the subjects covered in this collection of articles written over the past two decades. and coeditor of Cryptologia the age CIRCLE 490 ON FREE INFORMATION CARD flurry of questions about of our intelligence operations and a magazine. and wth more computers under one roof than any Jensen's new catalog is jam -packed with more than 2. scientists. Today. engineers. 22 . 827 E.25 ea. Some items limited to stock on hand.FREE! New Catalog of Hard -To -Find DON'T Precision Tools v D FORGET D J Kahn on Codes -Secrets of the New Cryptology By David Kahn Why didn't the National Security Agency..50 94c ea. rather. $ . makes plain the complexity of modern -day surveillance (and its impact on the private citizen) in his latest book. AZ 85040 (602) 968-6241 SERVICE other U.50 ea. New York. Prepaid orders over $100.25 ea. orders.156 Edge Connector Solder Tail Dble. the importance of cryptology to our national security. MT. KANN ON ODES mans or Trie IVEW CRYPTOtOGY $1.95 10/$1.. SUNNYVALE. 343 pages.00. California residents add 61/2% sales tax. 16 Pin Solder Socket (machined pin) 16 Pin Tin Wire Wrap Socket (2 level) 20 Pin Tin Wire Wrap Socket (2 level) 22 Pin Tin Wire Wrap Socket (2 level) 24 Pin Tin Wire Wrap Socket (2 level) 1 amp Plug In Xformer 4164 150 ns $ . $ . VISA MASTERCARD 10 for $7. and The New York Times. E NSEN TOOLS INC. use money order or certified check. no longer limit their intercepts to official communications. the effectiveness MacMillan Publishing Company. Please do not send cash. $ . and they touch the lives of every one of us. 866 Third Avenue. USE YOUR READER 7815 S.D. historian. This popular catalog also contains Jensen's world-famous line of more than 40 tool kits. they draw intelligence from the communications of private firms and David Kahn.00 $ .00 $ . as well as the layperson concerned with government intelligence and his own liberties. or call for charges. INC. CA. For the codebreaking buff. with an annual budget of $I billion. 8 VAC 51/4" diskettes. there are millions. shipping will be added to credit card and C.39 9 for $25. 100 for $35.00 10!$1. instrument mechanics. and the war historian.25 ea. 94086 WE SHIP C. 240 VAC 1. 19. David Kahn. Like most other revolutionary inventions.D. noted cryptologist. Your single source for hard -to -find precision tools used by electronic technicians. Game / TV Switchbox ASTEC VM1291 -1 Video Modulator postwar growth in intelligence technology has affected individual rights.50 AMERICAN EXPRESS HALTED SPECIALTIES co.O. has been an amateur cryptologist since of thirteen. 10 . NY 10022. Institution. 10 Sector Flourescent 10 Digit Display 16VDC Flourescent 12 Digit Display 16VDC Solid State Relay PC.156 Edge Connector PC. comes with schematic 10 for $12. Governments. according to Kahn. Call or write for your free copy today! t J.D.00 box of 10 $9.65 ea.00..O. there wasn't a single computer in the world. Kahn ranges from the allied codebreaking successes of World War II to how the Bit by Bit -an Illustrated History of Computers By Stan Augarten Just forty years ago. No refunds -exchange or store credit given within 10 days. 10/$5. 46th Street Phoenix. schools. a Ph. MT.00 Used with most Video Games Switch Selectable for CH 3 or 4 RCA output. 408 -732 -1573 TERMS: Minimum Order $10. Tapping computers. He is an editor of the Long Island daily Newsday. Many of the articles in collection were originally published in periodicals as diverse as Playboy.35 ea.00 1.88 ea 10 $15. the computer was the culmination of a long chain of technological developments. $1. laboratories and government agencies.S.40 ea. 8k Up to 50 WVDC 220 270 330 470 O hms 10k 15k 22k 27k 33k 47k 88k 271 -1311 271 -1312 2.6 25.49 .2 1. and more! Learn basic electronics by building your own circuits from Radio Shack parts.99 499 1.2 3.99 2.99 . No. No. Books. 12 VDC coil. Connectors. 3 49 276 -4008 Over 1000 items in stock: Binding pos s. No. 276 -1801 276 -1802 276 -1822 276-1805 276 -1808 1/4 -Watt.44 .89 .79 . Features easy -to-read text and large diagrams.69 . Breadboards.Change Digital precision at a great low price! Fea- Pkg. No.99 4.69 .95 "Barrel" Diodes.047 pF .59 1.49 1.000 devices to their low-cost Radio Shack equivalents.89 . test leads and manual. Capacitors. Resistors.59 . Zener Diodes.19 1.29 6. Clips. Each Type PIV 6.6 CT 450 mA 25. 275 -225 Getting Started in Electronics Semiconductor Reference Guide 1995 Only 249 Only 349 Learn As You Indicator tures convenient .0 2. LS and CMOS digital circuits.59 .2 CT 450 mA 1.Center CT Volts Current Cat. No Reg.7k 6.69 . 271-1301 10 100 150 Operational Amplifiers Type 5 5% Resistors Cat.59 .2 to 37 VDC Type 7805 271 -1341 271-1342 271 -1345 7812 7815 271 -1354 271 -1356 271 -1365 Cat.79 89 . Multitesters.19 1.79 .99 5.59 Electrolytic Capacitors Forr Printed Type 2N1305 MPS2222A PN2484 MPS3904 TIP31 TIP3055 MPS2907 MJE34 2N3053 MPS3638 TIP120 2N3055 MJ2955 2N4401 MPSA42 2N3819 MPF102 IRF511 IRFD1Z3 2SC1308 Circuit Boards Cat.44 . 500 volts AC. Batteries extra 22 -191 59.89 Pkg.1350 271-1337 271 -1339 271-1340 pushbutton zero-adjust and a diode/ semiconductor test mode. It's ideal for controlling high -power lighting and auto accessories. No. Colorcoded LEDs and hi /lo tone indicate high.99 1.95 By 200 Forrest Mims III Pages Cross over 80.44 .89 LM339 (Quad) TLC271 (Single) TLC272 (Dual) TLC274 (Quad) 276-1712 276-1748 276 -1749 276 -1750 1.99 79 Heavy -Duty Design With Mounting Bracket SPST contacts are rated 30 amps at 12 VDC. Chokes.99 5.59 2.29 1.59 1. Really useful! 22 -302 19.79 Voltage Regulators Replacement Transistors Handy "Beep" Continuity and Range.99 1N4001 1N4003 1N4004 1N4005 50 200 400 600 12. Relays.19 TTL Digital 1 c Type 4013 4017 4049 4066 Power Supply Diodes Micromini -Amp Diodes. PC Boards.99 6.99 Each 1.44 Z5U Z5U Z5U Z5U 272 -155 272 -156 272 -157 272 -158 . of 2 1N5400 1N5402 1N5404 50 200 400 276 -1141 276 -1143 276 -1144 . 741 (Single) Each MC1458 (Dual) LM324 (Quad) TL082 (Dual) 276-007 276-038 276-1711 276-1715 .59 1. Jacks. No. Famous for Value! The Store for Builder's Since 1921 Power Transformers 4000. SCRs.49 3.69 .99 1.49 1.1347 271.29 1.Series CMOS ICs Primaries 120 VAC With Pin -Out and Specs ' ' ' Type Cat. No. + 5 VDC 276-1770 + 12 VDC 276-1771 + 15 VDC 276 -1772 . Each . Fuses.2 300 mA 273-1386 273 -1365 273-1366 273 -1351 273 -1352 273 -1353 273-1511 273 -1512 273 -1515 2.19 2. Plugs.69 . No.69 . of 2 50 WVDC 44% Off Temperature Coefficient 10 pF 100 pF 271-1313 271-1314 271 -1315 271 -1317 3. Rectifiers.44 . Cat.0 2.29 1. 128 pages. Each 276-1740 276-1778 2.3k 4. Hardware.2 12.0 CT CT CT CT 1. Transistors.99 pF Cat.99 1.3 300 mA 273 -1384 12. Includes detailed data on Archer' ICs. 30 -Amp surge.59 1.99 2.1 pF 21 -Range LCD Digital 5995 MEN Multitester 1k 271 -1321 1130k 1.44 . LEDs diodes and more. No PNP 276-2007 NPN 276-2009 NPN 276-2010 NPN 276-2016 NPN 276-2017 NPN 276-2020 PNP 276-2023 PNP 276-2027 NPN 276-2030 PNP 276-2032 NPN 276-2068 NPN 276-2041 PNP 276-2043 NPN 276-2058 NPN _2762061 N-FET 276-2035 N-FET 276-2062 V-FET 276-2072 V-FET 276-2073 NPN 276-2055 Digital Logic Probe Each 1.6 300 mA 273 -1385 25.69 . Buzzers.6k 271 -1324 271 -1325 271 -1328 271 -1330 271 -1333 220k 470k meg 10 meg 1 Cat. 200 -Amp surge.69 . of . Measures up to 1000 volts DC. Wire. AC and DC current to 200 mil liamps. With spare fuse.2 A 6.ftadie Ihaek Parti Plaee®_.01 pF .79 3. SALE NPO NPO NPO .6 25. Switches. No 271 -1335 271. low or pulsed logic states. ICs. Transformers. and for switching Ham radio power 4 99 supplies.19 .99 3.49 .2 18. 276 -1101 276-1102 276 -1103 276 -1104 Build! Over Simultaneous Tone Output Frees Eyes for Fast Testing Lets you "peek inside" TTL. and resistance to 20 megohms in 6 ranges.99 Adjustable Type LM723 0 to 40 VDC LM317T 1.79 Fixed Output Cat.99 . Each 4001 4011 276-2401 276-2411 276-2413 276-2417 276 -2449 276-2466 . Type PIV Cat.44 Z5U 272 -151 272 -152 272 -153 272 -154 . 2 49 276 -5003 Radie lhaelt A DIVISION OF TANDY CORPORATION Prices apply at panccipatnq Radio Shack stores and dealers CIRCLE 414 ON FREE INFORMATION CARD . Miniature Miniature Miniature Miniature Miniature Standard Standard Standard Heavy -Duty Heavy -Duty Heavy -Duty ICs . No. No. Each 470 1000 2200 272 -1046 272 -1047 272 -1048 1.3 12. Overload and polarity protected.69 .2k Monolithic Ceramic Capacitors on Sale Epoxy Dipped 39.99 Value Cat.59 2.59 3. Knobs.19 . Pkg. Tools.49 30 -Amp Automotive Lighting Relay 1.09 Ohms Cat.0 A A A A A 3 -Amp Tap With Pin -Out and Specs Type 7400 7404 7408 7447 7490 Cat.69 .79 1.59 1.49 795 3. Lamps.44 470 pF 1000 pF 4700 pF . to Stephen Wozniak. STAN T AL/GAMIN CIRCLE 491 ON FREE INFORMATION CARD University.A. it is also about the brilliant. * - 5V /DIV.fledged computer.(REQUIRED 25%DOWN) DELTAX CIRCLE 419 ON FREE INFORMATION CARD DELTA Ex DYNAIC INC. forward looking. AUTOMATIC RECHARGE BRIEF SPECIFICATIONS: DEFLECTION FACTOR BRIEF SPECIFICATIONS: DEFLECTION FACTOR 2MV to 10V /DIV.century genius whose Analytical Engine came within a inch of being a full. With magnificent photos culled from around the - BITBY E An Illustrated History u. TIME BASE: 0. $17. He has been a reporter for the Associated Press. CALIF. graphic techniques. (5X gain) RISE TIME: Less than Ions. BUILT -IN BATTERY.50 for shipping handling and insurance. Blacksburg Continuing Educational Series. TIME BASE 0 to 0. TRIGGER FOR TWO -- NON.2µs to 0. Paperback. 324 pages. IMV /DIV. DELAYED TRIGGERING SWEEP. Cr' I1 jci 1 SINGLE SWEEP. to today's superfast computers.5 s. California residents add 6' : °i sales tax. TELEX: 503749 DELTAX . Paperback. He has an M. Howard Electronic Prototype Construction By Stephen D. DELAYED TRIGGER SWEEP FEATURE AS DX5035. NY 10017. and often eccentric men and women who have shaped the computer's history-from Wilhelm Schickard. TIME BASE: 0.DIV 5MV to 20V /DIV. i_v__A/s 74* #4 0. the debonair 19. Stan Augarten is the author of State of the Art A Photographic History of the Integrated Circuit. Orders shipped UPS add 58.95 (714) 594 -7131 TO ORDER: CALL COLLECT MONEY ORDER. SWEEP STARTS AT TIME DELAYED. the author tells the whole computer story for the first time-from grooves in the dirt. 0.. in American history from Columbia BOOKSHELF (Continued from page 14) ago.95. - 10V/DIV. W. IN 46268. Inc. look into Electronic Prototype Construction. Satisfaction guaranteed. Ticknor & Fields. the obscure German professor who invented the first mechanical calculator in 1623. you are an active project builder.1µs 0. DX5015S 15MHz $510.O. and a news writer and producer for television stations in Oakland and San Francisco. VISA. (Continued On page 30) DELTAX DUAL TRACE OSCILLOSCOPES (TWO QUALITY 10 -1 HOOK ON PROBES INCLUDED) SALIENT FEATURES: BUILT -IN COMPONENT TESTER. FILTER SALIENT FEATURES: PORTABLE. WIDTH. C.5 DX5020 20MHz $379.. . IMV /DIV. New York. Kasten While many books are being written in the wide open field of electronics concerning the design of microcomputer and computer interfacing circuits. TV VIDEO SYNC. BRIEF SPECIFICATIONS: DEFLECTION FACTOR: BRIEF SPECIFICATIONS: DEFLECTION FACTOR: 5MV /DIV. 399-pages. SCALE ILLUMINATION. Now.2µs - DX5045 45MHz S789. very little practical information is available about construction techniques for converting schematics and ideas into functional electronic prototype units. SMV /DIV. and a superbly written text. AUTOMATIC TRIGGERING. ALT.world.A.00 TERMS: One year limited warranty on parts and labor. Indianapolis. Bit by Bit is both a guided tour of the world of the computer and an absorbing account of its evolution. DELAY TIME BECOMES DIM. This book was written to fill that gap. or return unit in original form for 16 DELAY LINE TO PERMIT ANALYSIS OF RISE TIMES. $17. But the book is much more than a story about machines.SYNCHRONIZED SIGNALS. RISE TIME TIME BASE: s 5p /DIV.95. Penfold Information on standard circuit building blocks is available from manufacturers' catalogues. 91789. It can be divided into the following four major features: Wirewrapping. and beads on a frame. WORK ON AC DC. MASTERCARD. printed-circuit boards. RISE TIME Less then 23m. Sams and How to Design Electric Projects By R. 4300 West 62nd Street. and hardware packaging.5 s /DIV.00 SALIENT FEATURES: SALIENT FEATURES: -afsZAA.5 s /DIV - AI" DX5035 35MHz $527. 52 Vanderbilt Avenue. to Charles Babbage. WIDE FREQUENCY BAND refund within 10 days from date merchandise received. If CIRCLE 492 ON FREE INFORMATION CARD Co. (5X gain) RISE TIME: Less than 8ns. A Houghton Mifflin Company.95 1W- I Less than 17ns. WALNUT.D. the young electronics wizard who founded Silicon Valley's Apple Computer Company. 000 worth of software. Data Communications. you grasp the "secrets" that qualify you for a new career. Let others worry about computers taking their jobs. And you can start by actually building NRI's 16 -bit IBM -compatible computer. If some other ambitious person beat you to the card. You'll use utility programs to check out the operation of the Sanyo's 8088 microprocessor (the same chip used in the IBM PC). you'll learn at home on your own time. including WordStar and CalcStar. ArA FSCHOOLS McGraw -Hill Continuing Education Center 3939 Wisconsin Avenue. high paying future as an NRI trained computer service technician. troubleshoot and service computers. You'll learn to program in BASIC and machine language. write to NRI at the address below. you can succeed with NRI training. NW Washington. in the comfort and convenience of your own home. Send for Free NRI Catalog Send the post -paid reply card today for NRI's 100 -page catalog. There is still plenty of room for you to get in on you get the proper the action -if training now. You'll start with the basics. you'll build a Sanyo MBC. You're always backed up by the NRI staff and your instructor. no rigid night school schedules. DC 20016 -' We'll Give You Tomorrow. That means your preparation for a new career or part-time job doesn't have to interfere with your current job.. rapidly building on the fundamentals of electronics until you master advanced concepts like digital logic. And you also get over $1.With NRl training at home. You'll learn at your own pace. . you can. Learn at home in spare time With NRI training. peripherals. only from NRI To learn how to work on computers. As part of your training. that you keep. and software. with all the facts about computer training plus career training in Robotics. No classroom pressures. 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G. /low lo chose the one that hest Is your needs. by Robert Grossblatt HOBBY CORNER by -Doc Savage.. connect to a hi only those inputs that you want hi. The C -130 "Hercules". This will be coming to you when you subscribe to Radio -Electronics HELPFUL CONSTRUCTION To Equipment Accessories Telephone Accessories Music Synthesuers Computer Equipment Automotive Eguip.SOLID... hum. and both are in wide use in the U.. It was a natural.Ne Kew Idea Equpmc+ll Arno. SATELLITE TV STEREO How o..center system Makes PLUS Drawn. connect the unused gates to used gates..S1.utomated test." in the near future. FUTURE. It could handle large currents and was very rugged.c State.. On. armed forces and the Coast Guard. please forgive us should we not answer your letter is impossible to answer all of them. nor Speech Syntheseei. When you select one of the subscription offers listed on the handy coupon -you'll be assured of having your copy reserved. and is in wide use in its military and civil (Lockheed L-100) versions around the world. The cures he claimed were more psychlogical than real.nle it y. the shaft rotated. Better still. The hot -wire ammeter was just another link in the antenna system that was sensitive to current changes at any frequency. The hot wire is an averaging device and added almost no loss in the antenna` line. You don't see too many meters of that type today. Longer Life once read that human life can be extended by placing ourselves in a magnetic field. NEW AUDIO DIMENSIONS FOR YOUR PLEASURE. it heated up and stretched. Park. Both..on TV 5atellne TV Receivers Jeck Darr Monthly Semce Cbmc Semce Problems and RECHARGEABLE BATTERIES. Maplewood. What s .. in fact. Hot Wire How accurate were those old hot -wire ammeters? M. by filling in and mailing your subscripton card today. and not camouflaged.yad.. game reviews and NEW IDEAS. body are produced R.. You don't need a resistor to do that. -it 21 . Thanks for the extra details. That string was wrapped around a shaft at its midpoint. dup1a11C s. It's been so good to know you.SnW._OMPUTER PRODUCTS FOR HOMEJOB and MUCH MORE Radio -Electronics covers all aspects of the fast moving electronics field. it's hokum! Friedrich (Franz) Anton Mesmer promoted magnetism as an effective medicine. Now. That goes for all chips. The armed HOW YOU AND THE COMPUTER CAN BE FRIENDS. Later. and since it was wrapped around the shaft.P. Intruder Alarms.featuring VIDEO STEREO COMPUTERS TECHNOLOGY SERVICE COMMUNICATIONS PROJECTS Get it all! Subscribe today to Radio -Electronics! Don't miss a single issue and. Wrong Plane On page 91 of the Winter. Summerville. Make sure you get all the excitement in every issue of Radio -Electronics. It is. Thermocouples do a better job with RF and jeweled meters are rugged enough today for automotive and portable use.. new products.LETTERS smaller (half the size) turboprop transport... Essential information is used to guide the editors in preparing the next issue.Es add -on for you sateóle TV renewer lunes you onto stereo arda. new products. K4505 STATE-OF.. MA . in the old days hams wanted to measure the output of their antennas. 1985 issue.. Each letter is read carefully.. STEREO PRODUCTS. So. COO. by contrast. don't look I for doctor's prescriptions reading.STATE by Bob Scott WHAT S NEWS. ss is Satellite TN Teletext Automotive Eli. NEWS ON NEW TECHNOLOGY Computers MicroPro.. incidently.S. The string moved a small amount. Trig Peripheral Equipment SPECIAL BUYELSGEON Electronics ELECTRONICS BUILD THIS IN MEDICINE. The spring felt the slack and pulled on the string as it took up the slack. SC is a (Continued from page 4) the same 1K resistor. a C -141 B "Starlifter" heavy jet transport. Rad Fo Getting Started Programs Cr ua Design Games ADDS Interta. Servie CY. The smaller C -130 is also used by all of the other U. Detroit used meters of that type in automobiles to indicate charging current.oersted permanent magnet.. forces should color-code aircraft rudder surfaces like resistors so that we novices may read the model numbers. Latest Receivers and Circuits The Home Entenainment Solutans SATELLITE TV COMPONENT BUYERS GIP -'. IC Applications FASCINATING "HOW TO DO IT" ARTICLES. However.. as current went through the wire. you crin quickly cd out your Many Noise -Reduction Deices HOW to Connect that Extra Add -On He Fi Accessories New Technology Center Pmlect. With Bits . Can you give me more facts? P. Put a pointer on the shaft and you have a hot -wire ammeter Why the need for a hot -wire ammeter? Well. There is some interaction between magnetic fields and life forms.l..e.rd Hobby TV WONDERS FOR YOUR REGULAR MONTHLY FEATURES DESIGNERS NOTEBOOK BUILD A COMPUTERIZED IC TESTER. even if it sells out on the newsstand.s.. Of course.. We enjoy receiving letters from our readers..000. NJ Oh. Build Your Own You Own PC Boards Wmng Techniques Soldering and Desoldenng Deogn and Pratotypirg Thanks! If the plane were all shiny aluminum. the aircraft pictured is not a C -130. to pone ingeth. every month. However. Air Force. stereo news VIDEOGAMES...O1.tgesot the human DEMODULATOR.100. Home & Car Video Accessories Mt -F... "1 -. the Solar Maximum observatory (or Solar Max. Solar Max carried seven scientific instruments that all are simultaneously used to monitor a flare.FOR ALMOST AS LONG AS THERE'S BEEN ELECTRONIC equipment to break down. 1980. straight up. Trouble in Space During its first nine months in space. The Solar Max On February 14. three fuses in the satellite's Attitude Control System blew. but none will top the one that can be told by Drs. and how that energy effects the earth. In fact they are so complex that no single instrument can monitor all of their features. how they release their energy. suddenly. and from X -rays to gamma rays. George D. the Solar Max mission was a smashing success. Because of that. Nelson and James D. One such year of peak or solar maximum activity was 1980. Its mission was to provide solar scientists with information about the sun that was impossible to obtain using earthbound instruments. and solar flares in particular. That rendered all but three of the instruments . causing the satellite to lose its ability to point its onboard instruments accurately. Radio amateurs are familiar with the effects caused by those massive solar storms. from visible light to ultra -violet. Now most service technicians probably have their own tales about a way our service call. there have also been service technicians to come out and fix the wayward equipment. their service call took them nearly 270 miles. After all. Solar flares are complex phenomenon. Then. The seventh instrument on board the satellite is used to measure the total radiation released by the Sun. One of the things known about solar flares is that they appear to occur in cycles. as it is commonly known) was launched. earth -bound communications can be severely curtailed and brilliant auroras (northern lights) may be generated. Within hours after the occurrence of a flare. the Solar Max was launched in that year to learn more about the Sun in general. The data gathered by those instruments is used to help us learn more about how flares start. van Hoften. thus. with peaks in activity falling about 22 every 11 years. during the active period. Among the subjects to be studied by using the satellite were solar flares. Six of those instruments are used to measure the energy emitted in the electromagnetic spectrum. at least in part. Later. It consists of three cradles. a fifth instrument developed an electronic problem and failed. The support system was designed to mate with the multimission modular base of the satellite. Those modules. and the repair of a satellite in space is no exception. but the instrument was positioned in such a way that it was felt that a repair was feasible. and more difficult repair was the replacement of the main electronics "box" in the Coronagraph/ Polarimeter. That repair was to consist of two parts.shaped and fills the 15 -foot width of the of the shuttle's cargo bay. and relative importance to earthbound solar scientists. and A prime. For any repair job the proper tools are needed. A Service Call The space shuttle Challenger. Because of its design. It's the first in -space satellite service call! useless. Solar Max was chosen to be the first test of that ca1 pability. One part was the replacement of the Attitude Control System. called A. One of the most important tools used in the repair is the Flight Support Sys lem. But until it was actually accomplished.By Carl Laron SPACE T S CHNICIANS :RVIC TH SATELLITES High above the clouds and atmosphere astronauts serviced Solar Marc. Nevertheless. The faulty Attitude Control System was one of three replaceable modules. one of its primary benefits was intended to be the repair or retrival of satellites. the Solar Max project was declared a success. with a crew of five. and are designed to be used in a wide variety of satellites. and a circular ring to . The Flight Support System is U. since the lifetime of the satellite was reduced from an expected two years to just nine months. or corona. 2). Because the mission objectives established before the launch were met. 1984. which are used for such things as power and positioning. an instrument that was used to study the sun's outer atmosphere. on the next page). designed to be repaired in space. a great deal of useful data was lost to earthbound scientists. But Solar Max was one of the first of a new breed of satellites: one that was. are located in the bottom portion of the satellite (see Fig. by creating an artificial eclipse. They are are standardized units. a mounting platform for the satellite during repairs (see Fig. was launched from the Kennedy Space Center in Florida on April 6. When the space shuttle program was first conceived. no one could say for sure that such a feat was possible. B. called the multimission modular system. That instrument was not intended for repair in space. Among its prime mission objectives was the repair of the Solar Max. and the faulty circuitry was located inside the insulated shell of the satellite. The second. attachment device. A special tool (immediately above) is used by George Nelson to disassemble the module.i Solar Maximum Mission Satellite (SMMS) orbits through space. Astronaut George Nelson (upper right) space walked to connect the trunion pin. 24 Jr ' /' 4 . (upper left) providing no useful function due to the on-board malfunction. Astronauts James van Hoften (right) and George Nelson (left) work cautiously on the faulty attitude -control module in the Challenger's open cargo bay. In the photo at right. Transition Adaptor Module Support Structure Trunnion Pin Grapple Point Power Module C and DH Modules High -Gain Antenna System (HGAS) weigh 500 pounds. To complete the repair. which has been specially designed for that task. 9. and an electric screwdriver. One of those units. 1. On earth they would Berthing Berthing Ring Umbilical Connector Latch as the 2- During repairs. One of the problems of repair in space is that while objects are weightless. measuring some 4 X 4 X 1. To secure the satellite. The three modular units at the base of the satellite are intended for replacement while in space. Power and heat from the shuttle are provided to the satellite via umbilical connectors. the Attitude Control System (ACS) was replaced in space by Drs. If one of the modules were set in motion by accident. That kept the satellite's solar panels constantly pointed toward the sun. 14. even though it is weightless. three berthing latches clamp onto pins near its bottom. adhesive tape. 3. Instruments 5. it would be hard to control and could do considerable damage. And that service call was no exception. and the protective insulation reattached. That's because. a panel is unscrewed and opened. The Flight Support System provides electrical and mechanical connections between the shuttle and the satellite under repair. 11. the satellite is mounted in the Flight Support System cradle.7 feet. On earth.Fig. Instrument Support Plate Solar Array System Attitude Control System (ACS) Module 8. the astronaut must first cut through the foil insulation and remove the screws that secure a protective thermal blanket over the instrument. The latches are used to hold the tool in place. But the "tool kit" used in its repair might be a bit more familiar to earthbound technicians. When the satellite failed. exposing the main electronics "box ". (If a regular socket wrench were used on those bolts. Fig. the faulty box is disconnected and removed. 7. That module service tool. which the satellite can be anchored during the repair. After taping the insulation and blanket out of the way. the satellite retains its momentum. is controlled by two handles and two switches. the new module is retrieved and mounted using the tool. keeping the unit's batteries fully charged. socket wrench at the end of the device is used to loosen the two retention bolts that hold the module to the satellite. A rotator on the support system can turn the satellite. rarely do things go as planned. Best Laid Plans As any one who has ever serviced electronic equipment knows. Because of that. the astronaut would turn-but the bolts would not move!) Once the bolts are removed. they are not massless. the astronauts doing the repair must work carefully and slowly. \ Cradle A Cradle A Prime Cradle B 25 . which is about the size of a briefcase.shaped cradle fills the the width of the shuttle's 15 -foot cargo bay. That U. To remove the faulty module. 6. 13. The faulty module is then stowed in a temporary location. two latches on the tool are inserted in matching holes in the module. the service tool is used to hold the module and it is slipped off the satellite. It consisted of scissors. is used to remove the modular Attitude Control System. the panel closed. the new one installed and reconnected. Electronic Enclosure 4. the module will be examined to find the cause of the failure and may possibly be repaired for future use. Thermal Enclosure 3. and a pivotor is used to tilt the satellite at any angle from upright to horizontal. stable spin of about one degree per second. A module service tool. The Coronagraph/Polarimeter unit is not a module. As you might imagine. grabbing a spinning satellite is no simple matter. Coarse Sun Sensors 2. James D. and its repair is more difficult and time -consuming. see Fig. Nelson. ground controllers placed it in a slow. The modules are large units. To do the repair. and the faulty module moved to its permanent location for return to earth. 1 -An exploded view of the Solar Max satellite. 12. van Hoften and George D. 10. A Nice Catch The fourth day of the mission was used to attend to other activities not related to the repair of Solar Max. Dr. or MMU (see Fig. using telemetry. Nelson tried to steady the satellite by grabbing onto one of its solar panels. the satellite's batteries would power the satellite for only an additional six hours. and mission support for the STS -3 and STS -4 space shuttle flights. it was decided try using the manipulator arm once again. This time. Van Hoften and Nelson could get at the electronics more easily. this time moving in a bit faster.3 -The module service tool serves as a zero -torque socket wrench and as a handle -grip to move the defective and new modules about. Because the satellite was turning much more slowly (at about half of its original rate). but still could not dock. That.7 pound thrusters. an astronaut -in this case Nelson -was to fly over to the satellite using a jet-powered Manned Maneuvering Unit. they were able to stabilize it to the point where the satellite was holding almost perfectly still. early on the fifth day. then. and because fuel levels aboard the shuttle were beginning to run low. Though originally scheduled for two days. When he reached the satellite. called the Trunion Pin Acquisition Device. He is a specialist in shuttle guidance. And. instead of spinning in an orderly manner. The module weighs about 500 pounds on Earth. the shuttle successfully grabbed the satellite and hauled it safely into the cargo bay. By the mission's third day. Crippen carefully positioned the shuttle under the satellite so that astronaut Terry J. But damage had been done. So far. because of the problems the crew ran into while catching the satellite. development of the shuttle -era space suit. the second was that the solar panels were no longer aimed toward the Sun. the Challenger had caught up with the wayward satellite. (Continued on page 98) MEET THE SPACE TECHNICANS Dr. TPAD. Fortunately. By the next morning. To accomplish the docking. Nelson was to stop the spin by docking himself to a pin protruding from the Solar Max and using the maneuvering unit's 1. they caught it on the first try! The satellite was then brought into the cargo bay and secured to the Flight System Support cradle. After Nelson returned to the Challenger. all repairs now needed to be completed in one day. To perform the maneuver. George D. and astronaut Nelson set out for his short 10. As a final attempt. Nelson (right) is an astronomer with experience in astronomical research. ground controllers were able to stabilize the spin. Nelson returned to the shuttle. the satellite's orbit swung around and pointed those panels toward the sun just before time ran out on Solar Max's batteries. In fact. more fortunately still. and flight control. Hart could extend the manipulator arm upward and grab onto the satellite's pin. the jaws within the TPAD failed to clamp onto the satellite's pin as they were supposed to. navigation. mission commander Robert L. the docking attempts had begun to disrupt the satellite's orderly spin.minute trip to Solar Max on schedule. 26 . he matched its spin by firing the MMU thrusters. By now. Fig. Once at the satellite. All of those attempts also failed. Then trouble hit. was to stop that spin so that the shuttle's manipulator arm could pick up the satellite safely. the satellite was spinning unpredictably about all three axis. 4). only made matters worse. The failed docking attempts caused two problems. The fifth day of the mission was the day that repairs were performed. van Hoften (left) is a hydraulic engineer and leader of the Astronaut Support Team responsible for Space Shuttle testing and flight preparations. four attempts were made to grab the satellite's pin using the shuttle's manipulator arm. When he attempted the docking. To do that. the satellite's batteries had almost completely recharged. and it was time to try to retrieve the satellite once more. Now. Since the MMU's fuel supply was now running low. James D. and the satellite was pivoted around so that Drs. though the panels were still pointed away from the Sun. But. Because of the latter. a special receptacle. The first task. however. was mounted on the arms of the MMU. so good. The first was the uncontrolled spin. Power was supplied to the satellite through the umbilical connectors. Nelson tried again. 44114 1776 East 17th Street ' I Cleveland.800 -362 -2155 (in Ohio.000 students. From the basics to CIE's Associate in Applied Science Degree in Electronics. 1.I. Robotics. And with plenty of hands on. Ohio Please send me your CIE Off -Campus Studies Catalog.800 -362 -2105) or mail in the handy reply coupon below or card to Cleveland Institute of Electronics. 1776 East 17th Street. The hottest careers in electronics. Cable television. including details about the Associate Degree program. With over 50 years of proven experience teaching electronics without classroom sessions. Cleveland Institute of Electronics. Ohio 44114. Why CIE? Because we're the leader in specialized electronics education with over 25. but there is no obligation. Just call tollf ree 1. take you as far as you want.What can you do with electronics? Ask CIE. practical experience using our specialized training laboratories. Cellular radio. CI E World Headquarters Inc. Digital electronics. understand there is no cost for the catalog and a CIE representative may call. Satellite communications. 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The aim of this book is to do just that. by helping the project builder put together home brew gadgets fmm circuit building blocks with the minimum of trial and error. Hints on designing circuit blocks to meet the experimenter's own special requirements. where no stock designs are available, are also included. The subject is tackled by taking a series of simple practical examples. analyzing exactly what each circuit must do. exploring possible methods of achieving each circuit action. and then working out practical designs including component values. Thus a number of useful circuits are provided as well as project design advice. Electronic Technology Today, Inc., P.O. Box 240. M /S -1-10E4. Massapequa, NY I1762 -0240. Softcover, 101- pages. $5.75 plus 5.75 for postage and handling. THE CET EXAM BOOK By Dick Glass and Ron Crow Whether you're just starting out in the electronics service field or you're an experienced technician who has just never gotten around to getting your CET certification, this is the ideal sourcebook to prepare you for that exam. It is not a guarantee. but you may pass it the first time with flying colors! Thoroughly practical and completely up -to-date, this guidebook will set aside any fears you might have had that the Certification Exam is based strictly on theory, rather than the everyday workbench knowledge you rely on in ET 'CIE EXAM BOOK ER CIRCLE 493 ON FREE INFORMATION CARD your job. It shows that what you need is a realistic balance of hands -on know how and basic theory. And, with the confidence you'll gain using this book's sample questions and explanations, there's no reason why taking your exam won't be as simple as doing your everyday job. 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Everything -is applications data and projects that provide you with hands -on experience. To provide you with the background you'll need to apply IC's to specific projects, there are complete specifications for representative IC's, including analog devices this technology. An and both simple and understanding of what data CIRCLE 494 advanced 7400 devices. communications is and ON FREE INFORMATION CARD Applications information what it does may be as further aids your synchronous interfaces, future as necessary in the understanding of this modems and digital knowing how to dial a Circuit Integrated Basic versatile electronics optic fiber transmission, It is something telephone. Theory and Projects technology. You'll get a and satallite you need to know. By Charles K. 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No advanced applications illustrated Instruments form a library cover such topics as: An include flip -flops, a counter math or science background written for anyone who overview of data is needed, because the module, and a comparator. wants to learn easily and communications, data IC With this background, down has broken author today's about more quickly terminals, messages and you'll be able to theory into easily digestible electronic technology and transmission channels, segments, complete with immediately put your IC the era of personal asynchronous modems and knowledge to work using a series of 24 exciting and useful projects. Build a "In Just A Few Days, I'll Show You How To Do NAND gates. series NAND gates. and wired AND gate. a NOR gate or series NOR gates. On Your Calculator!" b ' from facts and figures for computing, its impact on our world, and its application in our lives. Each book is written in bright, clear, down -to -earth language and focuses on one aspect of what's new in today's electronics. Texas Instruments, P.O. Box 225012, MS -54, Dallas, TX 75265. Paperback, 272 pages, $14.95. Understanding Data Corrtrrxntcations corporations, telephone network control signals, banking and credit -card purchases, newspaper copy sent from a central location to outlying printing stations, and more, dramatizes the impact of REAL MAT ff r BASIC a CALCULATOR CALCULUS. This space -travel spinoff is sure -fire, so it has a simple guarantee just return it for an immediate refund if you are not astounded at the problems you're solving with it! But the point is - you wont want to send it back. For this is the easiest. fastest shortcut ever! The day you receive your copy in the mail you'll want to put it to - work. Its that exciting and helpful. My name is Dr. George McCarty. I teach math at the University of California. 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Prompt shipment guaranteed. Thank you! ------`` tls EduCALC Publications 27953 Cabot Road, Laguna Niguel, CA 92677 For fast service, hone MC or VISA orden FREE to 18001633.2252, Ext. 340. TOLL aaaaassss ast OIWIB INTEGRATED CIRCUIT THEORY 8 PROJECTS CIRCLE 495 ON FREE INFORMATION CARD With the insight you'll gain from the easy-to- follow explanations and hands -on project instructions included in this exciting sourcebook, you'll have acquired the skills and know -how to begin using IC's in other circuits and applications. Tab Books Inc., Blue Ridge Summit, PA 17214. Paperback, 258 pages. $11.95. 31 e CtoV By D.E. Patrick CONVERTER Beats the socks off any other capacitor meter published to date! Display and control electronics are eliminated! Designed for 1% accuracy! Only one calibration control. Cheap enough for Uncle Scrooge to build! DOVER THE LAST FEW YEARS THERE HAVE BEEN NUMEROUS, ridiculously complicated articles on how to build digital cap rappers (capacitance meters) using capacitance -to- frequency (C to F) conversion in a myriad of experimental magazines. How many? Too many! And they are too complicated, and too expensive! Well, if you yearned for cheap, accurate simplicity, you'd better believe you didn't get that from projects using 555/556 type converter circuits. But, in this article you will discover how to get .1% to 1% accuracy out of just four or five common el cheepo junkbox IC's. In most prior projects, most of your time, effort, and money would have gone into building display and control electronics. However, a DMM is used with this project for a display. The project uses capacitance -tovoltage (C -to -V) conversion, and it's just too simple to pass up. In fact, its name became obvious-C to V Converter. Going Farther Since most of us already own a DMM, using it to display which can still be built out of el cheepo 555- or 7555 -type timers, with expected accuracy in the 1% range or better. Also, using a precision timer like an LM322, we can get accuracies down to the .1% range or better, but let's leave that for another time. Working with the 555- or 7555 -type IC, a C to V converter can be built whose accuracy will be limited by the accuracy of the timers used in a monostable configuration, when triggered by a crystal stabilized clock pulse. However, to cut costs and simplify time -base design, you could use another 555 or 7555 as an astable clock source, and even that configuration could still yield accuracies in the 5% range. So, that brings us to the circuit in Fig. which will work with most DVM's, DMM's, or even high -impedance multi meters for that matter. However, you can't expect the kind of resolution from a standard analog meter that you would get from a 31/2-digit DMM. The full -scale output is volt with a 100% over-range. That is, where l -volt is the full -scale output of a 1000 -pF (102) capacitor on the 1000 pF range, you can actually go up to 1999 pF on a 31/2rdigit DMM having a full -scale range of 2 volts. 1 1 capacitance eliminates the wasted time and effort needed to duplicate what we've already paid for! All we have to add to what we have is a capacitance -to- voltage (C to V) converter, R7 ZERO How the Circuit Works In Fig. 1, Ul, a 7555 CMOS version of a 555 is used as a low power C -to -V converter. U2, a 4069 CMOS inverter, Y1, a -MHz crystal, and associated circuitry, provide a crystal stabilized -MHz clock frequency. Three dual-decade 4518 CMOS counters, U3 through U5, divide the -MHz output. SI selects the trigger input to UI provided by U2 through U5 giving us the ranges 1000 -pF, .01 -1LF, .1 -p.F, and 1.0 -p.F, which may be changed as desired. 1 1 U5 1 R8 CAL U1 J1 32 J2 SI EXT-OFF-BAT J4 J3 Looking down into the the guts of the C to V Converter. The author used a pert -board layout combining some wrapping and point -to -point wiring that suited his construction taste. He opted for an internally connected battery for a power supply, making the unit fully portable. they are mentioned here so that the reader can make changes. The change in duty cycle is what we use to determine capacitance when Ul's output is converted back into a proportional voltage. With R8 properly adjusted and CX = .5 volts. if desired.. which is integrated by C4/R4 into a full -scale output of I volt. However.. In the prototype. SI selects the input trigger signal.20K ~ 2 3 GND V TRIG DISH OUT 7555 CV R 1N4454 TH U1 4 D1 -8 0 +V R11 10052 61 CAL 5 R6J 1 D4 05 Cx 1814003 lpF R9 J2 66K +V 1T Si RANGE +V +V S2 06 15K R7 TEST CAPACITOR 1N4003 C2 tR10 5K ZERO ADJ J1 7 C3 lOOpF 4. when R8 has been properly adjusted with a 10 -ms trigger input. extra switching and two or three values of C4 were eliminated. with a 40% duty cycle.F to 1000 -pf ranges only -µF is required for a stable readout. The longer the trigger and output pulse durations of UI. which is generally higher than necessary. The bottom line here is that C4's value was set to handle the worst case one might find on any DMM on the market today. But.Schematic diagram for the C to V Converter was simplified by eliminating many of the crossing wires.+V o Y1-1MHz orp 00 ---i1 OPTIONAL SUPPLY +V -e 14 13 R^ Df ENA RB Q1A 04B LA +y 11 22T0T33pF Q 4 U2 4069 VDD CLA VDD RB ENA RB 04B Q1A 04E1 03 B 02A 15 A 10 MEG C11 14 100µS 03B Q2A U3 02e 4518 03A 1{d 11 9 TO 12V 8 --. When UI is triggered. On the .10K #R3 2. Now. That is. Also.VS BATTERY 9 8 CLB VS 9 +V o s R5 2. the readout will not read 0000. That reference voltage across D2 is outputted to your DVM or DMM after filtering by C4. As the duty cycle decreases for a given value of less than .1 µF in the example above. L 11 ENB 10 RA 10 A 100pS 02B 01B Q4A Vs _C) 12 +V 7 14 13 4518 0 A 1 15 U5 02B 03A +V C136 U4 4518 10 SPST -o 16 6 CLA 81 9VDCf 1. And.5V OMM OUT 1814003 o J +V 102 103 1000pF . C4 is set at 100 p.5 volts. there will be some stray capacitance such that when C = 0. interconnect all circled points identified by the same letter. with no jitter. the drawing is as close as possible to a wiring diagram with the IC pin -outs in sequential order.1 -µF across J I and J2.7K R12 J4 - DM336 2. and to keep things simple.. its output voltage will swing toward the positive rail. in order to zero the readout.1µF 105 lµF C5 100F 25 V ` EXT BAT OFF J5 TO BATTERY ELIMINATOR / rR13 SELECT CHARGE IF DESIRED Fig.C. we have to make our DMM think we've gotten rid of it. Now.F. almost no filtering is required. UI will provide an output pulse width having a variable duty cycle. It will see only 40% of 2. which would be 10 milliseconds (ms) in the . Therefore. C x R's value could be changed either by a separate switch labeled FILTERING. if you want fast settling or the fastest possible settling time on all ranges. or it could be handled by a ganged deck on Si. Chip UI is configured as a monostable multivibrator with an output pulse width determined by the equation Tp = 1. To assist the wire. UI provides a duty cycle of 4 parts in 10 or 40 %. on some types of integrating voltmeters. which is directly proportional to Cx's value. the meter won't see the reference voltage of 2. the output voltage increases. the readout on the 1µF range is rock solid.01µF 104 . the C longer the integration time necessary out of the low -pass filter made up of R4 and C4. Potentiometer R7 provides the zeroing adjust to compensate for inherent stray capacitance by offsetting the voltage at J4. Without zero compensation.wrapping project builder.2K J3 C4 100NF (SEE TEXT) R4 D3 R2 100K 1N4454 5.IR. however.1 -µF position. As the duty cycle increases for larger values of C. the voltage output looking back into J3 will decrease proportionately.1-p. The value of C4 is not critical to accuracy. since you can't avoid the inherent 15 to 20 pF of stray capacitance. we can 1 33 . and the reference voltage of D2 will appear across R3. but will affect the stability of the readout. there will be a 1 volt output across J3 and J4. A precision capacitor substitution box might be borrowed and used for the same purpose. 2.100 -µF tantalum electrolytic (for max stability of all meters on highest range. But be careful. Still another option is a rechargeable supply that allows for both battery and external power.to 33 -pF ceramic C2 -.2 K 5% units with DMM) R4-100. Another.PARTS LIST FOR C TO V CONVERTER R11. . wire.4.000 -ohm R10.wrapped.5000 -ohm. if a 5 %Ic tolerance reference capacitor is used for calibration. low.Megohm R2.100 -p. The circuit is all CMOS and uses only a small amount of power. who always has those expensive cap rappers on display. and probably cheaper. Thus. obviously final accuracy of the instrument would be severely impaired. there is nothing critical about construction of the C to V Converter. 5% units except where specified. a standard 9 -volt battery can be used However. using the pictures provided as a construction guide. U5-4518 CMOS dual counter integrated circuit U1 RESISTORS (All fixed resistors are 1/4-watt.100 -ohms. providing not only an indication of absolute accuracy. or a circuit -board developed. but it is not required. because we opted for switched trigger-frequencies so as not have a maze of trimmer potentiometers.1N4003 rectifying diode to match charging current (optional) -7555 or CMOS 555 timer integrated circuit U2-4069 CMOS inverter integrated circuit U3. you should use a reference capacitor in the 1ch range. '. -9 -5 two black J5-Jack to match external plug -pack power supply S1. decals.2200 -ohm.100 -pF ceramic C1 C4. and RI should be placed as close to U2 as possible. -4 construction practices.10.1 -µF ceramic C3. or 1N914 diode D2. especially those to offboard controls such as zero and range.%e gotten LAcr)thing thrown together. linear. Crystal YI. single -throw rotary switch Plastic case. 1% (can be selected from 5. Cl.1 K 5% units with DMM) R3. any unregulated.50. At the very least. usually taken close to full scale. hookup wire. therefore. 1% (can be selected from 2. tantalum electrolytic ADDITIONAL PARTS AND MATERIALS B1 -volt DC NiCd battery J1 -J4 -way binding posts or banana jacks.1 -µF ranges-see text. two red.000 -ohm.) C5. double pole. you'll need to calibrate the C to V Converter by adjusting the CAL ADJ trimmer potentiometer.700 -ohm R13. A lot of those so.000-ohm R5-2200 -ohm R6-4700 -ohm R7. R8.Single pole. Don't forget that. For example.LM336. 10.5 -volt Zener diode D4. 1N4454. Saunter on down and calibrate yours against the best one of theirs. plug -pack power supply.taper. D3-1N4448. but linearity. too! Finally.D6.F.ripple supply from around 9volts to 12 -volts should work. solder.Charge current limiting resistor-select value SEMICONDUCTORS D1. there's only one calibration adjustment. calibrated accuracy will depend on the reference capacitor used more than anything else. linear -taper potentiometer R8. etc. etc. The circuit shown can easily be breadboarded. U4. The latter method can be used to check accuracy at several points on a given range. The simplest way to proceed is to use a capacitor of known value covering as much of the full scale as possible. and fool the DMM. 1 -11F adequate on 1000 -pF to .) R1. Unused inputs of U2 should be tied high. center-off toggle switch S2 -pole. knobs. Only a single capacitor is required here (unlike the case with many other designs). Construction Hints Obviously.called service -grade units have accuracy specifications worse than %.to 15 -turn trimmer potentiometer R9-68. it can still have laboratory quality potential. Connect the capacitor to the binding posts on the left and the DMM to the binding posts at right. 25 -WVDC. Some Final Notes Once )ou.5100 -ohm. approach is to go down to your local parts and test-equipment supplier. On the top surface are the range -selector switch S2 and ZERO adjust potentiometer R7. although you might have built the C to V Converter out of junkbox pans. Use good standard R7 S2 ZERO RANGE CAPACITORS -22.'2 -watt R12. Keep hookup wires as short as possible.000 -ohm etlectively negate stray capacitance picked up at JI and J2. I JI 34 J2 S1 EXT OFF BAT What's up front and top is all you need to operate the C to V Converter. Another alternative is to use a rechargeable NiCd or standard battery with external backup.15. can be reduced on most meters to reduced setting time. 22. The tone generator's frequency drops to its lower design value when CI discharges and produces the falling edge of the sawtooth.- 1P1 10R4 20 a B C R5 '22K R3 0 R7 11 r E 47052 i '22K R2 R6 Cl 111111 R4 220K R2 10052 C2 OUTPUT QI Ill. 02- I 2.O000 . 1/4-watt. about once each second. - OUTPUT .N. you not only hear it: it drives you nuts). (With all the high frequency components in the output.01 -1iF. sub-audio frequency. operates at a fairly high audio frequency. Fig.frequency sawtooth from Ql directly across capacitor C2. 276 -2029).I o rr - RÌ A1 . That causes the frequency of the tone generator to increase. Sawtooth waveforms are produced at the emitter terminals. 2.L.. R7. operating at a much lower. The frequency of each oscillator is determined by the values of the resistor and capacitor in its emitter circuit. One. Whee. Scott Without R4 connecting the two emitters. The Yelping Siren shares a Global Specialties type il)I) solderless board with a small audio amplifier. Speed up the control oscillator and set Q2 to around 800 Hz. etc.C. When R4 is connected between the two emitters. In the circuit. 1/4-watt.100 -ohm." TV series. F. the other is the control generator.000 -ohm. R5. depending on the effect that you want.circuit board duplicating the connection terminations of the solderless board can be used later to hard -wire the unit. Inside the Circuit The circuit arrangement in Fig. it couples the low. I is a popular one. 2N2646. Boarding It The layout of components for the Yelping Siren is sho n in Fig. based on circuits in unijunction transistor application notes from Motorola and Texas Instruments.470 -ohm. 1 -The schematic diagram for the Yelping Siren is easy to understand when you omit resistor R4 and study each half of the diagram.Assemble the Yelping Siren circuit provided in 1 on a solderless breadboard the first time. You may want to add an audio amplifier. MU 4891 (Radio Shack No. Ql operates in the I to .Irr TO THE BR11ish hee -haw police siren that many of us first heard on the "Man From U. With the time constants shown. General purpose unijunction transistor. (The amplifier is described next). 10% resistor R2. each oscillator operates independently with its frequency determined mainly by the RC time constant. unijunction transistors Ql and Q2 are both connected as relaxation -type. That is sufficient to drive a small output transistor or a low-power audio amplifier. 1/4-watt.F electrolytic across CI and you get a Whoop Whoop -Whoop that you can associate with a destroyer's siren as it charges a submarine in the movie Victory al Sea.01 1 B1 B2 Fig. R1. This siren produces a sawtooth output signal with a peak to -peak voltage equal to approximately half the supply voltage. the tone generator. play one against the other. E MU4891 2N4870 2N4871 MU2646 2N2646 2N2647 2N4851 2N4852 Fig.. Transistor Ql is the low -frequency control oscillator and Q2 is the tone generator.5 -Hz range (you can't hear that frequency) while Q2 is operating in the 400 -500 -Hz range. 10% resistor R3. and you hear the more demanding Wheep . 10% resistor C2. R6.. I } +9VDC +9v .E. two -tone pulsing and warbling sirens consist of two oscillators. 2N2647. Basically.YELPING SIREN Take two oscillators. along with the rise in sawtooth voltage from Ql. sawtooth oscillators. PARTS LIST FOR YELPING SIREN 50 -WVDC electrolytic capacitor disc or metallized -polystyrene capacitor 01.. 35 .Wheep -Wheep. Shunt a l0 -p.li1111110 R6 ' T C1 4. MU2646. QI operates at about I Hz and frequency -modulates the 500 -Hz tone to produce the familiar Whee -O000. Then insert R4 and see how the lower frequency affects the higher frequency.7 i 10052 OO ges . 2N4870. and hear them sound off! By Robert LITHE YELPING SIREN IS SIMILAR IN COtic'1. The control frequency modulates the tone generator or pulses it on and off. A printed. With the values shown. or less. See Fig.-. little job that'll do the trick! We call it the Low-power Audio Amplifier! Designed around the Sprague ULN -3705M lowvoltage..to 32- AUDIO INPUT +Vcc(+3 TO *12V) R1 VOLUME C3 100K 0. I. the 10 -dB cutoff points are at 20. and power -supply ripple rejection.5 -in. UI. and 60 Hz.There's nothing to it! The Low -Power Audio Amplifier consists of one chip and six other parts. 16 -. . power output is 450 milliwatts with an 8-ohm speaker. POWER SUPPLY GROUND -1 1 --.to 3. Should the output level be set to a fixed value. and 240 milliwatts into 16 ohms. when C4 is 500 ILF.500 + 500 .) Inside the Circuit Components external to the integrated circuit.1. consist of four capacitors and a potentiometer for volume control. . Capacitor C3 is for decoupling.1 C1 8 NC NC I7 16 001 2 3 ohm speaker that is efficient. the unit is also suitable as a low-cost. ceramic disc capacitor R1.frequency roll -off. Capacitor C4's value is selected for the desired low-frequency roll -off with a given speaker impedance. shielding of all signal leads is necessary. and 310 milliwatts into a 32 -ohm speaker. power-amplifier chip. (Continued on page 96) - Fig. You can use a speaker with impedances of 8 -. the output is 600 milliwatts into 16 ohms. 10 -. The lowest impedance produces the highest power output for a given supply voltage. ` Ut C v CX . respectively. That shield reduces noise. The parts are so positioned that they can share a board with the Yelping Siren. hum and feedback pickup. Higher impedances reduce harmonic distortion. } SPKR1 -8. and operates (with reduced volume) from supply voltages as low as 1. C4 C2 -. 1. low. The input lead to potentiometer RI is shown shielded in Fig.000 -ohm. ceramic disc capacitor C4-500 35 -WVDC. PARTS LIST FOR LOW -POWER AUDIO AMPLIFIER C1.ULN -3705M audio amplifier IC (Sprague) 36 SPKR1 -1.001 -RF. Values up to 200. 250.1 -µF. diameter U1. audio. 1.F. With a 9 -volt supply. With a 6 -volt supply. compact alternative to an equivalent audio amplifier using two or three discrete transistors in other projects. or 32 -ohms. (It's power requirements make it suitable for solar-cell application. then the shield lead is not necessary..000 -ohms can be used. 1--C1-re --C1 SPK R1 8 -3252 . if the amplifier circuit is assembled on a breadboard with a siren (the one tha preceeds this article). Capacitor C4 is an electrolytic type that couples the audio output to a 8.100. between input pin 8 and ground is ideally 100. . or a selected fixed resistor. the components may be encapsulated in epoxy and secured permanently to the speaker metal frame. The volume -control potentiometer. With an 8-ohm speaker in the circuit.AUDIO AMP pöER With only 6 external components this amplifier delivers the sound you need! By Robert E Scott ['YOU HAVE JUST BUILT THE YELPING SIREN AND WOULD LIKE some zonk power into a loudspeaker.000-ohms. Here's a simple. Should the input circuit and potentiometer RI be mounted off the board. and 100 µF. Here's how the Low -Power Audio Amplifier looks wired on a solderless breadboard. The speaker's diameter ranges from 2 to 5 inches. However. 2. electrolytic capacitor C3-0.to 32 -ohm speaker.8 volts without having distortion rise to unacceptable levels. RI. The Low -power Audio Amplifier operates from supplies ranging up to 12 volts. AUDIO INPUT 1Ati 1 + r-r C3. audio-taper potentiometer C2. 30. . 2- Fig. . 'I CHNICAL TRADE IBM is a Registered Trademark of International Business Machines Corp. If card is missing. circuit board by circuit board unit by unit. how they operate and are used to solve problems. Learn servicing of monochrome and color TV receivers. 4 open slots provide for Your NTS training course will teach you how to program on this powerful PC using lessons. Home Appliances. 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IF You WANT To GET INTO PC SERVICING YOU HAVE TO GET INTO A MICROCOMPUTER Learn PC Servicing By Building Your Own NTS /HEATH HS -151 Desk -Top Computer NTS lntronic home training gets you right down into the heart of com- puter circuitry. Video Technology: Build the NTS/ Heath System 3 advanced Color TV as you learn circuit diagnostics. MS is a Registered trademark of Microsoft Corp SINCE Resident and Home Study Schools 4000 So Figueroa St . This power trans- lates into high speed operation. CA 90037 . NTS Offers Many Additional Courses in Electronics. will accept most peripheral boards designed for IBM PC. Los Angeles. expandable to 640 KB. expansion. Hero 1 TV and Radio Servicing: A spe- cialized course featuring training in both analog and digital test equipment. NTS also offers courses in Auto Mechanics. Learn how microprocessors function. 3. To better understand the parameters involved.1 02 = 0. virtually no current is being drawn from the solar generator and the resulting voltage can be considered equal to the open circuit voltage-the voltage produced by a solar cell when no load is applied to it. that voltage may vary slightly from cell to cell. When designing or building solar-powered projects. As we decrease the potentiometer setting. Also. making electricity from sunlight. It is approx- 03 04 VOLTAGE (VOLTS) 40 VARIABLE CURRENT 1.WORKING WITH SOLAR CELLS IS LIKE WORKING WITH ANY other power supply. though.1) to demonstrate the solar cell's characteristics. A passing cloud. Consequently. those factors must be taken into account. And. the output characteristics of the solar cell are dependent upon the amount of light falling on it. Of course. as everyone knows. Photovoltaic Characteristics Whenever using any power source. Each kind is designed to deliver a certain amount of current at a given voltage. sunlight is erratic at best.0 100 mW/CM2 1 SUN 75 mW/CM2 = 0. in more detail.75 SUN 0 0. testing is important if we are to obtain the maximum performance from photovoltaics-the process of 1 -A family of curves showing the relative output characteristics of a solar cell under varying sunlight conditions. let's first take a look at the silicon photovoltaic cell's characteristics. 2. Unlike conventional power supplies. Looking at Fig. 2.50 SUN LOAD Fig. or 600 -millivolts. In most cases. by using the circuit in Fig. can reduce power output by more than 50 %. not all cells generate equal amounts of current under the same lighting conditions -even when the cells are identical in size and construction. silicon solar cells are nonlinear devices. Fig. Ohm's law establishes the relationship. for instance. Unfortunately. you see that we are monitoring both the voltage and the current output of the solar cell as it passes through a variable resistance load. We will assume that the light intensity is stable for the duration of = 0.7 imately 0. and there is no simple formula expressing that relationship.volts.0 25 mW/CM2 VOLT AGE 1 = 2. and manufacturer to manufacturer. . We begin by turning the potentiometer to its maximum resistance setting. To further complicate matters. Variations in the manufacturing process can cause the cells from the same batch to vary widely in their output currents. Instead.6.Diagram of a simple solar cell tester. 2. it is imperative that we understand how the voltage and current interact with each other and with the load.25 SUN the test. we can explain the electrical behavior exhibited in Fig. In that mode. we will use a family of easily understood curves (Fig.0 50 mW/CM2 CELL UNDER TEST 05 06 0. flows through the entire string of cells equally.3 04 0. with each cell adding its small voltage to the whole.45-volts). At one extreme. happens to coincide with the knee of the current curve seen in Fig. A point is reached where decreasing the load resistance no longer causes an increase in the output current. The cells are chained in a long string. In essence. an accurate way of evaluating the performance of a silicon solar cell would be to load the cell under operating a 02 01 0. Current matching of solar cells should be within 5% and shouldn't exceed 20 %. The current. Power is calculated by product of the output voltage (in volts) and the current (in amperes). you ask? Well. 3. Therefore. adjust the voltage with the potentiometer. 41 . and rightfully so. Fig. which was plotted as the top curve. however. because without voltage there can be no power.ampere cell you can only obtain 1 ampere from the combination of those two cells. Because the output voltage of an individual solar cell is a mere 0. The fact that the entire family of current curves have the same shape means that we will always realize peak power at the same voltage. Finally. Individual differences in the voltage output of any one solar cell is of little concern. Power Curve If we were to plot graph of the voltage in relationship to the power output. we have maximum current with no voltage. but it will not shift with respect to voltage. And the current seeks the level of the weakest solar cell in the chain. however. the The Need to Test Solar Cells The need for matching solar cells becomes most apparent when assembling a solar module of many solar cells. due to the weakest cell.'. no power is produced at that point. But what about the voltage. Designing a Tester As we have already demonstrated.CURRENT the load across the cell increases. Simply place the cell across the circuit. if we place a 2. If. that current value is known as the short circuit current. 2 to test your solar cells. For instance. Each successive curve was derived from the same cell at progressively reduced light intensities. For our first measurement we have taken the liberty of assuming that the highest radiation level was used.current output. as it o should with an unregulated power source.ampere cell in series with a 1.25 volt of the desired level.volts. In other words. So far there is nothing out of the ordinary. each cell is a little different. Should the module's total voltage be too low. conditions so that its output voltage equals 0. does the solar generator produce peak power: It is at that point where all factors come together to provide the most power from the cell. By the way. which incidentally. Between those two extremes the photovoltaic cells produce power. The power peak occurs at about 450. the voltage begins a gradual decline that is proportional to the increasing load. or addition. resulting in the same no -power condition. The heavier loading causes the output current to increase. or too high. As a matter of fact. All voltages will be tallied in the end.6 VOLTAGE (VOLTS) 3 -The relationship of output power of a solar cell compared to the cell's voltage. several cells must be wired in series to produce a workable voltage. it would look something like the one in Fig. all the cells are matched with regard to their output current. using that method. Of course. the voltage drops to zero as the load resistance becomes zero. our solar generator has become a constant current source. At the same time. much as it would do to a battery under the same conditions. Only at one point. Therefore. the subtraction. a short circuit across a photovoltaic generator does no damage to the cell. The problem arises when cells of different current-capabilities are wired in series. Not only are all cells compared on an equal basis. that is a quick and easy to do it. the cell's output voltage shows a slight decrease. it takes at least 30 cells to make a 12 -volt photovoltiac module. each cell will be driven to its peak potential. we have maximum voltage but no current. Obviously you are losing potential power.5 0. At the other extreme.millivolts (0. on the other hand.right on down to an absolute short! In fact.5. you can use the circuit shown in Fig.45 -volts and take a power reading. regardless of the solar illumination. and note your readings. but individual cell performance can be judged at the same time. Then something strange happens. the actual power will depend upon the solar radiation at the time. of a solar cell or two will restore the voltage to within . The amount of current that the solar cell can produce is a function of the light intensity. No amount of loading will extract any more current from the cell once that point has been reached. and maximum power will be realized from the array. However. Of course. suppose you have to test 30.Megohm 42 R9. Now.000 -ohm potentiometer ADDITIONAL PARTS AND MATERIALS C1.033 -ohm (see text) R14. R12.F.03352 Cl 5 A. R3. 50 -WVDC Ml. 0.position rotary switch Cabinet.Megohm R5-220 -ohm R6.voltage regulator.LM1458 or MC1458 dual op -amps 01. the transistor can be thought of voltage holds the desired value.establish the operating voltage. printed. R7. or 40 solar cells.3. Regardless of the voltage initially presented to the input. you must adjust the load resistance to re.10. current control is still a problem in the transistor's base circuit. indeed! A better scheme would be to find a way to automatically adjust the base current without having to manually compensate for it each time. What could be better than a transistor? A transistor makes an excellent substitute.5. 4.1. produces a large current change at the collector. the transistor suffers from the same shortcoming as the potentiometer. resistance required to stabilize the cell at its peak power point will vary. 1/4 -watt units) R1.000 -ohm (see text) R8. M2-0 -1 mA panel meter S1-Single -pole.1 -p. solder. we still have to fine tune the base current as we switch testing from one cell to the next. An effective way of reducing that problem is to isolate the load resistance from the adjustment. Unfortunately.ECG187 silicon. A small current to the base of the transistor. The regulator works by comparing the input voltage from R10 o +IN 750K 100 mA R9 AA 10K R8 3MEG +12V 3A 0 Si RANGE R12 *-MV.910 -ohm R13 -.LM1458 R4 1MEG O-IN y 100K R3 CELL UNDER TEST 500 mA 91052 R6 10K A/V` R1 10052 O1 =1N914 { S 1 T R13 +12V 0. the power produced by the solar cell must be dissipated entirely by the potentiometer. audio -power transistor D1 -1N914 signal diode RESISTORS (All fixed resistors are 5 %. the shunt regulator will adjust its shunt resistance so that the output CURRENT VOLTAGE ADJUST 4-A transistor is used to load the solar cell under test in place of a res'stive load.50. etc.2-0. as shown in the circuit of Fig. wire.1 R7 10K = R2 R11 M1 91052 VOLTMETER Q1 10K ECG187 -W M2 AMMETER R14 50K CALIBRATION BC -12V E Q1-ECG187 PARTS LIST FOR SOLAR -CELL TESTER SEMICONDUCTORS U1.000 -ohm R4. What we need is a shunt. The base current effectively changes the resistance of the transistor.as a dynamic resistor. A shunt -voltage regulator is a closed -loop controller that uses the input voltage to control the base current. Fig. That is. or more? It would quickly become a time -consuming task. A 220ohm resistor (R5) limits the base current to Ql. 3.000 -ohm R11. How the Circuit Works The finished product of our design appears in Fig. PNP.100 -ohm R2. In that particular application. Solar Cell Holder. Although this circuit eliminates the problem of a heating load resistor. Furthermore. You'll see that an operational amplifier (U1-a) has been put in charge of controlling the transistor's base current.10.circuit materials. And accordingly. with the resultant heating affecting resistance stability.750.100. . which in turn is used to load the solar cell. U1 .000 -ohm R10. Although the Solar -Cell Tester can be built using any conventional form of construction. That gain produces a I -volt output from the amplifier when 500 -mA flows through resistor R13. By its very nature. identical to M1. Resistors R6 and R7 feed the differential voltage to the inverting and non - inverting inputs. The tap voltage can be adjusted anywhere from zero volts up to + 0. Zeners in that voltage range are either very temperature -sensitive or expen- sive-usually both. Similarly.millivolts. In our circuit. Multiplying one reading by the other nets you the power in watts. Ammeter M2. which is 100. on the other hand. Monitoring the voltage 1 across R13 is a differential amplifier (UI -b). Current flowing through R13 produces a voltage drop across the resistor. The case formerly housed a CB SWR.7volts. Resistor R4 sets the gain of the amplifier. By forcing current through the shunt regulating transistor Ql until its resistance drags down. which is forward -biased by resistor RI. Construction You don't have to get as fancy as the author did in finishing off the construction of the Solar -Cell Tester. a small one. The voltmeter is pretty straightforward. we have extended the limit of our current meter from 100 mA to 500-mA.limiting resistor-R12 -that indicates -volt at full scale. the input Monitors teristic limits our regulating range between +0. It is a 3Megohm resistor that sets the gain of the amplifier (UI -b) at 300.and +0.voltage reference source. The voltmeter converts the voltage from the amplifier into a current reading where I volt equals 100 mA. The output voltage from the differential amplifier is measured with voltmeter M2. The reference voltage is fed to the non -inverting input (pin 3 of UI -a) of the amplifier. The inverting input senses the photovoltaic voltage through resistor R3. paralleling R9 across R8 gives us a 0 -3 amplifier current meter. Our reference diode (DI). Normally.circuit board that can be used to assemble the Solar -Cell Tester. the use of a printed -circuit board is strongly recommended. our amplifier circuit attempts to maintain the inverting input voltage equal to the voltage at its non inverting input. respectively. that would require a Zener with an extremely low voltage. makes an excellent low. Unfortunately.7. RIO. the reference source is established by a Zener diode. it is impossible for a transistor to achieve zero resistance. The gain of the amplifier (UI -b) is controlled by resistors R8. So a small residual voltage lingers. . Actually. The circuit is arranged so that the emitter current of QI must flow through resistor R13. on the other hand. R9.milliampere panel meter with a series. When RI0 is placed across R8. Resistor R8 is a fixed value that is permanently connected across the output and inverting input. establishes the voltage range of the regulator by limiting the voltage across CALIBRATION potentiometer RI4. The current passing through R13 reflects the current magnitude generated by the solar cell.Same -size foil pattern for the printed. In effect. 6. A forward -biased diode. Voltmeter MI monitors the voltage developed by the solar cell. uses an operational amplifier (U1 -b) to measure current flow.approximately 150. pin 7 when 100 mA flows through R13.15. That charac- the cell under test to a reference voltage. + IN IN voltage will equal the voltage at the tap of R14.6. With a gain of 300 an output voltage of I -volt is developed at UI -b.volts. the amplifier's (UI -b) gain is reduced to 60. Fig.antenna test device. albeit. while ammeter M2 measures the current flowing through the shunt transistor. preferable under l -volt. It is a 1. A foil pattern of the board is shown in Fig. Use a pencil as a form and coil the wire so that it fits comfortably on the board. It won't take you long to find two that match. But you can make R13 with a 4 -inch length of #30 wire-the same wire popularly used for wire wrapping.circuit board. the CALIBRATION control (R14). Notice that the shunt regulating transistor Q1 mounts on the increasing its accuracy. The grid (Continued on page 102) IN 100pF T16VDC BRIDGE 117 VAC RECTIFIER 7812 l OUT +12VDC GND 1 -12VDC 100pF 16 VDC Fig. The back contact of the cell is the positive output. For more automated testing. if you wish. M2). on the other hand. so I recommend getting a handful of 10. those supplies are not critical. Their common junction represents ground. Firmly bolt the transistor to the large copper pad which serves as the heat sink for Q1.) Resistor R13. Observe semiconductor polarity.000 -ohm resistors that closely match and place pairs in parallel.circuit board showing the foil pattern underneath and the parts location on the top surface of the board. which may be of assistance to you. A flat aluminum plate slightly larger than the cell itself could provide a good back connection. The two meters (M1. is not a conventional resistor. A schematic of a suitable supply is shown in Fig. The instrument is powered by two power supplies: +12volt positive and 12-volt negative. You can power the tester with a pair of 9 -volt transistor batteries.Fig. M1 500 mA 3A o 100 mA ° S1 RANGE CELL UNDER TEST 1 R14 CALIBRATION a piece that is just slightly longer than four inches. 7 -X -ray view of the printed. The exact value of R13 is quite critical in determining the accuracy of the current meter. while a test probe borrowed from a VOM makes a nice front contact. Here you have to use your imagination.000 -ohm resistors and measuring their value on a digital multimeter. Connection to parts external to the board are detailed. However.Typical dual 12 -volt power supply. Probably the most difficult piece to obtain or fabricate for the tester is a solar-cell holder of some kind. Now I realize that precision resistors are both expensive and hard to come by. The Solar -Cell Tester circuitry may be housed on a breadboard or in a chassis box. R6 and R7 should be a matched pair. foil side of the board. and trim it back as you monitor the current indication on M2. GND + 10pF 16 VOC . 7 and solder them in place. 8. 44 8. you might want to consider buying or building a test jig. thus Insert the components according to the parts layout in Fig. all you have to do is insert the cell to be tested into the tester and take a reading. resulting in an averaging effect to bring the respective resistive pairs closer together. neither is their voltage. Cross Match One. Ideally. and it goes to the positive input of the tester. Another trick that you can use is to find four 20. You might want to start off with - Using the Tester Using the solar-cell tester couldn't be easier. I seriously doubt that you could find one in popular stock. and the RANGE switch are mounted in a suitable cabinet along with the printed. No insulating washers are necessary. (In this issue we have a project. Your castaways can be used for R2 and R3. Basically. there will be a null output. Few of us can afford to run out and buy matched resistors. Potentiometer R3 in the feedback loop of UI will determine expected tolerance limits. R1 and R2. 5 %. But even fewer of us own expensive laboratory-type equipment like Wheatstone. 1 -The two input resistors. if above 2000-ohms. where if RREF = RSAMPLE and R1 = R2.1V 2N3904 45 . The other two legs of the bridge are formed by two other matched resistors. . WHEN How It Works The circuit in Fig.1% matched'resistors and the like.. That is. That device works like an expensive production line tester to select resistors. 10K (SEE TEXT) 01 )Q1 81 9VDC 1N4733 5. I is basically a null. A standard 9 -volt transistor battery or chargeable battery should be used. The project relies on the principle of selecting a sample resistor that is within some tolerance of another reference resistor. J1 R4 l R1. although the value. and impedance bridges. you don't have to make ten different settings on some expensive bridge. cross -matching resistors will be a tedious task at best. one arm of the bridge might be a cali- FACED WITH BUILDING COQKBOOK INSTRUMENT amplifiers requiring 1% to . So. the voltage drop across R8 and R9 cut off Zener diodes Dl and D2. and the Cross Match brated potentiometer or precision decade box for direct readout.1 %. etc. in this application.detecting bridge with LED readouts instead of a meter. the differential input to Ul is at a null.emitting diodes LED2 and LED3.E. Two legs of the bridge are formed by the selected reference resistor and chosen sample resistor.emitting diode LEDI will be lit. respectively. When Q1 and Q2 are conducting (see Fig. I). even when we are lucky enough to find them locally. easy -to. The extent to which the RREF value approaches the RSAMPLE's value will determine where the OVER or UNDER light. plug in your reference resistor. In a standard Wheatstone bridge. even if you own an expensive bridge.5 volts for a 9 -volt battery input.CROSS MATCH ONE By D. A cheaper solution would be to select them out of your junkbox. %. Kelvin. Further. However. you set the tolerance desired at 10 %. we are using a balanced bridge that does not provide a direct readout in Ohms. which does not have to be regulated. 10K R REF $ 41052 Q2 (SEE TEXT) BALANCE 09 2 -3 MEG 10012 IN 2K 2 ALTERNATE TOLERANCE ADJUST (SEE TEXT) OVER LED3 LEDI 111 UNDER Dz ) \\ 5 2 02 1N4733 2N3906 R3 LF356 S1 4 J3 (C R6 2K RSAMPLE J4 ¡ ¡ ON/OFF R8 100 R2. with simple. and there's no waiting around for some slow 5 -digit readout to settle in. UNDER. When the bridge is balanced. the average project builder or electronics experimenter is generally out of luck. as opposed to measuring actual resistance. so the 1 Fig. Patrick Match resistors to better than 1% accuracy-no meter needed! One's three LED readouts indicates OVER. Voltage regulation is not critical for proper circuit operation. The output of UI will assume a mid -range value of the applied voltage and its output will be around 4. 5 -digit DMM. Under those conditions both transistors QI and Q2 will be turned on and the IN TOLERANCE light. is not critical.interpret LED readouts that will allow you to select resistors at the rate of one a second or better. There's no analog meter to interpret. will be lit. et al. it's a better way to go even if you own the kind of premium stuff that few of us can afford. for the Cross Match One should be matched. Another and better solution to the problem is the Cross Match One. and IN TOLERANCE. 1 -W LED1 -LED3. The prototype shown was built out of my junkbox into a Keystone plastic box. IN LE01 INTOLERANCE CURVE Q1 UNDER LEO LED1 LED2 LED3 R3 B1 OVER LED3 2 OUT OF. Keithley.emitting diode. where the width of the skirts and sharpness of the curve will obviously be dependent again on the setting of potentiometer R3. several distinct tolerance ranges can be chosen by adding a switch and several trimmers or fixed resistors in place of R3. (Continued on page 96) .emitting diodes can easily be seen without the necessity to drill front panel holes-but that's optional. Old tube -type Fluke. 5. OVER and UNDER Construction Hints There is nothing critical about construction of Cross Match One. solder. etc. However. That condition aids in defining the skirts of the in-tolerance curve.Matched resistors.Light.to 3. 20 -mA.emitting diode will come on. R2. in RSAMPLE above or below REEF that must occur to light the respective light. red Q1. only that they are closely matched. No critical components are required. (see text) R4.emitting diode will be lit. J1 S1 -SPST toggle -9 The only things that might give you a problem are resistors RI and R2.emitting diode operation is detailed here.emitting diode is set by R3 in Ul's feedback loop. as shown in Fig. perfboard. the parts can be identified. the sharper the tolerance curve can be made.000 -ohm used in prototype -see text) R3 -2. absolute value not critical. differential voltmeter. R6 -2000 -ohm R8. et al differential voltmeters. Their actual absolute value is not important. A piece of scrap Plexiglas clear sheet plastic was substituted for the standard cover.Megohm potentiometer for gain adjust. But when the differential voltage at UI's input increases or decreases out of some specified tolerance. R7-470 -ohm R5. The better that match. 2 -The response curve for light. IN. so that the light. transistor -radio battery Plastic case. The RREF and RSAMPLE banana jacks (J1 -J4) were mounted on the side of the case with ON /OFF switch SI and BALANCE (gain) shaft of R3 sticking out the top. which we'll get to in a moment. The tolerance. Thus.emitting diode is lit. And the easiest way to lay your hands on some closely matched resistors is to rip them out of a junked Kelvin -Varley Bridge. The degree of overlap depends on the gain of the op-amp. clear Plexiglas sheet. the simple one op -amp circuit is easily breadboarded. The circuit will then have a response where UNDER.2N3904 NPN transistor Q2. or OVER light.Fig. hardware. either QI or Q2 will turn off and the OVER or UNDER light. We can easily see that there is an overlap area under the inToLERANCE curve such that OVER or UNDER light -emitting diode may also be lit when the IN light. options such as a rotary selector switch and additional resistors are left up to the project builder who wants to customize the unit to suit his needs. the type you can get at any Radio Shack store. except resistors RI and R2. old nixie tube DVM. The unit can be built right out of most junkboxes at zero or nominal cost. Fixed resistors and or trimmers may be added along with range switch if desired.1 -volt. it would be a good idea to wire neatly. or R3 could be a calibrated potentiometer. 2. R9-100 -ohm ADDITIONAL PARTS AND MATERIALS -J4-Banana jack switch B1 -volt. And. That kind of stuff abounds at any surplus store. as we can see in the photos provided. or range of change. decals. RTV cement or epoxy. D2-1N4733 Zener diodes.2N3906 PNP transistor U1 -LF356 op -amp RESISTORS R1. et al.TOLERANCE CURVE U1 02 OVERLAP OVERLAP Without taking the cover off the Cross Match One. especially if you know what you are looking for. light -emitting diodes will be held oft. 46 12 J4 J3 PARTS LIST FOR CROSS MATCH ONE SEMICONDUCTORS D1. Since the project's interior can be seen. The diagram is not drawn to any scale. (10. hookup wire. it should indicate that the system has approximately 15. a system that displays only 12 volts is already in trouble. then battery potential will be less than 12 volts. A close examination of Table I will show that if either of the leftmost red lamps are lit. It will also be apparent that when the engine compartment (and alternator) become warm. Summertime temperatures will prevent automatic ad- -a MON= vance in charge rate. which is just the effect we desire. On the other hand. Such high. By all means. By noting what the voltage of your battery is at night when the car is put into the garage. because batteries do not require as much charging voltage in the warm weather.charging rates should be investigated before expensive replacement problems occur. When the third lamp (yellow) is lit with the vehicle unused overnight. if the voltage drops overnight to less than 12. If the readers should monitor voltages for a length of time. Putting It Together Circuit construction is very simple and inexpensive. Lamps numbered from 4 to 8 are green and will show the normal operating range of the system you should anticipate. Once again. the system's regulator automatically considers the temperature and will kick the voltage up to the higher charge rates.8 to 14. when charging voltages are in excess of 14. by coming on when the voltage is low. It is well known that batteries require a higher charge rate in cold weather than they do in warm temperatures. then most likely the battery is bad. In fact. if the voltage is 12 volts or less. the charging voltage will once more drop to about 13. or sits there ready to blink on just as the battery dies.Aim lilik - ' ' 'r ` BAT By Warren Baker IBINATOR IF YOU ARE ONE OF THE MILLIONS OF AUTOMOBILE DRIVers in the country who have experienced a dead battery in your car.8 volts or so. then it may indicate a possible alternator defect. On the other hand.7 volts in the normal driving range. and once again in the morning when you enter the vehicle. you can be wary of the battery's ability to see you through the winter weather if you reside in the colder climates. Depending on the status of the engine (off or on). and other high -current devices turned on. by indicating abnormal behavior. In reality. then the Battery/Alternator Monitor project described here may be just the gadget you have been searching for. Whenever lamp number 9 lights. It will be seen that in wintertime driving.1 volts being generated. or. up to about 14. it may show a borderline charging rate. the monitor can forwarn the owner of impending battery failures at least six months in advance. The last lamp is again red. the design and assembly of the first Battery/Alternator Monitor was generated by just such an occurrence defective alternator. perhaps an extra heavy drain on the electrical system. it is possible to determine the condition of your battery. if the red lights are lit with the engine running. there is another interesting event that takes place in most automotive electrical systems. as outlined above. In addition. damage to the battery may occur-and not become apparent until after the battery exhibits a failure. the battery voltage may drop below the 13 volts. For instance. If the car is idling at a stop light with the heater. In most cases a warm engine and a fully charged battery will show in the 14 -volt range and lamp number 6 will be lit. The following discussion outlines a method to easily duplicate the .2 volts and remain steady.6 volts) a diagnostic service should be performed as soon as possible and corrective action be taken. The battery voltage should immediately return to a higher voltage when the engine is speeded up. it will warn of a charging circuit problem even when the idiot light system has failed. When installed in your vehicle. Over a period of time.5 volts for long periods of time. because if your system reaches that voltage level (15. If the battery has been unused overnight. you should be confident that your battery is in relatively good condition.5 volts or so. some corrective action should be taken before you stall on the road with a dead battery. The idiot light should tell you that. headlights. most vehicles' electrical systems will average anywhere from about 13 volts to as much as 14. Voltages less than 13 volts will usually indicate a charging. when it is illuminated while the engine is running. That is a bit high and the owner should have some corrective action taken. the chart will outline problems to be expected. When the Lights Go On The Battery/Alternator Monitor will provide an insight to all the above problems and perhaps more.system problem or a current drain on the system that the alternator is unable to overcome. Most everyone in electronics will be aware that battery voltage in automobiles will vary considerably from the 12 volts usually considered to be normal. 0 On 5 Grn. take the main board and place it with the single row of holes against the LED board's edge. I. 3 first. Cutting the boards from a piece of Global Specialities EXP -300 PC printed. Refer to text for tips on cutting the board.system should be checked Volts Lamp 2 Red 12. sand the rough edges of the boards to a smooth edge. Then. It is now time to begin wiring the main board. using a razor held in a handle designed for that purpose.5 Off Bad or discharged battery Unused overnight slight battery drain On Alternator problem Find repair shop immediately Off Weak or bad battery Unused overnight On Alternator problem Service is required Off Good battery Unused overnight On Borderline charging or heavy Reduce electrical load. Although you may elect to use any other method. The integrated circuit (UI) may be mounted in a socket if desired.emitting diodes (LED's). place a block of wood over the printed circuit board on a tabletop. leaving the used piece under the block. Snap off the excess piece. 13. 14. It would be a good idea to jump ahead a bit and install the IO LED's as shown in Fig. with a fine sandpaper resting rough -side up on the workbench.circuit board is recommended. Position the cut or break line of either end of the board. 2.Tff . Ili!! is 1111111f I holes. the entire chassis for the Battery/Alternator Monitor can be constructed. Fig. Solder LED 11 JUMPERS is used like a glue to MAIN BOARD fix the copper surfaces together so that the boards are secured.circuit board is cut with a small saw into two pieces. which can be placed at almost any convenient location on the dash panel of your auto. 12. gouge a deep score line where the cuts are to be made. You may want to add some epoxy to make the joint firmer.7 On 9 Yel. which also contains the single row of Fig. 13.0 3 Yel. The cuts can be made by a Dremel jigsaw.Batt rails from both boards are SOLDER BEAD AT FOIL SIDE REAR + BATT soldered together so EDGE RAILS that they require no electrical interconnection. Otherwise. the two boards will be held in rigid positions. As shown in Fig. 14.8 On 7 Grn. the one to be described lends itself to a rather compact package. 5.TTt . You may want to refer to the schematic diagram shown in Fig. By using Global Specialties Corporation (GSC) EXP. author's working model. but it may not be necessary. It is . the printed. The cathode for the LED is the lead closest to the flat surface on the body of the LED. 13. 2. place the smaller one (LED board) flat on the workbench with the foil side facing upward. The smaller piece (the LED board) is used to mount the ten light.Ttfft ¡¡ 1f tttttlttllllttlltlttttltttltittttttttl 10 16 I0 Lt2D BOARD30 26 1. the edge of the wood block.3 On 8 Grn.TABLE 1 INDICATIONS AND REMEDIES 1 Color Red Indication Meaning (+ DC) Engine Status 11. the scored line is not deep enough. 3 and Fig 4. . the boards should be attached to each other as shown in Fig. As shown in Fig. Then.4 On 6 Grn. The prototype shown was designed to fit into a standard protective box used to store cassette tapes. Solder only the cathodes for each LED. the LED leads will pass through the holes and be directly under the foil side of the main board. First. The larger of the two will form the main board.1 On No problems Normal Operating Range Daytime operation No problems No problems System should be checked High charging voltage big p Next. 2 -This cross TOP EDGE sectional drawing LED BOARD FLAT details how the two SURFACE boards are attached to each other. which is accomplished as outlined in Fig.300 -PC circuit board material. Both + Rails on the boards should be next to each other so that solder will bridge the boards and secure them together. 15. and the table edge.5 drain 4 Gm. Repeat the procedure until the two boards are obtained. Now. If you have trouble. 50 imm 10 41 soldering action connects the two + Batt rails together so that a jumper is not needed.Diagrammed details on how to cut the main and LED boards from a Global Specialties EXP -300 PC experimenter's circuit board. That IÍIIIIÏIIIIÎ tT ¡¡}}tt }}TTtttt}}ttttrr}}}}tt}}MAIN }}BOARD }}}}ttrrrrff}}}}}}}}}}tt}}}}tt tf11T flf1}ttff ?fffffff . By placing a few spots of solder on the foils of each board (where they meet each other). Numbers at the bottom are for jumpers that connect to the LED circuit board. LED 10 Ì RED TO BATTERY LED 10 LE D 1 RED ii /J=== 1vrj YEL GRN GRN GRN P ifif GRN GRN YEL RED =rt ìr'=fi= fr LINE 18 17 16 15 14 13 2 11 13 U1 PIN 11 011 -137\13-0}-0 + BATT RAIL 3 DOT DISPLAY U1 9 DOT /BAR DRIVER LM3914 F1 1/2 A external common -ground connections in the circuit.. 10 8 9 7 JUMPERS cz z 6 5 3 Ut + 1 BATT RAIL -10 Fig. How It Works A quick glance agram in Fig. .p. 5) is a ten -turn trimmer type and does assist in accurately adjusting the voltage steps to those shown in Table 1. with a positive ground vehicle. The jumpers shown from pins 9. Note the battery connections along the rear of the board. from the leftmost red lamp to the present reading..profile socket be used. along the front edge of the board there are numbers (1 to 10) shown. The unit will illuminate one lamp (LED) for each voltage condition en- countered in the charging system. The latter is referred to as a bar-graph display.. as long as the plus lead went to the positive side. Otherwise. The numbers on that board refer to row A of the main board at the holes as shown.. 3.. When the operator sees only green (or an occasional yellow) light on the panel.. especially if you are going to mount the Battery/Alternator Monitor in the cassette box as the author did. it seems that the single lamp dot display is the most logical to use.. 4. In fact.itt JO LED 1- tttt T leads were connected in reverse. it is advisable to use the same insulated wire for all jumpers.. It is achieved by wiring pin 9 (mode control) to pin 11 on U1.. the monitor will work because there are no Of course.circuit chip and a bunch of light. 5 at the schematic dibe all that is neces- will . There is another side benefit of using only one lamp at a time-current drain is lowered and. Numbers through 10 correspond to LED1 through LED10. the potentiometer chosen for RI (see Fig. Fig. or if the 36 Fig. By connecting pin 9 to pin 3 on UI. especially those spanning more than two or three holes. Using Fig. and 13 through 18 of UI are soldered into their respective holes and placed over the top of the board..* . However. or used. will be illuminated up to the maximum voltage on the line at that moment. + Those may be made by circuit pins or directly to the foil. whenever a red LED lights. 2 4 TTii . suggested that a low. 10. the bar-graph mode will be enabled. in the circuit.. 2 as a wiring diagram. therefore.... While not entirely required. . That is called a dot -graph display. F1. Since a red lamp showing on the instrument panel will signal trouble to most people.emitting diodes which is actually the case. it will attract the driver's attention immediately. . 1 JUMPERS 4 3 2 1 5 6 10 9 8 * A ¡of 115 t i i t t # ttt.. Short circuits in an automobile can draw currents up to 200 ampere that result in melted cables and the high probability of fire. Be sure to include the protect fuse. A mistake here will cause an LED to come on out of order. but be careful when you connect the jumpers between the two boards. Also. Those are the connections that will be extended by insulated jumper wires to the respective numbered connection on the LED board. the temperature rise of U1 is greatly reduced. Dot or Bar BATT RAIL TO 12V CAR adjusted.BATT - l BATT + REAR EDGE 11'üiiii " :. 1 NillÑpM. install the jumpers and other parts in the locations as shown. R2 01 . The diode designated DII was added mainly for safety's sake to prevent damage should the unit be installed. numbers l through 10 are from the left to right. it has remained untouched since the monitor was placed into regular service. The latter is outlined in detail in Fig. 4 -The wiring diagram for the LED board is simple. Once R1 was U1 PIN 3 x012 10V R1 500K 7 2 4 BAR DISPLAY 8 tR1 1K 5-The entire circuit for the Battery Alternator Monitor appears to be one integrated. in either event. Thin insulated wire may be used for that purpose.Wiring diagram for the main board. he or she will realize everything is functioning normally. It is possible to wire the monitor so that each lamp. it may cassette protective case. red (6th) lamp should be on when the DVM is indicating approxD3. Most of the circuitry is contained on board the LM3914 dot/bargraph driver integrated. you will be in a monitor on or off because the power consumed is so small better position to analyze the electrical system and to be able that it will never be noticed. espanel. display is provided. - D12 BATT- MAIN BOARD R1 Adjustment Once the circuitry has been cornpleted . Since it would be difficult to see the holes in the black assist you to temporarily connect pin 9 panel against a black background of the case's inside surface.5 or 12. Prepare the box by drilling ten small holes in the 1.8 volts. or have someone start the car at least once a week. 10 -volt. try a different Zener diode D12 -Zener diode. The lower value in the Parts List is for a bright readout. glue or epoxy. green 011. 010. adjust the variable supply to PARTS LIST FOR BATTERY /ALTERNATOR the voltages indicated on Table I and then check the display to MONITOR be sure that the lamps light as shown. when you get into it in the morning it should still be hood. 09. solder.Plastic cassette protective case Plus: Wire.sary to see the simplicity of the circuitry. you will tiometer find that the chassis you just constructed will fit quite nicely R2-1000. 1 -A. that the voltage has dropped below the 12.circuit chip plastic box. connect the leads to a source of LED BOARD variable DC voltage and set the voltage LED for about 13 volts. The spacing is chosen to match that board of the spacing of the LED's. which further eliminates several resistors. the unit. we highlighted to pin 11 of the UI so that a dot -graph them for easy viewing. Without the fuse.6 volts.2000 -ohm. 1/2 -watt.Light. be sure to insert a 1/2-ampere fuse as close Look in the car window (in the AM) and the lamp shows to the tie point as possible.emitting diode. you are inviting yellow.6 volt level. If not. When you have determined that the unit is working. However. or to a plug that can be inserted into the cigar lighter. the sixth 01. That placement hold the unit to the underside of the indicating about 12. For that adjustment. some to understand your automobile's battery and charging sysvehicles have a sort of hood over the instruments that shades tem. A digital voltmeter will assist you in the adjustment. you may want to disconnect from home. If you have been careful.emitting diode. adjust RI until one or more of the lamps Here's a view of the Battery/Alternator Monitor just prior to assembly in its plastic illuminate.circuit narrow edge of the box. 10 -turn. Another nice feature is that one resistor (R2) acts as the current limiter for all the LED's. 04 -08. Once There is no need to provide a switch to turn the battery you watch the activities for a couple of days. if you take long trips to predict future troubles before they leave you stalled far and leave your vehicle behind. If no lights are on. The same for the diameter of the 1. or better In the event the linearity is poor. Open the door and notice that the red lamp indicates disaster. the LED's will fit nicely The glow of the little lamp on the dashboard of your through the holes and the chassis will remain in place with automobile may have a certain deterring effect upon a potenlittle or no other fastening devices. Resistor R2 may be varied for LED brightness. linear -taper trimmer potenWhen you are ready for packaging the monitor. fixed resistor (see text) into the front portion of a standard audio cassette protective U1. made directly to the fuse block. you may be makes the unit visible whenever one glances at the instrument expected to replace your battery within six months. 1 - -' 52 .Light. tial thief because he would have no way of knowing whether Installation or not the lamp indicated an armed alarm system.Light. Begin your automobile is left to your imagination. holes. D2. R1500. or whatever. voltage on the line. etc. However you do it. the higher value offers a dimmer light.000 -ohm. other hot connection under One more thing you will learn is just how a load affects the the dash.Continental Specialties EXP-300 PC printed. 1 -watt (1N1744 or equiv(D12) as they do vary somewhat. illuminating one lamp at a time. it also contains a stable reference supply and the drivers for the LED's. 50 -VDC.Silicon rectifying diode. However. A couple of pieces of two -sided tape will night. Mounting the Battery/Alternator Monitor on the panel of Build this simple but useful piece of equipment now.emitting diode. because that will be governed by your choice of LED's. If everything is right. yellow imately 13.circuit chip. The key thing to remember is that if you park your car at them from sunlight. Connection to the auto's electrical system may be pecially if you live in one of the cold climates of the country. In addition to the comparator circuitry within the package. as several other 10the Parts List found to did F1 -A fuse with in -line holder volt units checked.LM3914 dot /bar driver integrated. The Zener diode specified in alent) was work well. 1) consisting of switches SI through S20. Feel free to customize the Infrared R/C Transmitter to your own liking. 13 commands are implemented from the previous group. For example. channel-step. there are up to 32 commands such as on/off. That oscillator's output is then divided by 13 or 12 to form frequencies of 35.INFRARED RIC TRANSMITTER Build your own Remote /Control device and save bucks on cable -TV converter rentals! By Edward Asbell Payne The circuit described in this article will transmit either Motorola or the modified Motorola/OAK format by simply moving a jumper on the printed. fine tune. R2+ several commands generate a continuous R3+ R5 R3 + R5 train of data for functions such as volume 12 14 R1 R2 R3 R4 R5 R2+ R5 Cl 0 2 4 6 8 10 C2 1 3 5 7 9 11 13 15 up. For each key (switch) closure. TABLE 1. A transmitted zero consists of 256 pulses of 35. among them are General Instruments. In the circuit described in Fig. simply experiment with row and column closures until all commands have been identified. respectively. I have found that the implementing only the on/ off and recall functions on my home unit suffices me quite well. thanks to the ease of implementation and the low cost of today's MSI /LSI integrated circuits. however.0 kHz followed by 256 pulses of 37. recall. Ul. Tables and 2 are provided to aid the builder in selection of functions. is internally triggered by the MC14457 chip (U1) upon detection of any key closure. a free- C3 SPARE MUTE SPARE SPARE SPARE running ceramic resonator oscillator C4 SPARE FINE SPARE TUNING FINE TUNING TABLE VOL VOL SPARE 2 OFF SPARE SPARE SPARE MODIFIED MOTOROLA/OAK FORMAT R1 R2 R3 R4 R5 Cl 0 2 4 6 8 C2 1 3 5 7 9 C3 ENTER USOED USOED USED C4 NOT USED NOT USED NOT USED USED NOT RECALL ON'OFF (CRI). You may also reduce the number of functions and save some cost on the quantity of switches you need to purchase. it is used by one large supplier of cable -television channel converters with a slightly modified format.MOTOROLA FORMAT 1 How It Works The MC14457 integrated circuit. But what do you do when you subscribe to cable TV with a remote channel converter and your old remote control becomes next to useless? Do you lease a remote control. however. Each of those companies have their own data format and are not compatible with one another. some receiver manufacturers may mix the control lines at the receiver end. the way you use to lease your telephone. National Semiconductor. leading to departures from the tables. this project might be for you. or are you lured into a more expensive package of channels just to receive a remote control? Maybe you just want a construction project that is fun and will receive lots of use. Most closures generate a single burst of data for each key depression. Under the Motorola format. I. If that is the case. etc.92 kHz. etc. This article centers on the Motorola MC14457 CMOS remote /control transmitter chip. and on/off. volume. enter. operating at 455 kHz.0 kHz or 37. A transmitted one is the same process simply reversed in order. and Motorola. Those are 0 through 9.circuit board. They are becoming almost standard equipment for most television sets.92 kHz. There are several manufacturers of remote -control chip sets. Ul generates a unique burst or train of frequency -modulated bi -phase data. INFRARED REMOTE CONTROLS (R/C'S) HAVE BEEN AVAILable on many home -entertainment devices for several years now. encodes a keypad matrix (see Fig. The odds are that if you purchased a television receiver within the last several years you own a remote control. Aside from being designed for use in many TV sets and home entertainment devices. . Under the modified Motorola/ OAK format. If you fall into any of those categories. then wire your keypad accordingly. 92 -kHz bursts that are gated by a DC signal from pin 13 of U1. Components R1. however. That signal is then passed through two paralleled gates. See Fig. C2 and CRI (see Fig. U2-a acts as a simple inverter. That lowers the unit's cost and makes the selection of available switches broader. in effect shutting it down. First -rate (not grab -bag variety) transistors have low DC leakage.1. I). Cl. so that the battery life is almost equal to battery shelf -life. In the modified Motorola/OAK format. has its input hard -wired to a logic one (see Fig.0 kHz.8K 2 Q6 2N2222A C2 c 1ri1 Q 2N3904 r°4 Q2 S1 2N3904 Fig. and is set for approximately 60 mA in this design. That eliminates the need for a power switch and assumes essentially shelf life from the battery while the unit is not being operated.I 1N914 1000pF C3 C4 50 220 B1 9v i 1 Each key closure is encoded into a 5 -bit word preceded by a header of a zero and a one effect a 7 -bit word. a printed circuit board is recommended. Construction The circuit's layout for the Infrared R/C Transmitter is not critical and almost any method of construction will suffice. and is cheap insurance for a five -dollar integrated circuit. 1) form a resonant network..-04 519 Or . S2 O 03 2N3904 S7 »D4 4o 58 S4 S5 o of S9 S10 P. 2. passing both high and low frequencies from Ul's output on pin 15.ÿ o 514 512 S15 N3904 LOW FREQUENCY - pl 35. meeting the requirements of UI's internal oscillator driver. 1 for circuit action. 1). Capacitors C3 and C4 serve to bypass noise in the battery power supply (see Fig. Diode 54 LSB+3 MSB BURST D3 prevents possible damage from accidental battery reversals. R2.Schematic diagram for the Infrared R/C Transmitter includes the keypad matrix hookup. Those are wired as inverters to restore the original polarity of the data and to provide more than adequate drive for the Darlington arranged LED drivers.P4 S20 KEYPAD DATA SIGNAL U1 PIN 15 BURST ZERO ONE START START LS8 LSB+1 LSB+2 DATA MODULATION U1 PIN 13 jumper in the MOT (Motorola) position. CMOS integrated circuits were used throughout. Since CMOS only consumes power while switching. 1) when the LED'S are active. With the R1 -in 10MEG 11 M 1 3 CR1 R2 SEE 455 KHz 68012 12 FIG 2 1/4 4011 LOUT OUT 2 NO CONNECTION 2 LED 15 1 XC880A 14 1 16 1 111 MOD 1/44011 1 R3 5612 uz 9 13 OAK 12 MOT 13 1/44011 1/4 4011 TRANSMITTER MC14457 10 11 LED2 / XC880A Q5 9 10 R4 C4 R5 C3 7 R4 2N3904 6. the low-frequency portions of the word are removed entirely. U2 -b and U2 -c. 2 -The frequency bursts you can expect when transmitting the number 9. The remaining unused gate. The Motorola system uses 35. Fig. that prevents any noise from being coupled into U2 -d and consuming battery power. that 7 -bit word is again preceded and ended by a low-frequency burst of 35.0 -kHz and 37. U2 -a AND'S in the modulation signal with the data stream to remove the low. Resistor R3 limits the current through DI and D2. The OAK system uses only 37. That makes the modified format unique and prevents interaction or use by other controls in consumer appliances which chose the Motorola chip for the foundation of their remote control design. Q5 and Q6. One may be copied from the . for ease of construction and small size. D1 I C2 C 100pF 1 . U2 -d.92 -kHz bursts as seen from pin 15 of U1. Transistors Q1 through Q4 serve to eliminate the necessity of using double -pole switches by effectively grounding both row and column inputs on UI with a single -pole switch.92 kHz 517 '4 S18 . and all bipolar transistors are in their quiescent off state when no keys are depressed.frequency data for the modified format.0 kHz (MISSING ON MODIFIED FORMAT) HIGH FREQUENCY - 616 37. Refer to the schematic diagram in Fig. In addition. In the OAK jumper position (see Fig. 2N2222 NPN silicon transistor U1. almost any tint of plexiglass or plastic will do.circuit chip(Radio Shack 276 -2411 or equivalent) CAPACITORS C1. 4 -watt.Fig. 55 . the printed circuit board looks the same. Surprisingly. and hardware. which have suspended particles to achieve their effect.emitting diode (Radio Shack 276 -143 or equivalent) O1. ?r ROW 4- Here's an x -ray view of the printed.Motorola MC14457 integrated. Fig. 16 -WVDC electrolytic capacitor electrolytic capacitor RESISTORS R1-1. 5 °0 resistor ' ADDITIONAL PARTS AND MATERIALS B1 -volt DC alkaline transistor radio battery S1 -S20 -Any SPST.circuit board with the components positioned in It doesn't matter how many pushbuttons you will use on your transmitter.emitting diodes. normally -open. Any infrared LED with energy centered near 880 nanometers will do. or an etched and drilled circuit board may be ordered from the source given in the Parts List. battery holder.Megohm. You will be able to see them blink in a dark room. Do avoid smoked plastics. 3-Same -size foil layout for the printed. 50 -WVDC ceramic disc capacitor 50 -WVDC ceramic disc capacitor C2. 4 offers an x-ray view of the foil on the reverse side of the printed. 3. LEDI and LED2. 35 -WVDC C4. but a metal box is highly recommended in dry climates where static discharge could bridge through a switch and consequently into the CMOS circuitry.circuit chip U2-CD4011 or MC14011 integrated. momentary -co. IC sockets. 5 R4. tact switch Battery connector clip. Most translucent colors have little attenuation at infrared wavelengths of light.1000 -pF. The Infrared R/C Transmitter may be housed in any suitable enclosure. Many substitutions are possible.circuit board.circuit board with the foil side down and the locations of components indicated. may be mounted with standard plastic grommets or may be housed behind a protective and decorative lens. Parts were chosen with availability and cost in mind. LED2 -XC -880 -A infrared light. The LED's issue a light spectrum that includes the visible red frequencies.6800 -ohm. Fig. e -9 closure. wire.220 -uF. '4-watt. 500 resistor resistor R3-56 -ohm.100 -pF. solder.50 -uF. '4-watt.2N3904 NPN silicon transistor 06. '4-watt. 03. place. The infrared light.05. but also note that some (Continued on page 99) PARTS LIST FOR THE INFRARED R C TRANSMITTER SEMICONDUCTORS CR1. 5 °0 resistor R2-680 -ohm. 1 2 4 3 COLUMN B1 foil layout given in Fig. Those will attenuate light at any wavelength.455 -kHz ceramic resonator (Radio Shack 272 -1303 or equivalent) D1-1N914 silicon diode LED1. where the path of darkness rule does not apply.M. rather than something supposedly designed just for foreign listeners. Be prepared to lose some sleep for some of the more difficult Pacific SW loggings.395 kHz at about the same time. But on the other side of the International Date Line. Though the tropical night envelopes you. New Zealand is exactly a half-a -day away from UTC (Universal Time Coordinate. But.160 kHz at 0330 UTC: 15. or Canada you live. Radio New Zealand was able to stay on SW. but then an economic crunch hit the station. Many SWL's consider that to have been a plus. spans the distance from UTC + 8 to UTC +10 hours. Or. lower-SW frequency stations. overhead there are the twinkling points of the Southern Cross. and still others are real toughies that take real tun- ing skill. Some of those stations are easy to hear. from somewhere in the darkness beyond the flickering light of the torches. local time. Icontinued on page 102) Radio Veritas offers a handsome multicolored OSL card. "half a day away. On the lower SW frequencies. beginning with the largest of the Pacific nations. Australia -Radio Australia is one of the world's major international broadcasters.995 kHz at 1130 UTC. just two time zones to the east in the Cook Islands.midnight and dawn. Radio New Zealand had a separate SW programming service. The old phrase. the Australian Broadcasting Corporation also airs domestic SW programs for the home folks who live in the more remote areas of the country.M. at a more reasonable hour in North America. luck. but the separate programming for overseas listeners was replaced with relays of domestic medium -wave programs. reasonably good listening equipment and. continent by continent. But with most of the lower-powered. we'll continue the journey. we've begun working our way around the globe by SW beginning with Europe and Asia.705 kHz around 0030 UTC. Look for Radio New Zealand on 9. we'll find a mixed bag of DX targets. Some of the major Pacific area broadcasters use frequencies above 10 MHz. 15. because of its large size. and I agree! I much prefer to hear the same programming as New Zealanders do on their own AM radios. One of those home service stations which can be received in North America is VLM4. when it is 6 in the morning (0600) UTC.035 kHz at 2130 UTC.920 kHz. a term which is replacing the old standard. to receive a signal.M. Here are a few times and frequencies to try: 5.S. In the future. rather than a loss.M. the corresponding local time on the Pacific island of New Caledonia (UTC + 11) is 0100 (1 A. That is depending on where in the U. In our last few columns.) Monday! And Australia. others provide a bit more of a challenge to tune in. . In addition to the broadcasts of Australia's overseas broadcasting operation. Chances are that it's not too different from yours. When it is 1400 UTC (2 P. SWL's in North America will have no trouble tuning in that station at various times of the day. at the very same moment. (1800) for the Zed' ers Down Under. Somewhere across the lagoon. You are standing on the beach.720 kHz at 0500 UTC. this time finds our SWL'ing survey all at sea. you know the surf is rolling whitely over the coral reef. As has been the case with our previous continental looks at SWL'ing. and 21. Greenwich Mean Time or GMT). But that day may be today or tomorrow. the local time is 0300 (3 A. New Zealand few years ago.) Tuesday." is literally true when you are talking about the lands of the Pacific. Because of those day-dream visions of the lands surrounding and dotting the Pacific. since the International Date Line runs right down through the mid -Pacific. In New Zealand. Fortunately. Now let's take a closer look at those DX targets. yes. broadcasting from Brisbane on 4. a "path of darkness" between broadcaster and receiver must exist.620 kHz signing on at 0930 UTC with its bellbird interval signal and the start of National Service programming. That is the Pacific at least my mental image of a South Sea paradise.) on Monday afternoon. checking out the stations you can hear from the -or great expanse of the western ocean. There are few DX'ers who don't get a special thrill from tuning the SW broadcasters of that exotic part of the world. Give that one a try between about 0900 and 1300 UTC. 9. try 17. it is 6 P. 6. -A Philippines -Here there are several stations for SW listeners to tune.580 kHz at 1400 UTC or 2100 UTC. between post. it is an area of great interest to SW listeners. and surely one of the most important SW voices from the Pacific. comes a pulse -pounding throb of drums. the local time is UTC + 12 hours.By Don Jensen V ON DXING Pulling in the nations that share the Pacific's warmth! DON A WARM AND SCENTED BREEZE. the best times for reception in North America are around 0800 to 1500 UTC. 4riOMMIR - I NT AOC FAST NS p:.r oLd gat:nn -IwuG EI. n AGC switch.1 y .UNCTION CLOCR}`O.. um= IS 1 .1.. The program mable band scan feature permits scanning over operator selected - 'thium battery memory backup Estimated 5 year life) is built -in. with an optional CK-1 DC cable kit. and its ten memories allow moving from band to band without concern for mode of operation.. commercial.11)N 4141.8 VDC. on 13. A noise blank Ind an all -mode squelch circuit Wrther enhance the cperators ntrol of his listening environment. WI dual digital VFO's. The R -2C00 places the world our finger tips.011 ammo Iipmw . band and mode information. ten memories that store frequency.ICCI ir S.CJ®f.. With the sensitive R -2000. The R -2000 receives in the LSB. It Ias three built -in IF filters... and dual 24 -hour clock with timer.i Scan the World.EOLK .00 receiver has opered the coors to a new world the 150 -kHz to 30 -MHz HF bands." a carrying handle.14ii1.11111MION ORIMIPM.. high and low tlpedance antenna terminals.. 06. . knits.`-MEMORY I FE_FVan UT . 1Ol ® MOOG MEN lm -Illm PC. Ind an optional 500 -Hz narrow fl ter is available. An optional VC -10 VHF converter for 118 to 174 -MHz. an "S" meter. allows access to police. programmable band scan. 2 s ---. California 90220. and an RF attenufor switch allow selection of th Zest signal -to -noise ratio. fluorescent tub digital display. and FM modes. I = _ \JJ " - ININNUIMMO111. 1-2000 optional accessories: converter HS -4.maximum flexibility and to enhance the excitement of listening to staiion from east to west.wmm 4pwim emeirl amp immo gum= igoom ummso ilmilmt MI- AF GAIN _ \ « « t 0.11.ff gm= anwor] ap. and iperates on 100/120/220/240 VAC.S and prL'eI PJWER uu llllllf- T MEA MIS INN= . aviation.1.1. with JARROW /WIDE selector switch. a tone ontrol.. and from poe to pole. and :wo meter Arrteu frequencies. 1. Other features dude a record output jack.. OMEN. AM. 1111 West Walnut Streer. marine.1 . headphone jack. CW. an Udible "beeper. Comptor. with microprocessor controlled oper_' ating features and an UP conversion PLL circuit fo.. tr is outstanding radio has the versatility needed t reach out and cat_:h those distant and elusive statiors in the mo remote areas of the world. . onl he best in selectivity will do. NSNAEI W Ir Uft r-r 1r: .w TIMIP MI.©. memory scar. reducing scan cycle time.:5 = NM OIIA11 Ge -3 `1- SQUELCH . ' TIME .iiMiiiii1.rications. HS nd HS -6 headphones DCK -1 CC 'C -10 VHF YG -455C fable kit 500 -Hz CW fitte (i'eC ILSa:n)I. -600 kHz 'IF filters tanker RF 1A'_ Ñlore information or these products s available from autt'orized dea+ers f Trio -Kenwocd Comm. ilemory scan allows the operator to ican all or only specific memories.c NA . 'enwoöd's . SCAN MEN TONE _ . and an external.1. It has urge. peaker :ack. front mounted speaker. L v L J D) D YOU EARN $20 FOR EACH TIP L __) IL Is There a Ground? I often have to power-ground electronic equipment in older buildings having the old fashioned two -wire outlets. because there's usually not enough room Steel -Wool Cleans I have boxes and boxes of components collected over a period of years. the tip of my finger is all that is needed. I push the wire into the steel wool with a fingertip. (Color photos lose too much contrast.E. and all entries become the property of Hands -on Electronics. Turning the nail tightens the post rather than the mounting nut. to fit a socket wrench inside the cabinets used for my home -brew projects. I temporarily secure the screw to the screwdriver with a drop of plumber's grease. R. New York. Because the outlets lack a ground pole I take the earth ground via an adapter from the screw that secures the outlet's cover plate. I can now quickly check whether the plate is grounded. Schaumberg. but clever. T. you will receive a check for $20. If the plate is grounded the tester's ground lamp turns on. Other times. a project. or testing. NY 58 . So.S. Instead of the time. or I sometimes use my long nose pliers. If the oxidation is really stubborn. 200 Park Avenue South. P. Room 1101. Send all mail to Hands - on Electronics Testbench Tips.Q. G. we will be unable to return your tip or photo. I replaced the tester's "ground pole" with a short wire tipped with test probe which I press against the plate. idea that helps you build a better project. but not enough to damage the device. let alone a screw that's even too small for a "hold -e -zee" screw- printed circuit board which I keep on the workbench. let us know about it..and -white photo of the idea in action and send it to the Editor.and 20 -pin DIP's. which is so thick and clingy it can even hold a #10 screw to the screwdriver. Sorry.. IL The very next time you come up with a simple. Pick up the grease at a hardware store that specializes in plumbing supplies. FL He's All Thumbs My large fingers can barely hold a miniature screwdriver. Woodbridge.) If your tip is used in this column. applies more than enough pressure to keep the integrated circuit from flying out. R. TX but it often turns out that the plate isn't grounded to earth.-Denrer. Time has oxidized the wires so that soldering is difficult.U. Now I tighten the assembly by using a finishing nail passed through the hole in the post. Miami. which driver. Put your idea on paper (typewrite it).. By modifying a standard outlet -tester so the earth ground is tested manually. New York 10003. Novel Bug Holder I use an ordinary "Yankee" film clip to hold an integrated circuit when I need to straighten bent terminals. spelling out the details on one sheet. CO New Way for 5 -Way It used to be difficult for me to tighten the mounting nut of a 5 -way binding post. Take a black. I glue a small bit of coarse steel wool to a small scrap of is exactly the right size for 16. Passing a wire over the steel wool removes the oxidation and leaves the wire clean and ready for solder.K. The clip. I hold the nut with a small open -end wrench from and ignition tool set. Waco.consuming process of scraping the oxidation off a wire with a knife. or do a better job of installing. . Some American. Obviously.vintage types that can be substituted are (number cf pins in base and filament voltage given): 11(4pin. Again. 37 (5 -pin. Main Features The circuit is of the regenerative. 26 (4 -pin.3. Many readers who built the Unidyne one -valve (vacuum tube) receiver also expressed interest in the possibility of an all -band receiver with plug-in coils. 30 (4-pin. they perform well in this circuit at frequencies up to more than 20 MHz. The regeneration arrange- 'Original project appeared in Electronic. 6. in the Fall 1984 issue of Hands -on Electronics. and appears here by permission 59 .5volt). there is a real interest in experimenting with early circuit designs and tech- niques. Bring back the excitement of the "good old days!" DJUDGING BY THE RESPONSE OF OUR READERS TO THE article "How To Build a 1920's Style Wireless Receiver". 27 and 27S (5 -pin.try construction will have enough information to assemble his very own receiver. So by popular demand we present the Reinartz 2. but sufficient stocks are available provided you can find them at flea markets and old radio repair shops. the serious buff may prefer the kit so that he would achieve a receiver that is very nearly a replica of what would have been assembled in the 1920's. Australia. 1984 edition. 1. However.3. and were made at the beginning of WWII) are now as scarce as hens' teeth. and 76 (5pin. Its 1930's triode vacuum -tubes and plug -in spiderweb coils. The Parts List provides the address of an overseas supplier.0. The receiver was designed around two medium-impedance triode vacuum tubes. Those vacuum tubes have 2 -volt filaments and a 4 -pin base.5.volt). within this article we have supplied sufficient information so that the hobbyist active in RF circu.EWLE AN ANTIQUE EORT WAVE RAEO By David Whitby Tune the airwaves with this vintage shortwave receiver. 2.volt). August.volt).detector type followed by one stage of Lidio amplification.volts).volt). 2.1. The receiver described in this article is based on a kit prepared by an Australian supplier. 6. type HL2K (RAF type VT50). built to the same vintage standards as the Unidyne receiver. 1. vacuum-tubes of that era (they are a 1920's design. The tuning and reaction controls. that last step reduces the amount of travel required by the reaction capacitor over each tuning range. a suitable receiver of high -quality 3400 -ohm . which has a cove routed edge to create a really attractive vintage appearance.impedance phones supplied with that kit. and the terminals for the antenna.L1. also of black bakelite. and consists of a 25 -pF. about which more will be said later. which is driven by a precision 6:1 vernier dial (used in kit). The 200-pF section is used for tuning the receiver: the other section is connected via a 30 -pF trimmer capacitor (C8) to the reaction capacitor (see Fig. on /off switch and phone jack socket are mounted on a front panel of gold -lettered black bakelite. Although not a feature of the original Reinartz circuit. A rear sub -panel. ground. 3).circuit transformer (ratio not particularly critical) should be used for best results. The plug -in formers for those coils have been specially produced by the parts supplier (see Parts List) and allow for easy winding of coils that are very efficient. beehive capacitor fitted 60 with a shaft and mounted in a brass frame. Plug -in spiderweb coils are used to cover the various bands (broadcast to approximately 20 MHz). In terms of appearance. which is attached to the baseboard by means of three small right -angle brackets. air-spaced. Both the capacitor and the dial are of relatively modern design but make for precise and stable tuning on the shortwave bands. and power -supply connections. the receiver is built on a high quality (Meranti) wooden baseboard. even though they were first designed around 70 years ago. Tuning is carried out by an air -spaced variable capacitor. The reaction capacitor has been built especially for the kit. in effect. The tuning capacitor has two sections of 200 pF and 90 pF. they do not detract noticeably from the vintage flávor of the radio. L2 C2 CR C3 ON /OFF SWITCH HEADPHONE JACK Since the Reinartz shortwave receiver is not in a cabinet. The receiver is designed to operate medium. and out at the PHONES jack (right). Parts location is an indication of signal flow -from the antenna coil (left) through V1.or high impedance headphones. That little capacitor has the advantage of requiring four turns of the shaft from minimum to maximum capacity which. For those who require headphones. viewers of the your project will be able to see your handiwork. holds most of the other components. then a small vacuum -tube plate. There is room to fit the transformer on the baseboard behind the front panel. As can be seen from the photographs. V2. gives a vernier action to the reaction control. ment is the famous Reinartz circuit. including the coil and tube sockets. If you have built the Unidyne receiver and would like to use the low. and other methods which used a fixed -reaction coil coupled to the tuning coil and controlled the amount of reaction by varying the filament or anode voltages of the vacuum -tube STC phones is available (1940 vintage).detector arrangements. Of those the Reinartz circuit was undoubtedly the best known. Two heavy -duty alkaline D -cells will provide a suitable supply for the filaments. the all -band type or two -tube receivers \ i . A battery box to hold those could be easily made up and the battery snaps for the 9 -volt batteries and holders for the D cells are cheap and easy to obtain.0 -4. and a B.detector type. or thereabouts.capacitor control of the regeneration (or reaction). the tuned -anode Variometer circuit (due to Armstrong).Parts location on the sub -panel and front panel. Previous methods of regeneration control included the swinging reaction coil (as in the Unidyne receiver). It used a spiderweb coil with switched taps to cover various bands and featured variable. Reinartz and was published in the June 1921 and the March 1922 issues of QST7 magazine.I.battery with a voltage of 90 volts DC. The coils from left to right correspond to the data for coils 1 through 4. The Reinartz Circuit Of all the receivers built by hobbyists over the years from the 1920's onward.1 a 'Ç Examine the windings on the four spiderweb coils. respectively. That single vacuum-tube receiver was of the grid -leak regenerative. It was that capacitive -reaction control which was the distinguishing feature of the Reinartz circuit. The more windings per coil. the lower the frequency range each will tune in. compared to previous regenerative. If you don't want to go to the trouble of making your own battery box. with plug -in coils were probably the most popular. The receiver requires an A. . 1 . L.battery voltage of 3. at approximately 1. while a series string of ten transistor-radio-type 9 -volt batteries will provide a long -lasting B battery. then a complete battery-holder system mounted on a wooden base to match the radio is available (see photograph and Parts List).5 mA. The basic circuit arrangement was devised by J. II . 61 .5 -volts DC at around 100 mA.'. in Table 1. 001 -pF mica capacitor C6-.. magnet wire for spiderweb coils (see Table 1).Megohm R2-50. phone jack. PARTS LIST FOR REINARTZ 2 SHORTWAVE RADIO i AC 9v Vol i e+ -. solder. RESISTORS R1.0. Optional AC power -supply audio -amplifier unit. knobs. -mH radio -frequency choke 3-UX4 4 -prong coil socket Base material. and other vintage radio parts.E ft46. right -angle brackets.$24. spiderweb coil A rarity these days.3 -30 -pF trimmer capacitor C2 -200. 338 Katoomba St. A full kit of parts for the Reinartz 2 is available from Technicraft. may be obtained by sending 2 International Reply Coupons (available at your local post office) to Technicraft Electronics at the above address. V2 -HL2K.impedance headphones (STC.covered solid. decals. reaction control became very tricky. I was soon modified to that 62 forms. and via surface air -lifted (2 -6 weeks). mainly due to the smooth reaction control made possible by the arrange ment -especially on the shorter wavelengths. etc. .00. sockets and plugs.(31/2-in. air capacitor (see text) C3 -(see text) C4. NSW 2780. VACUUM TUBES V1.S. If you wish.. The basic circuit shown in Fig.00 AC power-supply /audio -amplifier kit (requires 9-12 volt DC plug pack) -39. Simply explained. dia. dia.This vintage style A and B battery holder helps disguise the fact that modern batteries are used.00. The prices for the kit and other parts are: Basic kit (does not include headphones or power supply). on /off switch.Megohm ADDITIONAL PARTS AND MATERIALS L3 -2.impedance f Eadphones. Payments should be made by way of International Money Order or bank draft in $U.000-100. Australia.) $3. Adjustment of the capacitor provides precise control over the amount of positive feedback (regeneration) in the circuit.01 tubular paper capacitor .30 and (33/4-in..3. Packing and postage to the United States via surface mail (2 -4 months) is $14.5. the reaction capacitor is in series with the reaction coil and is thus able to control the RF current through that coil. $24. The Reinartz circuit quickly became popular.l-eOA4. Phone 011 -61-047 -82 -3418. Further information on Reinartz 2. but when it came to operation on the shorter bands. VT50 (see text) CAPACITORS Cl C8. C7.70. An unstable receiver was often the result. rubber. tapped spacers.. hardware. All of those methods were workable (some more so than others) on the long and medium wavelengths.$79.100 -pF mica capacitor C5.and 90 -pF. two.section.1.50 High. Katoomba. variable.copper wire (approximately #22 AWG)..000-ohm R3.) $3.00 Spare plug -in coil formers. 3400. a working pair of hi.50 Vintage -style A and B Battery Holder. 1940 manufacture) -$17.50 Spare tube -type HL2K (one per kit order) -$10. you can draw power from a hidden power supply and only the cable will be seen. It will be noted that the vacuum -tube filaments are connected in series. The lower coil is tapped to match the antenna load. which feeds back some of the RF energy amplified by VI into LI in such a way as to aid the original signal and bring about a great increase in gain and selectivity.yourselfer. plywood panel died black can be used here for the do. An V8-in.001 50-100K ¡ Sy ON/ Fig.5mH Cl 3 30p V1 C4 LH2K I 100pF 1 -The original Reinartz regenerative feedback circuit. That is done to provide an effective negative grid bias voltage for tube V2-obtained by virtue of the fact that both sides of V2's filament are positive with respect to the grid. together with C4 and RI. the main improvement being a reduction in body. Capacitor C7 is a RF-bypass capacitor across the B supply and SI switches power to the receiver by making or breaking the filament supply.) To improve the sensitivity of the detector to weak signals.L 2. Fig. Fig. 2 -The modified Reinartz circuit placed the capacitor ground level. C7 001 GROUND Q(A -.it. It comes routed and drilled.REACTION RFC ANTENNA HIGH IMPEDANCE HEADPHONES C8 3 30p -cn) L3 . shown in Fig. forms a grid -leak detector arrangement. the op- The first thing to do is to finish the wooden base. The circuit without the upper coil and reaction capacitor was suitable for receiving AM signals when the antenna was a few miles away from the transmitter in the early days! C5 R2 . (For a full explanation of that. 4. The setting of C3 controls the amount of regeneration. which drives the headphones. The Reinartz 2 receiver embodies many of the features of the earlier receivers. which is easy to work with. With 2 -volts DC across the filament. B -) 'SEE TEXT REACTION A + 3-4V UX4 COIL SOCKET (TOP VIEW) RFC 8+90V 3 -Here is the schematic diagram of the Reinartz shortwave receiver you can build. 3. Circuit Details Construction The full -circuit diagram is shown in Fig. Put that aside and then fit all the major mechanical parts to the sub -panel as shown in Fig. The various electronics components can then be soldered in position and the wiring run. L3 also operates in conjunction with bypass capacitor C5 to prevent RF currents from passing to the output stage. providing the DC grid biasing for the vacuum tube without need for a "C" battery. should you obtain the kit. The stator plates of the air capacitor provided electrostatic shielding so that the human body would not load down the regenerative circuit during the tuning process. at .and two -tube Reinartz receivers were described in the pages of electronics magazines over the years (Radio-Electronics had its share). or 3/16-in.capacity effects by grounding the moving plates of the reaction capacitor. Those frequencies selected by the tuned circuit are detected by the grid of VI which. timum setting being just short of the point of oscillation (as evidenced by a high -pitch howl). the average potential difference between the grid to heater element was 1 -volt DC. refer to the Fall 1984 article. You could make your own wooden base by using pine wood. the tuning and reaction capacitors and the on/off switch can be fitted to the front panel. Regeneration is accomplished by the L2 and C3 parallel combination. Check out decorative lamp stores for wire of that type. It was in that form that the circuit became widely known and used. using the black rubber-covered wire supplied with the kit. Many one. The coils L1 and L2 are wound on a spiderweb form and mounted on polarized 4 -prong plugs common in the 1920's era. An RF choke in that position was always a feature of the Reinartz receivers. so let's take a closer look at the circuit. Coil L3 is an RF choke that prevents loading of the regeneration system by the following audio -amplification stage. While the finish is drying. OFF > _J C2a'¡ L1 R3 R1 500K 1MEG 1MEG 4 r. Signals from the antenna are coupled via Cl (trimmer capacitor rated at 3 -30 pF) into the tuned circuit LI and C2a. which is at ground potential through R3. 2. Audio signals developed across VI load resistor R2 are coupled via C6 into the grid of V2. and requires only fine sanding and then two coats of satin polyurethane with a light sanding between coats. grid -leak resistor RI is connected to the positive side of VI filament. start with the photos and try to duplicate the receiver's physical appearance as much as possible. an outdoor long wire antenna of from 10 -35 feet. enabling loudspeaker pressed cardboard of plastic sheet may be used) cut to the output from both those vintage receivers. You may find it easier to make When the baseboard is thoroughly dry.7 -19. In most 2 C28 C2A TO REACTION cases any ground will be found advanP H TO TUNING TO TUNING CAPACITOR C3 tageous.A+ OUTPUT B +- GROUND ANTENNA C7 - COIL SOCKET H C1 TO PHONES L J as those below 550 kHz or above 20 MHz. the receiver performs right-angle brackets. the Unidyne receiver) and approximately 90 volts (for the Three plug-in coil formers (one large and two small) are Reinartz 2). proportions shown in the photographs. enables stations in that band. JACK o C8 o --- TOC f 1 1 1 1 64 . 60 turns into mesh. A rectifier/filter and IC regulator is used to supplied with the kit. pacitor. There are nine slots Most of the components are mounted on a printed. with brass terminals for all inputs and outputs. # 26 enamelled #36 DCC* Use 31/2-in.Reaction you want comes in as loudly as possiRange ble. After a little practice. mounted as high as possible.6 24 turns 14 turns Tuning coil wound first. C2. Also. designed for the receiver and also for the Unidyne receiver. 4. C3. now check the setting of the tuning ca1/4-in. former. which hold the front panel in place. quite respectable results can be achieved with a good indoor Sl antenna in many locations (10 -15 feet of wire around the room. Tune capacitor C2 so that the station Frequency L1. and as well as much larger receivers do without regeneration. control and speaker. 4 7. refer to the any band for the first time. because there are very few worthwhile receivers and. even if only weakly.creating that little item of radio history. mount the six 3/4 -inch tapped brass spacers by means of the An amazing number of stations can be received-esscrews from underneath the baseboard. pecially at night-on all bands with a good antenna and Both panels may now be fitted to the baseboard with the ground. Winding details for that band are the listening experience to be shared with others.6 volts. However. prepare the rear sub -panel to the approximate layout shown in the above diagram. along with a selection of wire of various provide a filament supply of 3. which is suitable for gauges suitable for winding all the coils listed. with correctly adjusted regeneration. included to make the chart complete. We hope you will get as much pleasure from building and operating the Reinartz 2 as we have from hunting down the Spare coil formers and wire are available for those who would like to experiment with that band or other bands. Table indicates the number of turns and wire gauges for of a voltage multiplier provides approximately 45 volts (for each band. it is interesting to note rubber feet into the four corner holes. 2 listed in Table is probably The unit is a worthwhile addition to both of those vintage the least important. That done. reaction capacitor plates fully out of mesh and vary the setting of the tuning TABLE 1 capacitor. fit the three that. Then gradually turn the reaction (MHz) Coil Comments Standard Wiré Gauge (SWG) capacitor.5-8. Pin l of LI goes to the 200 -pF section A few words about the AC power supply. and if you 21. which has been while the lead from C8 goes to the 90 -pF section. V2 BOTTOM VIEW When you are trying the receiver on Fig. both controls becomes more critical and 'Doubiecotton.560 -1. Optional more skill is required to obtain the best results. and careful tuning. etc). is also included. The volume of the station (Broadcast) #26 enamelled Use 33 -in. The spiderweb both receivers. the setting of are in these bands.covered. screws supplied and the wiring from the back panel to the components on the front panel completed. Make sure that AC Power Supply.Should you decide to make your Reinartz receiver from scratch.0 12 turns 7 turns Winding space and former #20 enamelled #26 DCC' same as Coil 2. you will find that it has shifted slightly. Antennas For best results. The band covered by coil No. You will probably hear some TUNING COIL WINDING DETAILS stations. An IC audio amplifier. together with a volume forms can be made from black electrical fish paper (any stiff. you will be able to tune the receiver very Most international accurately in a few seconds.5 40 turns Reaction coil wound first.5 -3. space between coils. as well as eliminating battery costs. In any case.0 5 turns 4 turns shortwave transmissions #20 enamelled #26 DCC' At higher frequencies. screw the four tuning a two -handed job.circuit (odd number) so that the wire will not touch except at the slot board and the whole circuit is housed in a black molded box crossovers.Tuning L2. so that the plates come . #32 DCC* will increase as you do that. Full winding instructions for the coils are supplied with the The power supply utilizes a 9 -volt AC plugpack and by means kit. 3 3. V1. such parts and re. is desir- able. Audio Unit you don't transpose the connections to the fixed plates of the tuning capacitor (C2). A guide sheet to suitable anH CAPACITOR CAPACITOR C2A G FIXED PLATES FIXED PLATES MOVING PLATES tennas and grounds is supplied with 4 each kit. former. four 8212 PIO (Parallel input/Output) devices. other computers.3 -1015D CART. who cared? Even today. A Look at the Circuit We'll start our look at the interface circuit at the output of the ZX81. Before we go any farther. by today's standards. 2. CI and CO. All the signals necessary for the communications interface are taken from the computer's card edge. The first two PIO's. While special connectors are available. But a few years back. With the interface's input capability you'll be able to monitor outside functions (such as temperature. you can really do a lot with you can even overcome one of its biggest disadvantages: the lack of a standard communications port. FIG. are used to control which of those four I/O ports are active. lines that are used by the port are buffered by Ul U3 (74LS244's). July and August 1983. We'll give you the details later. you can also make your own. which we'll call DI and DO. That allows for bosh audible and visual indicators which are excellent programmer's aids. humidity. light intensity. The control ports are used mainly to check and contro. 1 DO GND 01 GND D2 m 06 AO 05 Al D3 A2 D4 A3 INT A15 NMI A14 HALT A13 MREQ Al2 IORQ All RO A1O (CLOCK WR A9 BUSAK A8 WAIT A7 BUSRQ AS RESET AS M1 A4 RFSH 23A 23B ROMCS 65 . etc. we should mention that this interface can also be used with the ZX80 -the forerunner of the ZX8I. The RD and wR lines from the ZX81. add a polarizing key. the ZX81 is a great computer to learn from. That eliminates the strain on the drivers in ZX8I and is especially importar. and you're in business. We'll show you BOTTOM TOP how to use them shortly. Radio -Electronics. the CO port controls the UAR_ and the state of two LED's and a buzzer. Loxterkamp UNLESS YOU WERE HIDING IN A CLOSET THROUGHOUT THE entire microcomputer revolution. IA 1B 07 +5V RAMCS +9V SLOT SLOT -The port of the ZX81 computer. you should be at least somewhat familiar with the Sinclair ZX8I or Timex Sinclair 1000. are used for control input and control output respectively. acidity. We'll also show you how to use the interface along with the 8K batterybacked-up RAM board that was presented in our sister publication. modems. and at $100. are uses for data input and data output respectively. All the lines of the Z80 microprocessor are available at the card edge. I.t if other circuitry (such as a 16K RAM pack) makes use of those lines.1 -inch spacing). which is mapped into the last two addresses of the 8K -16K region of the ZX81.)with software. And if you have the patience.) via transducers. the status of data being transmitted or received. For example. That was the first packaged computer that sold for less than $100. The other two. relays and buzzers. the ZX81 can't do much. (Hereafter we'll refer to it only as the ZX81). Figure 2 is the schematic diagram for the interface. and more! We'll give you all the details you need to build the interface and we'll even show you how to control external devices (such as LED's. Cut the ends off a standard 25 50 connector (with 0. etc. along with L8-a and U8 -b. Granted. We'll show you how to add a standard communications interface to the ZX8I-an RS -232 serial communications it- port that will let you access standard printers.addresses 16382 and 16383. Control signals and data flow ire controlled by U10 U13.Add a RS232 PORT to your ZX81 By Edward W. They allow fcr easy interfacing between the ZXBI's data bus and the heart of the interface -an AY. Its pinout is shown in Fig. As you can see in Fig. A standard connector can't be used to get at them. DO Port Port ZX81 data line output pin input pin (transmitted data) 26 27 28 DO D1 D2 4 6 8 D3 D4 D5 10 15 17 29 30 31 D2 D3 D4 D5 D6 D7 19 32 33 D6 D7 input pin output pin data line (received data) 3 12 DO 5 7 11 D1 10 9 16 18 9 8 20 22 6 5 1 UART UART 7 ZX81 U11 U10 21 Setting up the UART The mainstay of the communications circuit is U14. an AY. and the number of stop bits are externally selectable-that helps make the interface compatible with other RS -232 serial communications ports.TABLE 1 -DATA PORT ASSIGNMENTS DI Perhaps the most important feature of control ports is that there are still three lines on the CO port and two lines on the CI port for your own applications and circuit expansions.3 -1015D UART or Universal Asynchronous Re- ceiver /Transmitter. Tables and 2 summarize how the ports are configured. RD 1/4 741S32 > 6 J2 4 (SEE TEXT) 13 i 12 +5V +5V 1/4 74LS32 16382 16 120 W > 1/4 J3 10 (SEE TEXT) 1/4 74LS32 74LS00 DO 13 A9 > Al > A2 A3 2 18 D 17 10 D 4 } > 003 24 DI U10 U7 16 15 1/4741S00 9 2 3 DO +5V 14 74LS139 D04 D05 8212 12 16383 5 1 A15 > A14 > 13 A13 > 8 Al2 > 11 6 81 +5V 12 D 161 9 U1D 10 D1 2 74LS244 +5V All> 14 D +5V (SEE TEXT) 13 120 14 17 D 24 U4 74LS139 DO U11 D 8212 D 12 M A10 > A9 > A8 > 18 D REO> D ROMCS 017 8 16 01 6 14 D +5V 1 12 16 Al> 11 D D RD 13 WR> 10 DO 14 15 RD> DO 13 DO U5 74LS139 RO WR 24 +5V U2. 74LS244 +5V D04 Cl r t20 005 U12 8212 12 D 13 DO eV M 0 0 0 0 0 o ó A6 > 2 A5 > 17 A4 18 A >- 16 v 6 13 13 16 ö ó óo ó ó 0 0 0 ó 0 ó 0 o US CO 10 +5V U3 WR 74LS244 13 R26 10011 RESET> U13 t 24 DI. D13 D14 8212 015 DI 15 12 1 1M DO OIZ 74LS139 8 11 018 i? 1 +5V 06 D07 DI7 DI 1.4 S9 RESET ZX81 DATA BUS 66 . parity. word length. The baud rate. 1015D D83 NB2 o 3 U14 DB2 NB1 SI 40 1= SO I25 20 2 3 C7 RD 16382 1/4 74LS32 01 WR l +5V 3 MC 1489 +5V 14 2 7 R11 1/474LS32 +5V 1K R121K S8 o 16383 16 IN EXTERNAL OUT U19 7475 RESET sp02 8 D7 Q1 2N2222 R21 1 18052 lf D6 2 +5V 11p +5V 6 10 14 10 8 C14 T.CONTROL PORT ASSIGNMENTS CO Port CI Port U12 UART ZX81 Data bus U13 UART ZX81 Input pin output pin -- data line contents output pin input pin data line 4 21 6 18 DO D1 13 D2 14 15 D3 D4 D5 3 5 7 9 16 18 24 20 22 Open Open Parity error Framing error Overrun error End of character Transmitter buffer empty Data available DO D1 D6 D7 22 19 ---- 8 10 15 17 19 21 Data bus contents External reset Reset data available Open Open Open D2 D3 D4 D5 Red LED Green LED Buzzer D6 D7 FIG. Bus lines are shown in bold.01 C12 T.01 1 +5V 5 02 DTY FREQUENCY U18 556 11 LED R14 10K 13 12 15 05 10 7 9 14 +5V /S7 J' S6 R16 10K R17 10K 25K 1/N 1ái+5V 6 DO±_ FREQUENCY R18 4 R23 47052 R15 10K I 3 VA R25 10K C11 %.o1 _ 7 C13 T. +5V 19 22 2 RD1 11 10 -8 ° CS 1K 3 ODD RD3 39 R D4 EPS N82 R06 R07 5 R13 FE RD5 7 +5V 14 13 15 OR ECC á RD2 24 NB1 EVEN S1 0 3 R1 R3 1K 1K R5 1K SR7 R9 71K 1K S 3 1108 26 27 28 29 30 31 32 33 TSB DB1 P DB4 35 16 10 7 < WR < 16382 < RD < 16383 8 9 DB7 1/4 74LS32 D88 6 2 DS 5 < < 21 XR RDE TCP 6 0 PARITY 1/4741S32 DB6 17 1 S5 DB5 RCP 5 o 8 NO 18 - BITS 0 PARITY AY3. Note the table at the top right: It tells you how to set up switches S2 and S3 for the proper number of bits per word.01 rr LE02 BUZZER 67 . 2 -The schematic of the interface.TABLE 2. electrolytic has been sent.address 16382 issued.Light. red U20 -LM317 three -terminal adjustable regulator U21. This power supply was built specifically to be used with the communications port gives you the voltages you need for RS -232 compatibility.100 OUT 0 -it FIG.F. etc. That becomes an important line during high baud rate transmissions. DBI -Des.100 -µF. C19-2200 -µF. The data that was loaded into the data -bit inputs is output at pin 25 of the UART as serial data with the proper bit spacing. 10% R26-5000 -ohm linear -taper potentiometer R27-420 -ohm. However. the control bits for the UART must be set.. 1 A D2-1N4002 rectifying diode LED3. 3. solder. 5% R28 -580 -ohm. the SERIAL INPUT (si) of the UART. Once the control bits for the UART are set.r C20 10-100 1fP GND U22 12V 7912 C21 T10. as you might guess. 300 -mA Power switches. electrolytic C16-10 -p. If you want no parity. C21 -10. Switch SI determines whether the parity is odd (S1 open) or even (S1 closed).Before data can be transmitted or received. 5% CAPACITORS C15-1000. 25.3300 . 50 -WVDC. Switches S2 and S3 determine the number of data bits per word as shown in the table on the schematic diagram. mounting hardware. BR2. 34 -VAC. the RECEIVED DATA ENABLE 1 if it's closed. 25 -WVDC. An END OF CHARACTER (EOC) signal (pin 24) is issued at the end of each character transmission and is read into the computer through the CI port. electrolytic C20. accessory outlet. 68 line 12V . electrolytic C17-1 -p. It will return to a logic one. 1/4-watt. when the transmitter buffer is empty. 1/2-watt. cabinet.2 -25V AMP C17 C16 R26 5K 10 LEO4 r OUTPUT POWER` ADJUST 117 F2 VAC 1/4 AMP T rS11 POWER E Tó U21 +12 34V CT OUT LM310T 300 A 42052 POWER C19 2200 + T o +12V ¡ R27 1E03 + . 50 -WVDC. a memory PEEK of the DI port is performed and the data is stored in memory. That output is converted to RS -232C levels by U15. it makes a great bench -top supply. to be more precise) that the UART may be loaded with another character that is to be sent. hardware.) The TRANSMITTER BUFFER EMPTY (TBMT) signal then changes to a logic zero.emitting diode.. T1 T1 ACCESSORY OUTLET CASE R25 2705'_ 02 1N4002 R28 54052 F1 1 i ADJUSTABLE 1. close S5. 1. wire.Bridge rectifier. an MC1488 line driver. The TBMT signal is connected to the CI port (address 16383) to control the sending of the next character. That signals you (or the computer. tantalum C18. and 2 stop bits U17 an RS -232C line receiver. too! Note the accessory outlet -it's ideal for the ZX81 power pack. Pin 4 of the UART. That line can be used to see if the last character in a series of characters RDE PARTS LIST FOR POWER SUPPLY -is SEMICONDUCTORS BR1. For the computer to receive data.2 -A T2 -Line step -down transformer. 10 -WVDC. LED4. It is then fed to pin 20. Then the DATA STROBE (ñs) line must be pulsed.2 -VAC. it must first check the CI port to see if data is available. (That's done when a POKE to the DO port. That's done using switches S1 -S5. The status word on the CI port is enabled by hardware (U16b) each time the CI port is read.LM340T 12 -volt positive regulator U22-7912 12-volt negative regulator RESISTORS B25-270 -ohm. data can be loaded on the data -bit lines. center tapped. The number of stop bits is determined by S4: stop bit if it's open. The UART Receiver ADDITIONAL PARTS AND MATERIALS -1 F1 A F2 -1/4 A Incoming serial input data is converted to binary levels by S10 POWER -Line step -down transformer.F. indicating that its data -bit holding register is full. 1/4 -watt.F. If data is available. . a reset must be issued: POKE 16383. You'll find that most computer networks that are accessible by the public use 300 baud. Ae r 0*-----" A" 0 o . o o o Le r r.5òo O 0 69 .:-j-ió Ili iii i 41. ole o óti OOO ee!101~0000 oolf e . I..Invalid stop bit. / ) J. FIG.... r r O 0 0 00 0 0 °. re . the DATA -AVAILABLE or DAV line (pin 19) must be reset by POKE-ing the CO port with a "0 ". 4 -The component side of the interface printed circuit board. (pin 4) is activated by hardware during a READ of location 16382. Some conditions for error signals on the CI port are: Parity Error-received parity does not agree with the selected The UART requires a transmit/receive or TX /RX clock rate that is 16 times that of the desired baud rate. (That's required for internal timing overhead of the DART.) The interface is designed for two baud rates-300 and 600 baud. r. . simply convert the data on the CI port into binary and compare it to Table 2.---- o - o00 /f_ o e ¡- f I 0 7-oNor / ooo 00000 e et ea.. e-o 4. Overrun Error-Previous data not read before next character received..'1 e . rv o o o o o o o o Ñ\y../ O O O e ee e oe°ef01Yf 000000i :J 000. 1NNL - O O ....Framing Error. ol... parity. Once the data is read. Transmit/receive clock If the CI port is read and errors are present. That enables data flow from the DART to the DI port. To determine which error lines are active.. Fig. 5 -The solder side of the interface board. RS -232C Since transmission lines are susceptible to noise. double-through switch instead of separate switches.o o aatll o m 00 L 70 OOO 0 \\ 0 00000004 0 00000 0000000 o d e o 00400 o % 0 0 J . (But DIP switches are not available in that configuration.) If variable resistors are used for the timing resistors. When selecting the interface baud rate. that the output frequency must be 16 times the desired baud rate. while it's best to use variable resistors for timing resistors so that the proper rate can be adjusted until it is correct. Therefore. you may want to use a single. Parity-detection schemes are used to check for dif- r.rate frequency. Keep in mind though. o 4 0 . To make it impossible to close both switches at the same time. Either S6 or S7 should be closed but not both. single-throw. totally false transfers will occur -the data you receive will not be the data sent and vice versa. any baud rate can be generated within the range of the timing capacitor. If the clock is not on the the proper baud position. it's also a good idea to use a dab of nail polish to hold the potentiometer in the proper The two rates are easily produced by a 556 dual timer (U18). be sure not to select both rates simultaneously. it is not unlikely for data on the lines to be altered by inherent noise on the lines. 000 -ohm A printed. Those devices come in handy as indicators for transmitting or receiving data or as check -point indicators in programs.74LS32 OR gate integrated circuit U10. an RS -232 line receiver.74LS75 D flip -flop (latch) integrated circuit R21.25.270 -ohm R23 -470 -ohm R24. various LED's.MC1489 RS -232C receiver integrated circuit U18 -556 dual timer integrated circuit U19. help to overcome the problem. Lox terkamp. and a -3 The driver converts + 3 to + 5 volts into a to -5 volts into a + 12 volts for transmission over the transmission line. 35 -WVDC.3. we need some type of differential 12 -volt supply for the line driver. Fairborn. S1 RESISTORS (All fixed resistors are 1/4-watt. C8 -C10.output line of the UART will be a logic "I" which goes to U15. a D -type flip -flop. - - Power supply Because we're using the RS -232C convention.0111F (not essential) C3.1000-ohm R14 -R17-10. C2 -.047 -11F C7. PC -mount potentiometer R18. ferences between transmitted and received data. SO. however. printed -circuit board. and a board .01 -µF. They do not. buzzers and relays can be controlled through the CO port. converts 12 volts to a logic "I" and + 12 volts to a logic "0".Light. At the receiver end.000 -ohm. Unless you want to mount the interface in a cabinet.As stated earlier. normally open Buzzer (Radio Shack 273 -64 or equivalent 3 -wire buzzer). 71 . C11. In the schematic (Fig.. 2) . C6 -47µF. you may prefer to use resistor pack -you can even mount them in DIP sockets.2N2222 NPN transistor Ul-U3-74LS244 octal buffer integrated circuit U4. That is the purpose of RS -232C. 249 W Dayton -Yellow Springs #248. U16. . and SI to other devices. red LED2.C14.. the serial. electrolytic ADDITIONAL PARTS AND MATERIALS J1 -pin DIN jack (female) -5 -3-conductor.74LS00 NAND gate integrated circuit U9. C4. Jack JI can be a commonly used 5 pin DIN connector for connecting GND. We could PARTS LIST FOR RS -232 INTERFACE R22. ceramic disc C5. ! 01 RESET SWITCH 0000000000000 0000000 o i Fig. an MC1488 RS -232 line driver. PERIPHERAL CONNECTOR .sA C3- 7' L D2 u-2J JJ R26 13 .R20. 12 volts. 6-While the parts -placement diagram shows discrete resistors.Light -emitting diode. J3.circuit board is available Edward W.M5L8212 PIO integrated circuit U14-AY-3-1015D UART integrated circuit U15.emitting diode.J x 4ae Db :s.000 -ohm SEMICONDUCTORS D1 -N914 diode LED1. is is controlled by D5 -D7 of the CO port. use a DIP -switch for S1 -S8.U13. G-q U8 qJ G14 .MC1488 RS -232C driver integrated circuit U17. R13 R15 Lca'" . CAPACITORS Cl. 1/4-watt. you can see that U19. U17.74LS139 dual 2 to 4 demultiplexers integrated circuit U8. used -+5V and J2 Ye -inch Ye jack -inch jack (only 2 conductors GND) -S8 -SPST. OH 45324 for $25. solder.95 for shipping and han- dling. 5% units) R1 -R13.conductor.U7.95. That flip -flop then controls transistor drivers Ql-Q3 which turn a buzzer and various LED's on and off.220.mounted switch for S9.switch DIP package S9 -RESET momentary switch. Add $1. ©03 TG4 G2 q -1 RED IBLUE : . green Q1-Q4. 8. etc. +5V BUZZER R5 61 R7 -12 C2 JI U11 U15 ii1 SO GND I. In an idle state. on the interface board. Foil patterns for that double -sided board are shown in Figs. This gives audible and visual indications of communication status. if you want to mount the interface separately. allowing for easy connection of additional hardware. you can connect it to the ZX81 with a 50. -12. but that wouldn't be cost effective. Even if you don't want to build the RS -232 interface.conductor ribbon cable. If you prefer the usual wire-wrap type connection. J2 and J3.R17 RESET SWITCH U13 U7 U1 U4 U18 U2 U5 U3 U6 Here are the major part locations on the top of the printed. By adding a temperature transducer to an input line. Controlling various appliances is only a simple task with SCR output optocouplers. such as the one shown in Fig. The most useful part of the board design is the edge connectors. That has all the ZX81 signals in the "normal" configuration. 6. the power supply would be a welcome addition to any work bench. A parts -placement diagram follows in Fig. The connector on the 71/2-inch side can be connected to the computer with a double female ribbon cable while the other edge connector allows for other peripherals to be connected.switch DIP housing (S1 -S8) can be discrete. 3. binary data. Those outputs go to two jacks. 4 and 5. The board is laid out so that it's easy to make external connections (such as power and ground). For example.circuit board. a constant home or room temperature can be maintained economically. A software routine could be written to monitor the entire house and even call the police-assuming you have the appropriate dialing equipment.Building the Circuit The circuit can be easily built on a printed-circuit board. The software is set up to send and receive. Simple Control Software Table 3 lists a simple program that will transmit or receive data. at any one time. DIP SWITCHES U10 U11 U16 U14 BUZZER l LED1 -2 01 -04 J3 SLOT U15 U12 U17 U8 R14 . The pull -up and pull-down resistors associated with the 8. That power supply has outputs of + 12. (Continued on page 100) The edge connectors are designed to give you a number of options for connecting your computer and peripherals. An output control line can be used to control an air conditioning or heating unit. the edge card connectors make it easy. The applications are limitless. but resistor packs might be more convenient. We mentioned previously the extra control lines that are available. The software makes use of the LED's and buzzer during communications. So you can see this circuit has many varied uses that range from printer interfacing to appliance control and from communicating with other computers to controlling a home security system. Those control lines can also be used for sensors in a home security system. the male card -edge pins can be cut off and a wire-wrap edge connector used. If you'd like to house the interface separately. and + 5 volts. 72 . On the 51-inch side of the board is another male edge card connector. The variable regulator makes it extremely versatile. It is more convenient to build an additional power supply. accomplish that with a DC -to-DC converter. Figure shows a typical digital logic circuit. computation. The Inverter The simplest digital -logic circuit is the inverter. . It is the decision -making characteristics that gives logic circuits their functional capability. It converts a binary 0 (low) into a binary I (high) and a binary I into a binary O. 2. the NAND gate. All digital equipment is made up of those simple elements. represents the inversion process. The AND.IN MI s DIGITAL . Those digital -logic circuits typically accept two or more binary inputs and generate a single output. FUNDAMENTALS : Discover the operation of five basic digital -logic elements and how to use their truth tables. There are five basic digital -logic circuits. because it is basically irrelevant. Digital -Logic Circuits . The triangle typically represents the electronic circuitry while the circle. or any other logic circuit for that matter. combinations of the basic three. Only the logical functioning of the circuit is of interest. Those digital -logic circuits are then combined in a variety of ways to form larger. The basic function of a digital -logic circuit is to make a decision. learn about the element's rise and fall times and propagation delay. Understand simple Boolean algebra expressions that define the logic circuit. is usually expressed in one of three ways: a truth . which can be shown at the output or input. .Generic. The logic circuit looks at the states of the input signals. The logic symbol used to designate an inverter is shown in Fig. LOGIC GATE 1. : LESSON 2: : ' . The output of an inverter is simply the opposite of its input. and inverter circuits are really the core elements while the NAND gate and NOR gate are special just 1 Fig. OR. Frenzel . E. It has a single input and a single output. or control applications. Most digital -logic circuits are called gates. Also. ALL DIGITAL-ELECTRONICS EQUIPMENT IS MADE UP OF a few basic building blocks known as digital -logic circuits. Its primary function is to invert a logic signal. Typically the electronic circuit itself is not shown. Those basic circuits are combined in a variety of ways to process the binary data used in communications. hypothetical digital logic circuit is usually referred to as a BINARY INPUTS DIGITAL LOGIC CIRCUIT BINARY OUTPUT gate. as you will see later. then makes a decision and generates an output. and the NOR gate. the inverter.logic circuits. more sophisticated circuits called coin binational. we say that an inverter generates an output which is the complement of the input. . the OR gate. The output state is determined by the binary states of the input and the special processing characteristics of the digital -logic circuit. In digital terminology. They are the AND gate. The operation of an inverter. By L. NAND and NOR. it is I (high). Figure 3 shows the typical input and output waveforms of an inverter. Propagation delay results from imperfections in the logic circuit itself All digital -logic circuits have propagation delay. First note that the sides of the waveform in Fig. 5. but incredibly easy to understand. the output of the inverter does not simultaneously drop from to O. in an inverter. IN B Fig. The Boolean expression for an inverter is: 1 1C The way to read the above equation is: output B is equal to A. For example. The waveform rises or falls linearly. Those waveforms are what you would expect to see if you were monitoring the input and output signals on a multi -trace oscilloscope. The bar over the input designation A is called a NOT bar or NOT symbol. A Boolean expression is nothing more than a simple formula that expresses the output in terms of the input. The rise time is the amount of time it takes the logic signal to rise from 10% to 90% of its full amplitude value. A truth table is nothing more than a chart that shows all the possible combinations of inputs and outputs of a logic circuit.circuit factor is propagation delay. The waveforms typically shown in timing diagrams are usually shown in their ideal form. with vertical sides and flat tops. That means that the waveforms are perfectly square. 4. 2 -Logic symbols for an inverter. The two basic kinds of logic gates are AND and OR. The expression gate is metaphorical and tends to describe how a typical digital. 3 A OUT IN A -Input and output OUT B A waveforms of an inverter. the lefthand column represents all possible input combinations. For many applications. an asterisk or prime symbol is often used to show inversion as indicated below: B=A' or B = A' Timing Diagrams The input and output binary signals in Truth Table are identified by letters of the alphabet as seen in Figs. NOT Y=X=X The two 74 NOT symbols cancel one another. That means that the transition between the binary 0 and I state (or binary and 0 state) is not instantaneous. The fall time is the time it takes for the logic signal to drop from 90 %c to 10% of its full amplitude value. The times involved in changing states are referred to as the rise time and fall time. Naturally. then the output is NOT 0. In the truth table for the inverter (Table 1). If the input to an inverter is X. 1 INPUT A o Another way of showing the operation of a logic circuit is to use timing diagrams. If the gate is closed. That means that the output occurrence of a logic signal is somewhat delayed from its input. An inverter is also referred to as a NOT circuit. Another method of expressing the operation of a logic circuit is to use Boolean algebra. Two. the output Y will be X or NOT X NOT. a Boolean algebra expression. they form the other two types of gates. Figure 4 shows what real logic signals would look like on an oscilloscope when the sweep period is very brief The waveforms are those that you would see at the input and output of a typical inverter circuit. when the gate is open. What that simple algebraic expression tells you is that if the input is A. For example. They are shown in Figs. then the output B is NOT A. The AND Gate The term gate is used to describe a digital -logic circuit with two or more inputs and a single output. Granted they are very short. a logic signal passes. 2 and 3. that is such a small time period that the response is essentially considered to be instantaneous. the operation is more complex. In the real world. The output and the input are given letter or letter /number designations. Boolean algebra was invented by mathematician George Boole and is a simple mathematical way to show what's going on in digital -logic circuits. A truth table (Table 1) for an inverter is shown below. 5 are not perfectly vertical.table. three. That time shift is known as propagation delay. It is used to denote inversion. Note that the output is the complement of the input. We will consider theAND gate first.circuit functions. if the input is 0 (low). 2 and 3. While digital -logic circuits switch rapidly. less than IO nanoseconds in most circuits. Those diagrams show the actual input and output waveforms that occur. it does take a finite period of time for the logic state to change. With a single input line. Another important real -world logic. a logic signal does not pass. When those are combined with an inverter. In other words. Rise and fall times can be measured on an oscilloscope screen if the scope has a calibrated time base. TABLE 1 INVERTER TRUTH TABLE Instead of the NOT bar which is an unusual symbol and difficult to type or print. or waveform timing diagram. digital signals are not that perfect. and four input AND gates with . only two states are possible. In reality. There is a time shift between the input and output. Let's look at all three for the inverter. only two output states are possible. 1 t OUTPUT B o Fig. It is measured between the 50% amplitude points on the corresponding input and output waveforms as detailed in Fig. when the input rises from 0 to I. The basic logic symbol used to represent the AND gate is shown in Fig. Inverter input and output waveforms illustrating rise and fall times and propagation delay. TIME Fig. But in most cases. the dot is omitted and the input terms are simply written adjacent to one another as they would be if the terms were to be multiplied as in a standard algebraic expression. As you can see. 5 D = - R 1 I PROPAGATION DELAY - A0 r- I IABI (A2) (A5) J=PRST -Logic symbols for the AND gate. their inputs and outputs labeled are shown. 4. With two inputs. 16 TABLE 2 AND TRUTH TABLE FOR TWO INPUTS 17 Output Inputs X Y Z 0 0 0 0 1 0 0 0 1 1 1 1 INPUTS < B TABLE 3 AND TRUTH TABLE FOR THREE INPUTS Inputs C OUTPUT X Y Z 0 0 0 0 0 0 0 0 0 0 D Fig. If any one or more of its inputs is binary 0. However. There is an output Z that occurs for each different set of inputs. In that case.RISE TIME FALL TIME INPUT 90% - -r I 50% 10% IL -I I - 2-XY -----I -1 1 I I I IF- X Y i -0. That characteristic has led to the AND gate being described as a coincidence circuit. A truth table (Table 2) clearly shows the operation of an AND gate. you say that Z equals X AND Y. Carefully observe the states of each input and how they correspond to the output. 75 . Here there are two inputs. At times t1 through is the three inputs are never at a high at the same time. For example: F = (J2)(L7) Figure 6 shows typical timing diagrams for a three -input gate. The Boolean expression for an AND gate with inputs X and Y and output Z is simply: 1 Z=XY=XY 1 1 1 0 1 0 0 0 1 0 0 1 1 0 0 0 1 1 1 1 1 TIME Output W 1 To read the above algebraic expression. since the output occurs only during the coincidence of the binary I states. 6 - -Input and output waveforms for a 3 -input ANO gate. Take a look at the truth table (Table 2) for a two input AND gate below shown in Fig 5. a binary I output appears only when both inputs are binary l's. an AND gate generates a binary I output if all of its inputs are binary l's. Again. there will be 2 to the second power (22) or 4 possible input conditions. In operation. the output is binary only when all three inputs are binary I. X and Y. The dot between the two inputs designates the AND function. Sometimes. beginning at time t6 and ending at time t7 the three inputs are high during the interval so that output D AND goes high. parenthesis are used to separate the inputs when multiple letters or letter/ number designations are used. there can be a total of 2 to the third power (23) or 8 possible different input states. the output is a binary O. With three inputs. Now take a look at the truth table for a three input AND gate (Table 3). a binary I output pulse occurs only where the three inputs are simultaneously binary I's.1 AZ A5 OUTPUT - t I -1 -ID S T It- Fig. The plus sign indicates the OR function. The resistors at the inputs to the OR gate keep the input states at binary 0 until a switch closes. AX D4=AX+T9+G T9 G ti I I 12 I I 13 t4 I I I I 16 t. Any time an input to an AND gate is binary 0. The purpose of the control signal is to literally open or close the gate. input K goes low. 1 J L- =KL Fig. 8 is: l 1 Ì CTL 1 Output L I i I 1 K .. 9 -Input and output waveforms for an OR FAN MOTOR gate.` iiJ LJII It I I I i I I ! t I 1 1 I l 1 I I K + L To read that equation we say that J equals K OR L. the fan will turn on. Here a cooling fan motor is controlled by the output of the oR gate. an oR gate generates a binary I output if any one or more inputs is binary I. The Boolean expression for the OR function is shown below: (CK) ICTL) = zero only when all of its inputs are zero. tg t9 1 K °z 1 L 0 -iI I I I II TEMPERATURE SENSOR I I I TIME Fig. The truth table (Table 4) shows the basic operation of a two-input OR gate. The rise and fall times and propagation delays are not shown to simplify the illustration. The first input is a temperature sensor. 1 1 1 1 1 1 1 1 1 1 I 1 I 11 I 1 1 1 1 D4 = AX + T9 + G - 11I 1 I OUT 7. J = - U TABLE OR TRUTH TABLE FOR TWO INPUTS Note that those three input combinations where binary l's occur on either or both inputs generate a binary l output. the gate is enabled and the clock signal applied to the other input passes through to the output. 10. The fan motor may be turned off or on by two separate inputs to the OR gate. As for its function. The symbol used to represent the OR gate is shown in Fig. At time t. a driver is inserted into the circuit to provide the power switching required to control the motor. The output of the OR is 76 MANUAL FA'. A control signal (CTL) is applied to the other. 8. As long as the CTL signal is binary I. SWITCH -A- Fig. Here a clock signal from an oscillator clock (CK) is applied to one input. the output is correspondingly a binary O. Since the logic oR chip is rated for small signals only. It can have two or more inputs and a single output. A simple application is shown in Fig. An OR gate is a useful logic function as it allows two or more individual signals to control a single output. the clock signal will pass through.One of the most common applications for an AND gate is gating input. Figure 7 illustrates the concept. When the CTL signal is binary I. When the CTL signal is binary 0. Figure 9 shows the operation of an oR gate using two-input waveforms. When the temperature rises ( + V level) to the OR gate. the gate is closed. the fan motor is turned on. Follow each input waveform and note the output condition for the binary input condition."Gating with an Fig. The Boolean expression for the three -input OR gate in Fig.. I I 4 '1iuiá' Via. For example: input K goes high causing output J to go high at time t1. The other input to the OR gate is a manually operated switch to be turned off and on to control the motor. -Using an oR gate to select active input to control the operation of a fan motor. When either input is a binary I. CK 110--+OUT CT L - CK . 10 . applying a binary I. but input L is high: thus output K remains high until time tti3 when both inputs are low. AND gate. o The oR Gate The other basic logic circuit is the OR gate.-. 8 -Logic symbols and Boolean algebraic expressions for an oR gate. A NOR circuit is shown in Fig. 77 . and t10 -t11. That circuit is usually represented by a single symbol which is the AND symbol with a circle at its output to indicate inversion.<. While any of the basic logic functions can be obtained in IC form. Note that the NOR output occurs only during periods t3 -t4 and t7-t. the output is binary except where both inputs are binary -NAND gate 11 circuit (A) and logic symbol (B). Several 2 -gate OR inverters are packaged together into a common dual in -line integrated. 13-NOR logic circuit and logic symbol. That is illustrated in the NAND truth table (Table 5). and NOR circuits. Inputs XY two -input a TABLE 1 Outputs NOR. t2. tr. ORIENTATION DOT C= A A+B B AB 6 B NOR CIRCUIT y NOR SYMBOL PI N NUMBE Fig. and All five NAND NOR Applications basic logic circuits are available in integrated circuit form. t7. 13. Z = XV X A 0 binary O. OUTPUT Fig. +3 TO +15V t1 t2 t3 14 t5 t6 t7 t6 t6 t10 t11 1 I I I I I I I I I I I I X I 1 I I I I INPUTS Y 1 I ORIENTATION I I . 12. o The Boolean expression for a NAND gate is also simple to understand. now would be a good time to quickly review all the truth tables (Tables I through 6) to be sure you fully understand the operation of the AND. 15. the most widely used are the NAND and NOR gates. It is the output result of an AND gate inverted.circuit package. Inputs which time the output is at I 5 OR NOR TRUTH TABLE FOR TWO INPUTS NAND gate. 14 -Input and output waveforms for a 2 -input NOR. It is an OR gate followed by an inverter. 11 shows a NAND gate. It is made up with an AND circuit followed by an inverter. NAND. The output pulses occur during time periods t. Verify that statement by using the NOR truth table (Table 6). Here the output is a binary 0 when any one or more of the inputs are binary I. R 15. Z 12 -Input and output I I i I I ' I I I I I NOTCH I waveforms for a 2 -input NAND. NAND SVMBOL NANO CIRCUIT For Fig. A typical digital logic IC is the popular 4001 quad 2 -input CMOS NOR shown in Fig. At all other times. For example. Note that the only time the output is a binary 0 is when both inputs are simultaneously binary I. one or both inputs are low. OR. Fig. The output of the NOR gate is simply the inverted or t6 t7 t6 il Fig.Pictorial diagram for NOR the 4001 CMOS quad 2 -input integrated circuit. -t3. 14 illustrate the operation of the NOR gate. Check the inputs diagrammed during those periods and you'll discover that they are high. The special symbol used to represent that circuit is the OR symbol with a circle at its output to indicate signal inversion. The operation of a NAND gate is simple to deduce.and NOR Gates The use of an inverter immediately at the output of AND and OR gates combined within a package makes possible NAND NAND complement output of the standard inputs. k OR gate NAND 1 1 1 The waveforms in Fig. It is simply the AND expression with shown below: B OR o o 1 o 0 1 o 1 1 o 1 1 -- bar over all inputs as a NOT Ou X Y AND o o o 1 o o o o 1 Y with identical TABLE 6 NAND TRUTH TABLE and NOR gates. Fig. In fact. t3 t4 t5 D=EFG The operation of a NAND gate is illustrated by the waveforms in Fig. The truth table (Table 6) shows the operation of the NOR gate. The shown below is a(n): s A > > INPUT A INPUT OUTPUT B I I I I I I I I NAND Circle one: a. When a NOR gate is used in that way.0 =1ABC d. When used in that way. C = ABC c. Here a NAND gate can be used as an OR circuit by connecting inverters ahead of the inputs. That is an OR symbol with circles at the inputs to designate that special function. That is an aid in understanding the operation of the circuit and in troubleshooting it. The output of the circuit shown below is: BINARY a. Which circuits below perform the AND function? circuit generating the output waveforms 3.4 b. I7A. NOR C. 16 -NAND and NOR gates connected to perform as inverters. A 4 -input NAND gate will have how many possible input and output state? a. To do that.ID» A L - X A X Fig. I8B. 17 -NOR and NAND = gates connected to perform as inverters. 16. A NOR gate can be used for the OR function by simply connecting an inverter at the output of it. I8D is used.32 ANSWERS TO QUIZ HON 5. Which of the following is the truth table for a NOR gate? 0 of the input. See Fig.8 c. the special symbol shown in Fig. You can also use a NOR gate as an AND. inverter d. inverter 9. For example: A NAND or a NOR gate can be used as an inverter as shown in Fig. 0 0 0 0 0 1 1 0 1 1 1 0 0 0 1 7. Answering those questions will help you apply what you have learned to reinforce your knowledge. 0 0 1 0 1 1 0 1 1 1 0 1 1 0 1 0 0 0 1 1 0 1 1 1 1 1 0 1 0 b. OR and inverting functions. c b. 17B. Fig. FT B FT = FT C . Again all you have to do is connect inverters to the two inputs as shown in Fig. the NAND circuit is usually OR operations.NOR 4. A+B A+B XY XY NOR NAND A Fig. binary o b. AND b. c. OR e. A coincidence circuit is a(n): a. 9l x Z x = Z x Z= vZ-91. The short quiz that follows will help you review the main facts presented in the above article. The inverter complements the output back to the standard OR output. b.AND C. Several other variations of making AND and OR gates from NANDS and NORS are shown in Fig. The Boolean expression for a NOR gate is: a. I8A. The resulting circuit operates just like any inverter. SHORT QUIZ ON DIGITAL LOGIC CIRCUITS 1. binary a. The AND function can be illustrated in Fig. all of the inputs are connected together to form a single input.0 =A =B =C 78 C 8.16 d. 18C. represented by the special symbol shown in Fig. '3 '6 nelap uolte6edad g o pue 'q 'e 'L O= p '9 9 = V = O 'e 'S ONV 'e NO '3 '£ Z ivawaidwo3 Z t (eulq q . 0 0 1 output of an inverter is said to be the 2. The 6. 17 11. The symbol on a logic diagram should designate the actual logic function pertòrmed. 18 -Using NANDS and NOR'S for AND and They can be interconnected to perform basic AND.0 =A +B +C b. 1 0 d. The same is true of a NAND gate. The time shift between the output and input of a logic circuit is referred to as C a. make the long antennas more attractive. an often neglected benefit of a long antenna has to do with the better matching of the receiver input to provide maximum signal -current transfer. The problem with such a long antenna is the actual length of the antenna wire necessary to obtain a quarter-wavelength. Just make some appropriate folds and turns. If you are pinched. and also gain the added advantage of better signal -current transfer to your receiver input. you can certainly do better than using only a 40 -foot antenna. such as PVC piping. Not too long ago. A random antenna wire that is one -quarter wavelength long provides a good match to the receiver input. At the low end of the band a quarter-wavelength is greater than 400 feet. increasing signal level with a longer antenna and /or increasing receiver sensitivity only provided limited benefits because strong locals would then spill over from adjacent channels and /or desensitize receivers. there is a low impedance and an attractive match that transfers signal current well. In example a little added length can be obtained. If the construction allowed for of a 40two -ladder rungs. D -The long -wire antenna follows the perimeter 40 -foot lot. you will obtain maximum signal pickup. where the wire connects to the receiver input. However. 1. based on extending the antenna from ground level up 15 feet. A -a simple folded long -wire antenna that takes advantage of its height to use the lead -in and a vertical leg at its end ladder to obtain an addition 30 feet of antenna length. 1 Some ideas for doing that are shown in Fig. Fig. Example B of Fig. with only a 40 -foot mounting site. by bending and folding the antenna wire you can still obtain an improved pickup as compared to a short antenna. Exactly a quarter wavelength away.By Ed NoII BCB Antennas for Small Lots IDENTIFICATION OF WEAK SIGNALS IS A MAJOR THRUST OF broadcast -band DX'ing. using a non -metallic mast. C -The antenna makes a "dog -leg" turn following the perimeter of the property line to gain added length. Table shows the quarter-wavelength dimension in feet for broadcast -band frequencies from 540 to 1600 kHz. However. A long antenna has two advantages. across 40 feet. while at the upper-frequency end it is about 146 feet. offers further improvement. The far end of a single -wire antenna has a high impedance. and down 15 feet. Note that the antenna wire is folded back upon itself in ladder-like fashion. 1 -a 79 . Thus the name that is appropriate is "ladder antenna. 1 EYE RING BOLT EYE -RING BOLT NON- METALLIC MAST TO SET A TO SET B TABLE 1. It is obvious that it picks up more signal. How does one accommodate such a long antenna on a small lot? If you can stretch out a quarter-wavelength antenna in a straight line. That very simple antenna does well and is easy to erect. Today's better broadcast -band receivers with radio-frequency amplifiers and improved selectivity curves. the overall length would be 320 feet.QUARTER -WAVE DIMENSIONS ON BROADCAST BAND C kHz Feet kHz Feet 540 660 700 433 390 334 1100 1200 1300 213 195 180 800 900 1000 292 255 234 1400 1500 1600 167 156 146 D -four basic types of folded long -wire antennas." Such an antenna can also be constructed very simply by A. as well as ability to handle a wide range of signal levels. B type array folds the antenna wire back on itself to effectively increase its overall length. The final path is up the first mast through the top eyebolt and then across to a loop-and -tie termination the very top of the second mast. The two mast sections are perfectly self-supporting. 80 MEW GUY GUY 12 1 ANTENNA WIRE 120 120° GUY GUY Fig. Use insulated wire for the antenna. If you make a one ladder fold you will be over 160 feet. 3. Plan your antenna with respect to the space available. you are up into the middle section of the band. However. work with that smaller real estate. Add the lengths of the wire that run vertically on the masts and the lead -in length to the radio room -you are well up into the lower frequency portion of the high -frequency segment of the broadcast band. 3 -Guys are requires to keep the masts erect. OD pipe fits snugly inside the 2-in. Secure the mast sections with through bolts and nuts. though you have only a 40 -foot mounting length. If you have more than 40 feet. if less. Fig. 2. you are already resonant down at the high -frequency end of the band. Example C of Fig. use eye-ring bolts. the guys prevent the bend -over of the top sections that would occur were the antenna wire pulled tight without the presence of the pair of guys. If you have a 40.1 NO. The path of the antenna wire (Fig. The mast is supported by a metal fence post driven into the ground. 2) is up mast to the first eyebolt and then across to the first eyebolt of the second mast.2 40 LOOP ANO TIE TERMINATION 4 -1/2 GUYS 2 -This illustration details the construction of the PVC masts and the running of antenna wire to make a three -rung ladder -type antenna. The connection of the antenna wire at the base of the lower mast section (chest high) is shown in Fig. adding on to that figure the length of a single -wire feed line into the radio room. the total length of this antenna is 135 feet. 1. The overall length will be equal to a quarter-wavelength somewhere in the high -frequency end of the broadcast band. As a result. EYE RING BOLT (1 OF 81 4-1/2 THRU BOLT (1 OF 6) RESTING BOLT -2 RESTING BOLT I TO RECEIVER GROUND LEVEL METAL FENCE POST using PVC piping.frequency end of the broadcast band. that's fine.ladder configuration. Two ten foot sections of PVC piping are telescoped together (the 1. In fact. or between masts. An appropriate soldering ring is fastened to the end of the antenna wire. They will bow inward due to the pull of the taut antenna wire and its weight.by 40 -foot square layout. The arrangements of Fig. The PVC piping is so light that it requires but one person to lift it up and set it over the fence post. Use nylon rope set at the approximate angles shown. across to the second eyebolt of the first mast. shows what you can do when 40 foot this way and 40 feet that way is available. A resting bolt through the mast holds the mast assembly above ground level to obtain a little additional height. Each mast is held straight up with a combination of the antenna wire and two rope guys as shown in Fig.MAST MAST NO. OD pipe). A two -ladder arrangement takes you into the low-frequency end of the band. From there it is run up the mast to the second eyebolt and then 1 1 Build -it Details The construction plan for a three -ladder antenna with a 40foot separation between masts is shown in Fig. Using a three. Your antenna wire is now longer than 80 feet (assuming a height of 15 feet). When antenna wire is to be fed up and down the mast. 1 show you that a long antenna is really not impossible on a small lot. Note that the overall length brings you very near to a quarter-wavelength on 1600 kHz. Plastic-covered #16 AWG stranded wire is ideal. you will find you have a quarter-wavelength somewhere at the high. Estimating a mast height of 15 feet. you can then connect a single- . If you desire. it is possible to attain a mast that is 20 feet above ground level at its top and at the same time telescope two ten -foot sections together.5in. 4. Refer to example D in Fig. That connection is made to secure the heavy coaxial cable so the center solid-copper lead will not snap. A good connection can be made with an alligator clip that is disconnected when not in use --a form of lightning protection.frequency segments of the band as well.5. Better noise rejection is obtained if a good ground is connected to the receiver in the radio room.0 WNPV WCHE WKBW 1440 1520 1520 +3.0 Call kHz dB CJSB WFIL WIP 540 560 610 WSM WNBC WLW 560 660 700 WOR WABC WWL 710 770 870 WCBS WLS KDKA 880 890 +4. However. if you are working with weak signals and stations difficult to identify. When you are receiving strong signals. as well as length of transmission line.5 +2. Of course.0 +6. Note the very substantial gains obtained at the high -frequency end of the broadcast band -simply because the overall antenna wire length was approaching a quarter-wave resonance at the high -frequency end of the broadcast band. 81 .5 WWVA WCAU WNEW 1170 1210 1430 1.0 +1. it does show quite realistically the improvement of gain that can be obtained by using a longer antenna wire mounted in the same space.5 1020 0.0 +0. The three-rung antenna was then compared with the reference and the resultant figures jotted down. Table 2 is a signal strength comparison between a 40 -foot wire antenna wire and the three -rung ladder arrangement of Fig. Fig. also have an influence on the absolute value of the signal current delivered to the receiver input. 2.5 1. any boost in signal as delivered to the input of the receiver can be a definite advantage. the inner conductor is connected to the antenna wire terminal. if you can separate the two antenna masts a greater distance.0 +4.5 +1. A single lead -in wire will connect there. Fig.0 +2.5 +8. First the 40 -foot antenna wire was used and compared to an attic -mounted reference antenna located in the crawl space at the top of the house. To obtain a rather good comparison between the two antennas. lead in line is desired. because angle of signal's arrival. There is some gain over the mid and low.0 +5. the overall length of the antenna wire will increase and you can anticipate higher gain figures on the lower frequencies. Nevertheless. Those are the figures given in the dB +1.TABLE 2-GAIN OF 3 -RUNG LADDER ANTENNA VS. When the noise -reduction characteristics of coaxial.0 1. LONG WIRE ANTENNA Call kHz dB +1. Those figures were jotted down for an array of stations from the low to high -frequency ends of the broadcast band. No other wire is connected to the braid terminal.0 0. 5-Coax lead -in cable should have its shield connected to a dummy terminal that provides good mechanical support for the cable and keeps the weight off the solid inner conductor. The three -rung antenna was then erected at exactly the same site and between the same two 20 -foot masts.0 +4. the additional gain is not of much significance. Remember to connect the coaxial braid to the ground of the the receiver.station figures are not consistent. The braid of the coaxial line connects to second terminal.5 +1. 4 -One good idea is to terminate the antenna wire at a through -bolt terminal.0 WSNI WOXR WBUX 1540 1560 1570 +3.0 +2.0 WGY KYW WBRW 1030 1060 1170 +2. Also the use of four or five rungs can also improve performance of the ladder antenna. The station -to.0 +2.0 column of Table 2. it was only necessary to subtract the first set of comparison readings from the second set.0 wire feed line to that point and on into the radio shack. Fig. and motion -picture camera and projector. 1 FSLL. That is the opening period. The discussion to follow refers to shutter blades.SHUTTERSPEED TESTER By Hugh Gordon QTHE SHUTTER -SPEED TESTER IS ESSENTIAL FOR CHECKING camera shutters for time -interval accuracy. The measurement includes both the opening and closing time periods. Fig. E_ A 82 Interpreting the Display Shutter speed is the measurement of the time light passes _ TIME A E D - TIME .frequency cycle is a bit longer than the shutter's exposure time. 1 -The basic waveform seen on the oscilloscope when the time of one sweep. Thus. Those detected faults indicate the need for repair or an exposure-correction adjustment by a professional camera repairman. The tester. The Shutter-Speed Tester can also detect faults that have developed. when used with your oscilloscope. opening and closing operation. shutter consistency. 1 2 -By adjusting the oscilloscope's sweep frequency. or more important. To obtain good quality.framing speeds." the time interval from E to F in Fig. FULLY through the lens to the film while the shutter is open. inconsistent. That is the closing period. as a Shutter-Speed Tester. The shutter blades begin opening at point A and are fully open at point B. with the addition of a few parts and an evening's work. the shutter blades begin to close and are completely closed at point D. the camera's shutter-open time should correspond accurately with the exposure setting indicator /control on the camera. provides an accurate checking of shutter speeds. Points E and F at mid -point in the vertical presentation on the scope face indicates the effective shutter exposure time (or speed). The time from A to B is the interval required to open the shutter fully: B to C is the time the shutter is fully open: and C to D is the interval required to close the shutter. or 17milliseconds (mSec). for a camera shutter-speed setting of "60. Your oscilloscope can be used. The screen of the oscilloscope displays the waveform of the shutter-operating interval. Fig. Fig. then poor exposures will result. as well as the period the shutter remains fully open. graphically indicating the opening and closing characteristics and the average shutter speed. properly exposed photographs. The blades remain open from B to C. 1 should be 1/60 of a second. OPEN C B OPf'. That time should coincide with the shutterspeed indication on the camera dial. The length of the dotted line passing through the center of the graph from points E to F illustrates the average time the shutter is open. can be made to coincide so that the time of the sweep frequency is exactly equal to the effective shutter open time. but is similarly applicable to the focal -plane type. particularly in color. The horizontal time base of the oscilloscope is measured in time travelling from left to right. points E and F observed in Fig. as in a leaf shutter. is a graph of shutter operation. If a shutter is not accurate. Beginning with point C. If a metal box is used. 83 . Most of the parts should be available from your junkbox. That decreases the negative gate. 5 -This cross -sectional view illustrates how the solar cell may be mounted. With a standard oscilloscope.source bias already established by the source resistor and causes an increase in drain current.. Any thing more elaborate than that is wasted money and time. When viewing that waveform on the oscilloscope. Then. ~ Dl SOLAR CELL Fig. Checking its accuracy will indicate whether repair is necessary or not. 5) will insulate the cell from the box. The author used a small box he had on hand that measured 21/2. the average opening time can be determined by observing a trace as seen in Fig. is connected across the input of the FET (field. That point coincides with the dotted line across Fig. as shown in the schematic diagram of Fig. 4 -The schematic diagram for the Shutter -Speed Tester is very simple to understand. It is very brittle and cannot take much tension. the plastic sheet (Fig.H. A to B. the shutter blades begin to open at point A. 4. In the above presentation the shutter opens slowly until it reaches a peak and then snaps shut quickly. but any convenient size and type of box may be used. using a method similar to that illustrated in Fig. However. A fresh battery is all that is required for a power supply. Construction All parts can be easily mounted in a small chassis or plastic box. 2. C FULLY How it Works The solar cell. SCREW & NUT FOAM PROTECTOR Fig. Q1.high and 41/2-inch long. be very careful when handling the cell. 3.wide. The cell is held in place by a metal strap OPEN CHASSIS BOX ENCLOSURE METAL STRAP SOLAR CELL TIME D PLASTIC SHEET 6. A 3/4 -inch hole is cut in the top of the box to permit light to shine through to the cell. 1. That shutter type can be tested in the same way and the scope will provide an accurate measurement when the trace lines cross at the halfway position. If the scope is adjusted to obtain that. you want to interpret the average speed. there is an amplified positive -going voltage output at the collector. at the time they are fully open. so that it will produce a positive DC voltage to the gate when activated by light shining through the open shutter. Thus. which shows the ideal waveform with the point of crossing halfway on the maximum amplitude. You're actually looking at two parts of the total wave that is split partway along the time base. and even easier to assemble. as would be desired and which is accomplished on expensive testers. then the average speed is read directly from a simply -made chart attached to the scope. Mount the solar cell first. That produces a waveform that is displaced vertically whenever light strikes the cell. 3 -Some shutters exhibit different curves on the oscilloscope. Some electronic shutters open and close at vastly different rates. but are not fully open until point B. A thin plastic sheet was first glued to the underside in order to protect the delicate cell from damage. Q2's collector current decreases.effect transistor). 5. The closing time is from B to C and is much shorter than the opening time. bending or warping -it'll crack.Your camera's shutter is a mechanical device that can get out -of-time as your car's engine does. the sweep is recurring and cannot be triggered to begin at point A. The letters correspond to the letters seen in Fig. 1 such that reference points E and F coincide. and it's applied directly to the oscilloscope's vertical input. and its collector voltage becomes more positive. they immediately begin to close. Here. The drain voltage goes more negative which causes a decrease in Q2's base current. Fig. Thus. In Fig. 23/4. the graph of one type is shown. it does not take much to fracture it. However you do it. B.32 F. such as f8 or fll. as in Fig. 7. marking on the paper. A shielded phono -cable is used to connect the unit to the oscilloscope terminals. and terminators to tit your oscilloscope's vertical input terminals on the other. so be careful not to burn yourself and/or overheat the lens system under test. 8. The cable requires a phono plug on SOLAR CELL one end. to indicate speeds in fractions of a second. simply position a desk or bench lamp so it will shine directly through the lens onto the solar cell when the shutter is operated. First. A 60 -watt or 100-watt lamp is adequate. or if you prefer. Then.6- Interior view of the Shutter -Speed Tester showing the arrangement of parts. The following method was checked against a calibrated Hewlitt. For light. The foam protector was packed with the cell when purchased. Those points are used later for repositioning the inked chart. you must calibrate the time base of the oscilloscope to read shutter speeds directly. An internal view of the author's unit is shown in Fig. 8. The arrangement of the parts is not critical.Packard laboratory generator and found to be within one or two cycles of accuracy. 6 and the completed tester is shown in Fig. in milliseconds. The circuit board is at the extreme right and is supported from the metal box by rubber grommets. it is a dependable standard to use. rotate the control knob to each of its two extremes. Glue a layer of black felt or cloth on top of the box to prevent scratching the camera when testing shutters. A more permanent installation can be made. Remember. Fig. A scale can then be drawn. that will fit over the horizontal vernier control knob on your scope. position the lamp quite close to the lens in order to supply adequate light for good vertical deflection. if desired. Fig. The felt protects the camera housing from scratches and provides some what of a light seal when the lens housing is resting on it. make a semi -circular paper dial. 84 . Those lamps throw off a lot of heat. A dark felt is cemented to the top of the unit. Calibration Before using the Shutter-Speed Tester. Since the alternating -current supply to the home is accurately controlled in frequency. similar to the one in Fig. If using very small apertures. while the RCA jack will fit at the other end. That is easy to do. which equates to less than 3 milliseconds of error at 1/30 second. and less at higher speeds. st CIRCUIT BOARD B1 made by straightening a NMSC cable strap. The circuit can be constructed on a small board and will fit neatly at one end of the box. you have to remove it later if you want to make a more permanent scale with inked figures. follow this procedure: 7. but perfboard or an etched printed-circuit board are both suitable. The original was constructed on a type of Vector board.'and tape it lightly to the face plate. Then.Here's what the completed Shutter-Speed Tester looks like when assembly is complete. 1 1 Fig. Never expect a shutter to always deliver exactly the set speed. The camera to be tested is placed on top of the enclosure with the back opened and the lens pointing upward. Be sure that the camera focal plane opening is generally centered over the solar cell. Now. except that it should be large 300 Hz enough to allow enough light to reach the cell to provide adequate vertical deflection (Turn page) of the trace. e. You should see a waveform similar to Fig. You can either leave that scale on the scope or remove it. and recheck at the 60 -Hz position.cycles from the line directly into the horizontal. The PACO scope shown here is probably older than most the readers of this magazine. As long as it is within 20 %. Using the Tester Connect the Shutter-Speed Tester to the oscilloscope's vertical -input terminals. frequency -sync circuit. or 5 -cm high and 8-cm wide. 60 -Hz signal to the vertical input. or /10 second. the acceptability tolerance is plus or minus 30% for leaf shutters. Adjust the horizontal vernier control until exactly one cycle is displayed on the oscilloscope face with the retrace line. See Fig.sweep. Continue until you have the lines crossing at the center as in Fig. 10. Change the coarse frequency to the next highest range (e.. 1 180 Hz 120 Hz 360 Hz 240 Hz 420 Hz 480 Hz Fig. If 6 complete cycles are observed. Switch on the calibration voltage. setting on the coarse frequency control. 20 to 120 Hz. Position and aim the lamp so its light passes through the camera with the light. When repositioning it. or connect a lowvoltage. Notice the LINE FREQ. The actual diaphragm opening is unimportant. For focal -plane shutters at over 1/400 second. and read just the Vernier control to obtain the figures shown in Fig.inches high and 3.inches wide. 85 . and label that line as 60. it is plus or minus 35 %. Mark a line on the paper chart. 8. trip the shutter. The waveform will be located somewhere along the time base. 1. 8 -You don't need an exotic oscilloscope with the Shutter -Speed Tester. those latter speeds might lie quite close together. and the point is then marked as 10. but with the horizontal time -base trace at the bottom as well. note the KC markings as opposed to HZ markings on new oscilloscopes.Fig. At the right are three complete 60 -Hz cycles within one scope sweep indicating a time sweep of 1 20 second. camera lens and solar cell opening in alignment. That procedure is actually very simple and in a few tries you'll find it surprisingly easy and fast. Also. if visible. as far as your scope will go. centered. 9. Those will give you the 120 Hz to 480 Hz positions. and make a neatly printed copy. 5. Watching the screen. opposite the knob's pointer line. 1/60 second. 11. 9 -These two waveforms indicate different sweep periods. the sweep frequency is 10 Hz. The time base is now calibrated. That is the 60 -Hz point. 2. 10 -Here are waveforms for ten different frequencies that may be used to calibrate the dial shown in Fig. At the left is a 60 -Hz cycle indicating a 1 60th second sweep. or /120 to 1/480 second. 120 to 1200 Hz). On some oscilloscopes. At high speeds. Mark each in turn on your chart. the dial setting is the actual shutter speed.g. Adjust the controls to provide a trace about 2. Set the lens aperture to its largest opening. 4. Set the oscilloscope sweep speed to less than the shutter speed being tested. adjust the control to a higher sweep speed and trip the shutter again. then for 3 cycles. 4 cycles. or as a shutter speed. That setting puts 60. 2. etc. such as more than /100 second.g. 1. See Fig. use the extremity marks as your guide. Set the coarse horizontal frequency control to its lowest setting. Then. Readjust for exactly two cycles and mark that point 30. 3. That is most important when measuring short shutter speeds. Set the shutter. it is within the accepted standards. That can be due to a weak spring and will produce ghost images on the film with leaf shutters as well as an over-exposed section with focal -plane shutters. the shutter probably needs a disassembly and cleaning. as in Fig. That display occurs when the shutter blades or curtains bounce open again after they have closed. Should they differ. simply check exposure with the slit at each side of the opening at the rear of the camera. Have a technician repair it for you.Here's what the test setup looks like. Orient the slit perpendicular to the direction of curtain travel. solder. J1 etc.effect transistor (FET) 2N3904 NPN transistor CURTAIN TRAVEL 02- RESISTORS (All resistors are 2 -watt.120. Fig. Focal -plane shutters expose film by passing two curtains across the film plane. black cloth or felt. metal strap. do so as a precautionary procedure. When not needed. SHUTTER BOUNCES OPEN 11. Light entering the slit during shutter operation will indicate the average light reaching the film at the position where the slit is located on the focal plane. When the shutter. have an expert carry out more elaborate testing for faults. The 100 -watt bulb should be kept at least 3. and bounces.3300 -ohm R3. uneven exposure on each end of the picture frame may be detected with focal -plane shutters. 86 TIME . WIDE SEMICONDUCTORS D1-Solarvoltaic cell (Radio Shack 276 -124. The film can be loaded in the camera and and the slit can positioned behind the lens' center line. R1. Some shutters will go slow as the camera ages but will otherwise operate properly.1. If you can remove the lens system where a focal -plane shutter is used. wire. the curtains being separated by a space that is inversely proportional to the shutter speed.000 -ohm ' 10 °0 units) ADDITIONAL PARTS AND MATERIALS B1 -volt transistor -radio battery -9 -RCA phono S1 -SPST slide jack switch Foam protector.Megohm R2. 13. shielded phono cord with proper terminators (see text). Another technique is to use excess exposed film that is clear and use an opaquing paint to cover the film except for the slit area. 12 -You will need to make a opaque mask for cameras with a focal -plane shutter. sheet plastic.1000-ohm R4. case. Fig. To accurately test those. or any suitably -sized photovoltaic cell) Q1-2N3819 field. then you can often compensate for the difference between the set and actual speed in your exposure. Use ordinary black photographic paper (comes in every box of print paper) and cut a slit approximately 1 16 -inch wide and about -inch long. R5. one of which is shown here to be a shutter fault. it should be turned off so that the heat form the lamp will not damage the lens system. 1 To check exposure at each extremity of the focal -plane opening. closes. hardware. consider that there are over one hundred parts in the average shutter and do not attempt a repair procedure unless you have the proper tools and training. In a properly operating camera those speeds should be the same. it is necessary to reduce the size of the opening to the solar cell by making a small piece of paper. with a slit of about I /16 -inch wide in it and taping that on top of the cell. The bounce is due to a weak shutter spring and repair should be undertaken by a qualified camera technician. If it isn't erratic. That is evidenced by the small "bubble' at the bottom of the graph display. Troubles You May Detect No matter what trouble you may detect. Fig. As mentioned previously. If the shutter speeds are too slow or erratic.PARTS LIST FOR SHUTTER -SPEED TESTER SLIT-ABOUT 1í16 -IN. One type of display you might see is shown in Fig. it slams up against a stop. (Continued on page 98) 13 -The Shutter -Speed Tester is useful in discovering other interesting operational conditions.inches away from the lens during the actual test. circuit board. 12. If you want to print on single sheets. which precludes underscoring In the beginning The Epson MX -80 printer. Whatever you have has probably given you years of trouble-free service. is written for the graphics mode of the newer MX -80 printers. but lately you find that more and more software can't be used with your printer. it's odds -on that you have either an Epson MX -80 matrix printer or Smith -Corona TP-I. hence the MX -80 featured a Radio Shack graphics mode.By Herb Friedman Make your Budget Printer VALUABLE Add new 01F features and greater flexibility with upgrade kits currently available YOU HAVE BEEN INTO PERSONAL COMPUTING FROM ITS "hobbyist" days. or by modern uses for a personal computer. the most popular computer of its day. which could be used with any computer having a Centronics -compatible parallel printer output. Much of the modern software. or you want to upgrade the computer but find your printer can't quite hack it as an up -to -date printer with the new computer hardware. however. 87 . such as letterhead. was intended primarily for the Radio Shack TRS -80 Model 1. The MX -80 (and its clones such as the Texas Instruments and IBM printers) accommodates only tractor-feed paper. what you have is still functional equipment that's been made obsolete by modern software. and the IBM PC's. Essentially. than Apple computers the graphics will most likely be intended for the graphics capability of the most recent version of the MX-80. TP-2. While the original MX-80 has a host of features such as compressed or enhanced printing it lacks a backspace. or TP-2 PLUS daisy printer. Even if the software is for other Epson's Graftrax -Plus printer upgrade consists of three ROM's secured to a conductive foam strip." some of which are prone to damage the printhead when pushed through the printer mechanism. or have built your system on a tight budget. the Apple l! and 11e. the only way to do it is to use a special plastic tractor/pin feed "carrier. which has the graphics capability for the present most popular 8 -bit computers. For example: The original Epson MX -80 (without Graftrax) does not have IBM compatible dot -addressable graphics. The existing ROM is stored on an empty socket on the board. which by 1985 was selling for as little as $250.The Micro -Grip single -sheet upgrade kit does not interfere with the printer's standard tractor operation. So what we have is a popular tractor-feed matrix printer that needs at least new graphics capability and the ability to feed single sheets. even business stationary-which includes letterheads and envelopes. Thousands upon thousands of personal computer users who could not otherwise possibly afford a letter quality daisy printer struck gold in the TP's-the price might very well be the reason you decided to get a letter quality printer even though you already had a matrix printer. 88 The Fingerprint module plugs into an Epson ROM socket. Let's see what we can do to satisfy those important needs. labels. While some of the retrofits are better or more convenient than you have an original MX -80 printer. The TP-1 was the first under-$1000 Daisy printer. It's safer to pull the plug.) is the Don't follow the Epson instruction to work on the printer with the cover attached. from some of the less expensive (but otherwise excellent) word processors that are available. user-installed retrofit kits are available that will upgrade either printer to accommodate modern needs. which is logical because it is really the printer mechanism from a typewriter. and a daisy printer that needs a tractor feed in order to accommodate continuous forms. you would see only two (not three) ROM's in this view of the base. But today. much modem software is intended for continuous forms printing. Then came the wheel The "letter quality" Smith -Corona daisy printer TP family "buy of buys" when it comes to letter-quality printers for home -and-family and small businesses. IRS schedules. To insure precise alignment of the printing. continuous forms must be tractor or pin fed. The problem with the TP's is that they were intended for single -sheet documents such as business letters. (If a type 251 ribbon is used-which was not mentioned in the early documentation -the TP-1 can produce "camera ready" print quality the equal of machines costing well over $1000 because it is essentially the printer end of a Smith -Corona electronic typewriter with an accessory interface for computer output. If .. etc. such as checks. Retrofit kits Regardless of why you purchased the MX -80 or TP-I in the first place. which gives your old model MX-80 the advanced features of the latest model. 2 FINGER PRINT ems . itallics printing. It was terrible backspacing because the printhead returned to the extreme left and then advanced for each backspace. Among other things.wca." 3 4 S 6 7 8 9 10 Compressed Double -wide Emphasized Double. Mark the orientation of the connector with a pencil or pen and then The removal of this collar from the MX -80 begins the simple process of the Micro-Grip single-sheet feed modification. the Graftrax upgrade provided for dot -addressable graphics. The first of the user-installed MX -80 retrofits was Epson's own Graftrax. Here. others... or _- if -esses.compatible graphics (no more Radio Shack Model I graphics). Note the two rollers being added to the bar that held the paper rollers. (A continuous underscore is formed simultaneously with the character: the head does not backspace for the underscore.with -Graftrax printer manual -which explains all the "bells and whistles. it has you delicately balancing the cover on its end.. Unfortunately. The adhesive Mylar label you fix to the front panel of your printer lists the new functions provided by the modification. which consisted of three ROM's.-NM . two of which plugged into empty sockets in the base of the printer while the third replaced an existing ROM. Among the Graftrax -Plus highlights are the Apple. a graphic printout would cycle the head continuously until the drive motor could be heard slowing to a crawl. The latest retrofit available from Epson dealers is Graftrax Plus.) The Graftrax -Plus retrofit kit consists of three ROM's and the latest Epson. backspacing. a "fine print" that can be used for superscripts and subscripts: automatic perforation skipover (no more program listings printing on the perforations): and a continuous underscore that can be turned on and off from within a program or word processor. the Micro-Grip modification is continued. " The Graftrax -Plus retrofit has the same kind of installation as for the original Graftrax upgrade plug the ROM's into the correct sockets..strike Perforation salaam Lett margin Indent 8 Lines /Inch italics fine print printers comes complete with the main section assembled. and even more important. a true backspace that puts graphic printouts in high gear and relieves the strain on the printer's printhead-drive motor.I BEEPS . just 91 ... etc. kerning.. we know those discussed here will really work exactly as promised because we actually tried them out. but it was adequate for general word processing: underscore. One "caveat" however: The Epson instructions leave the top of the printer attached when you open the printer by separating the top and bottom. If you look closely you'll see the wires to the switches in the cover are attached through a connector.i." $ The passive tractor -feed upgrade kit for the Smith -Corona ' led Wooloo mode FUNCTION Reset . run the test. but it does permit single sheets to be fed directly through the printer without the need for a plastic carrier. Box 609. which allows the three printer control pushbuttons to also program ten operating modes: compressed print: double -wide. Fingerprint is supplied on a small printed.92 In this view the pressure roller is attached to the paper bail and single-sheet retrofit tc the MX -80 is finished. but you can go one step farther and add a real single -sheet feed by installing a Micro -Grip Friction Feed (Bill Cole Enterprises. CA 91740). The Fingerprint also can be installed in an IBM Graphics printer because the IBM Graphics Printer is MX -80 Gra(trax based (cloned)! As long as you have the printer open consider a retrofit called Fingerprint (Dresselhaus Computer Products. separate the connector and put the cover in a safe place until you're finished. The Micro -Grip retrofit does not interfere with the tractor operation. Fingerprint bonus retrofits.circuit board that swaps for the ROM in a socket 113. it can be removed in seconds. The Micro -Grip kit consists of three components: two rubber rollers that replace the existing Epson paper guide roller (which is sandwiched between the two tractor pin feed mechanisms). and fine print. MA 02170). The mechanism for the TP -1 printer retrofit appears to be permanently installed. and a rubber -roller pressure assembly that clamps to printer's paper bail -the bar that holds the paper down for printing. Glendora. When the job is done. Wollaston. 837 E. For example. you cannot detach the TP -1 casing top when making the modification. Instead of substituting for the ROM in socket IB. and with virtually no extra effort required on your part. . however. emphasized. You clip two attached Fingerprint leads where indicated and you now have both the Grgftrax and the Fingerprint Sheet feed If you quit now you'll have one heck of a matrix printer. Note that the pin -feed mechanism is against the paper sides. ( Continued on page 102) Because the leads to the fan assembly are too short. double strike: perforation skipover. install the Graftrax ROM in the Fingerprint socket and then snap the Fingerprint assembly into socket IB. the one that's replaced in the Graftrar retrofit. and the feed is straight. Alosta Ave. itallics. left margin indent: 8 lines /inch spacing. just touch the printer's ON-LINE button twice and the printer shifts to compressed type without any commands from the computer.. 85. cracked windows. runway conditions.1 MHz.85 MHz.5 MHz.9 MHz. and advice on ground facilities (fuel.8 and 132 MHz. hot -air balloons. The FCC doesn't want the Aviation Radio Service to turn into yet another CB -like service. You'll also find it interesting to listen in on the frequencies selected by pilots to chit -chat with one another. . you're missing plenty! For example: The airlines have certain frequencies in that band which they use for air /ground communications relating to equipment problems and various other complaints.0 MHz. There are also control towers. airline pilots can often be heard chatting merrily away on 123. The fact is that the VHF aero band has plenty to say for itself. that band is either overlooked or ignored in favor of the standard VHF and high /low UHF bands. rental cars. which isn't exactly a control tower but can be used by the pilots to obtain information on wind direction. although some landing areas may (instead) use 122. Unfortunately. and 131.725 MHz.9 MHz. lodging. foul tasting drinking water. Check out the Goodyear Blimp on 132. yet.8 MHz.9 MHz. the FCC. and 122. ground (Continued on page 98) also have 93 . Put your scanner in search mode and seek out more of those frequencies.0 MHz. and broken doors which refuse to remain open or closed. limos. Other frequencies that have produced similar communications include 129. food. many small rural landing areas have no communications facilities at all. food delivery. Not all airports have FAA control towers. which permit tuning in of police and fire communications. races. pilots of radio -equipped aircraft will normally transmit their intentions "in the blind" on 122. be aware that there are all sorts of other airline company communications between 128. ultralights.8 and 132 MHz which relate to gate assignments.75. or electronic systems. which have neither a control tower nor a Unicom. In fact. Best action occurs on sunny weekends.3 and 123. While the specific frequency varies from airline company to company (they aren't the same in every area). Private pilots like to chat on 122. while passengers are relaxing with a cocktail and watch a film.85.ON SCANNERS A Pull in MANY By Mark Saxon all that aero-action that's on the air! MODERN SCANNERS COVER THE VHF aero band.95 MHz) which private pilots use to There's More! Some of the off-beat and unusual aviation activities that take place are worthy of monitoring. you might try checking out 129.7 or 123. all too often. gliders. and you'll have to select those which contain the pilot write -ups. although they can often also be heard on 123. If you have the ability to scan those frequencies and aren't doing so." and those write -ups include various flashing red lights warning of malfunctions in hydraulic. because they reveal a batch of rather hair-raising mechanical problems taking place. like the poor soul who discovered that he had left his briefcase containing negotiable bonds in an airport rest room (no worse than the lady who did the same with her diamond ring)! Frequencies used for write -ups all lie within the sub-band running between 128.4. and even food.05 MHz.025 and 123. TWA problems have been noted on 131. Chances are that they are not especially interested in the public's listening in on those conversations. lems go out on 130. parachutists.475. 122. Many smaller airfields catering to private pilots do have a communications facility known as Unicom. 130. sailplanes. But. American Airlines uses that frequency in many areas. Pan American's prob- Private aircraft pilots can often be heard chatting on 122. Larger airports with a control tower a Unicom channel (usually 122. Helicopters are most active on 123.45 MHz. such as air shows. Write Ups The pilots call those problems "write ups. electrical. A great many of the problems are noted as being repeat items which had been reported many times previously. although the FCC has issued a number of stern warn- ings against the practice. the pilot reports non -working toilets ( "heads "). although the frequency is supposed to be used for other types of communication. At other airports.05 MHz. much to the FCC's dismay. 122. ground transportation) available. hang gliders. which runs between 118 and 136 MHz. fly ins.075 MHz. Sometimes. etc. although those conversations are also frowned upon by temporary control towers at air shows are usually established on 123. etc. and order taxis. Many of those activities can be monitored on 123. The majority of Unicoms at small fields operate on 122.75. and 122.25 MHz at times. Those aero frequencies are also used for passenger complaints. 20 -msec. The Shugart SA200 drive.storage system can be upgraded with a disk drive! The way some advertisements tell it.. Those drives were kicking around the surplus marketplace at $125 when Radio Shack's own drives were going for well over $200. or both. On the other hand. have different electrical connections. the newer models. the Montezuma Micro CP /M 2. While it is true that there are some outstanding values in disk drives. fits the specifications. most Radio Shack computers.By Herb Friedman ON COMPUTERS 1 J J Inside facts on inexpensive disk drives INSTANT ACCESS! RANDOM FILES! FOR almost pocket change. 94 . your computer's cassette data . expensive hardware unless they keep on reading. Also. 51/4drives which sold for $300 as recently as two years ago are advertised for under $100. everyone can now afford a disk drive.sided. But it is possible for the computer's DOS to allow the user to work around the disk drive's track capability and access time. Several computer manufacturers purchase the same basic mechanical mechanism that's used by other manufacturers and add their own electronics board. to 6 msec. Track access -which is called step rate. etc. 40. step rate. Of all the characteristics. and some of you will undoubtedly come out way ahead of the game. while $200 disk -drive cabinetswhich include the power supply -can now be purchased for well under $100. For example. cann use an SA-200 drive or its equivalent. the same as IBM and Zenith. all commonly-used modern computers use a drive with much step rate. A great buy in an IBM -compatible drive is worthless for. say. which can now be purchased for under $100. spelled out in an advertisement. you can install a faster drive having more track capacity than required by the computer. nothing is ever as good as it first appears. and any access time from 30 msec. many users installed the Siemans model 100 -5B. A computer designed for 40 tracks. Although modern drives have faster track access. For example. At this point am sure that some of readers have reached a state of high du(Continued on page 97) 1 This Shugart SA -400 floppy -disc drive provided the standard for the disc drives used by most popular computers -IBM PC's. and Heath Zeniths. Radio Shack's newer computers uses 40track drives. IBM. IBM clones and Heath /Zeniths can use the same 51/4-in. on Osborne computer. generally 6 msec. For example. if ever. TRS -80's. which at first glance appear similar to the ones used by Radio Shack. 20 msec. or 6 msec.track. while drive B: is 40 tracks. the SA -400 can still be used with many of the new and older computers provided the DOS accommodates 30 millisecond access. Then there are a computer's internal functional differences that are rarely. much of the budget -priced disk hardware cannot be used with many comparmonly-used personal computers ticular.2 for the TRS -80 Model 4 computer can be configured to recognize any individual drive characteristic. As with all other things in life. For example. disk drives because the electrical connections are the same. Drive A: might be 40 tracks single -sided double -density with 6 msec. the TRS -80 model I computer uses a 35 track drive with a 30 mSec. The reason the SA-200 is so cheap is because it really shouldn't or can't be used with the modern computers. Osborne and Kaypro drives. -in There is a difference! First things first: not all disk drives that look alike are alike. step rate. NEWDOS allows the use of any track density from 35 to 80 tracks per side. it is step -rate time that is the most limiting. double. Install an otherwise compatible disk drive in a computer and a relatively slow access time can make the drive invisible to the DOS (disk operating system): You attempt to read or write to the disk and the computer tells you that the drive doesn't exist. which is not compatible with other equipment. double -density. Similarly. drive in a TRS -80 Model I. A goodly number of electronics hobbyists are going to end up with useless. percent shorter than the usual 40 -meter vertical. The W3FQ. IA). mono -band beams and in center. therefore.and 160. esthetics. and the pipes. A QUARTER-WAVE VERTICAI. Dutifully. cost. land. A significant reduction in height is possible with a helical vertical. (Note: Plumbers are concerned about inside diameters. thus loading the coil.4 ratio over the entire 40-meter band.frequency bands-40 -. theory tells us that approximately a half-wavelength of antenna wire is needed to construct quarter wave helical. Wind the Wire In IA finding a helix. This technique is used to 1-1/2 10 Fig. those pipes are specified in that way by plumbing supply centers.meters.By Ed Noll. Two trying problems of the helical vertical are very low impedance and limited bandwidth. it is on those bands that the vertical performs at its best. Those can be laid upon the surface of the ground or buried about I -inch beneath ground. I started out with (Continued on page 105) . That may be the new wave in low-band antenna installations. In B.and 2 -inch ID telescoping PVC piping mast. and other drawbacks exist. The antenna is 40. 1 -The basic helical winding is shown in A. the turns are closer together in the center.space. because of the required height for operation on the lower.) Spirals are not spaced uniformly but are crowded in the central region as per Fig. largediameter spiral that is wound on a -1/2. IS A SLAT package and adaptable for installation on a small lot.loaded. One innovation is the wide. Ironically.140 -meter helical vertical (antenna) combines a number of ideas that result in an SWR no higher than a 1. installation difficulties. 2 -All you need to know about erecting a back -yard helical 40 -meter vertical antenna. Four resonant radials are helpful. IB.mobile verticals. 80. -- METAL 2 FENCE 2' POST improve operation as do the coil insertions in shortened. No tuner is required. B 17 12 27 12 27 12 37 12 10T 12 10T 12 10T 12 INCHES 10T 12 18" 20 2 1 A W3F0J ID 127 20 107 THRU.80LT AND GROUND TERMINAL __ 8T 24 67 24 EYE -RING BOLTS T COAX 17 Nts* 32 RADIALS GROUND LEVEL Fig. Note that spacings are equal between each turn. However. The basic helical vertical consists of a uniform spiral or helix of antenna wire wound on an appropriate mast (Fig. That configuration will yield accuracies in the 5 -digit area. That is. If you don't have a good DMM. Nixie tube voltmeters by HP. may have closely matched resistors with tolerances in the . split -piece headband that mounts securely on the head for a comfortable.CROSS MATCH ONE (Continued from page 46) which are virtually worthless pieces of junk. Also. and which has sufficient resolution. If all else fails. Connect the speaker ground and the powersupply ground together at pin 2. there's still another option. Generally. However if you're just after selecting 1% units from 5% and 10% units.emitting diode. relative to the reference used. And the third sample should be within accepted tolerance.025% specs will get the job done. 9600 Aldrich Aveue South. NEW PRODUCTS (Continued from page 20) frequency response curve fora variety of applications. However. In any case. Another possibility is to use a Deca potentiometer or resistor substitution box for RSAMPLE. that method should be used only as a last resort. the respective light. It would be a good idea to test the audio output with the speaker output muffled by pillows. Minneapolis.recognition.000 -ohm or higher having . LOW -POWER AUDIO AMP (Continued from page 36) The parts for the Low -Power Audio Amplifier are arranged on a solderless breadboard as shown in Fig. You may want to glue the perf-board to the bottom of the case. So. However. MN 55420. or better. On the other hand. connect the input -signal ground and the negative terminal of C2 together at pin 3-that is the input -signal ground terminal. use old wire -wound resistors for RI and R2.5 %. using a Deca potentiometer or resistance substitution box for RREF will allow you to determine the RsAMPLF's value. use the one on display down at your local parts supplier. you'd dial up the desired value you want to substitute across the RSAMPLE terminals while measuring the potentiometer with a suitable multimeter. . where values from 2000 ohms to 100. 2. under. Fluke. Telex Professional Audio Department.lasting comfort while averting fatigue. Any DMM with 5 times the accuracy you want to get out of your finished project. To insure good stability. keep the input and output signal lines separated.neighbor feelings. write to Telex Communications. assuming you don't want to use the three-resistor test and don't have access to either a Deca potentiometer or resistance substitution box. One sample should be over accepted tolerance. That is most easily accomplished by the use of three known sample resistors and one reference resistor. and intolerance conditions. . They have the best temperature coefficients and less drift over both time and temperature.01% range. will work nicely. That configuration will allow you to not only look at over. That setup will both calibrate and check out the Cross Match One. Slip proof foam temple cushions provide long.microphone distance and the option of wearing the mike on the right or the left side of the head. because of battery drain and /or destructive current drawn. Siren sounds do not promote good. Very small resistance values cannot be measured. A reversible swivel -mount and 180° adjustable boom provide a custom fit for proper mouth -to.01% to . For best performance.e. i. range. computer speech. that's only the tip of the iceberg. One sample should be under accepted tolerance. The amplifier was so wired that it could share a Global Specialty's breadhoard with the Yelping Siren. R3. But. you can always resort to using a 10 -turn potentiometer for RSAMPLE and a precision resistor for RREP when adjusting tolerance. if you have a precision substitution box that will handle it. The PH2O has a stable. etc. 1%.1% range. Danna. 2). auction. Telephone: 612/884 -4051. especially where resistors are being matched for instrumentation amplifiers. which determines tolerance limits. you can probably do with less accuracy and a less than ideal match. you can fine -tune gain as desired. PA systems.emitting diode should light when each is placed in the RSAMPLE position relative to the resistor placed in the RREF position. If the potentiometer isn't stable enough. where you simply dial up the resistance that lights the IN tolerance light.matched resistors in all kinds of otherwise useless surplus. The absolute values of the above resistors are not as important as the ratios between them. by adjusting gain of the op -amp. and the like are another source of resistors. 96 In any case. try a fixed resistor and trimmer in series. including music. In that configuration. that should present no problem for most applications.1%. especially for small resistance values. Set Up and Application The gain adjustment (BALANCE) potentiometer. For more detailed information. . need only be set once for a given What looks like an exploded view is the Cross Match One just before assembly into its plastic case. but also where the skirts of in -over curves and in -under curves overlap (see Fig.. All resistors should be connected directly to the fiveway binding posts to avoid lead resistance errors. and audio -visual applications. you can find close tolerance or well. when matching resistors in the . and you need a good DMM around 41/2 digits. under 2000 -ohms.000 -ohms are typical. dependable fit. any resistors around 10. The surplus market is awash with half-height disk drives: the same kind or size used in the Regardless who made the drive. Use the convenient order coupon below. You are. But what if you want to add two disk drives? Do you need two power supplies with cabinets? Not any more. a separate power supply must be provided for the extra drive(s)." because there is not precise metric equivalent for inches! form below. Send me the next eight issues of Hands -on Electronics for $19. In addition.supply prices are still back in the stone age of personal computing -somewhere around $150 for a single -drive power supply and a cabinet.S. In each instance. If you want the next eight issues.00 per copy. or an Apple disk in an Atari. or one that will be installed in the empty space provided for a second drive.00 postage and handling for U. Likewise. the metric equivalents from Europe don't quite fit the American -made connectors. That's where there is compatibility that translates into BIG BUCKS when you need ail extra drive. BCB and shortwave receivers.50 plus $1.FRIEDMAN ON COMPUTERS (Continued from page 94) dgeon and can't wait to take pen in hand to protest that data disks from an IBM are not compatible with Radio Shack. YOU CAN HAVE THE NEXT FOUR ISSUES of Hands -on Electronics delivered directly to your home for only 510 00. the TRS -80 Model 4 can accommodate two additional drives. Software Support will sell you a standard cabinet with a dual power supply (for two half-height drives).00. That is the kind of driver you would use to physically replace an existing drive. Canada and Mexico $1. U.00 starting with #5. or any disk into any other computer unless you use some kind of software that interprets the electrical format of the disk to what's required by the host computer Even then. the IBM PC can accommodate two additional external floppy dri tes through the signal connector on the back of the disk -controller card. Send me copies of Hands -on Electronics #4 at $2. Often. The problem of power comes in when you want to add a drive not originally provided. In either event. GET IN ON THE ACTION! Order your next issue of Hands-on Electronics today. no power is available from the computer itself. Foreign add $7. Get every issue! Commodore. the power connector is the same. Apple. However.00. You can expect top-notch digital projects. feature articles on electronics fundamentals. you can order your next copy of Hands -on Electronics now. About $50 is what it's worth. SUBSCRIBE TODAY! Use the order When no provision Is made So far we have only mentioned the bare drive. (Name) Detach and mail today to: HANDS -ON ELECTRONICS SUBSCRIPTION DEPT. test equipment and tools will round out each issue. etc. Send me the next four issues of Hands -on Electronics for $10. I am talking about the disk drive itself. you can even save a dollar off the newsstand price Get eight issues for $19 00 IF YOU'RE THE KIND OF READER that doesn't want to wait. Neither the components nor the cabinet are worth that kind of money. darkroom gadgets. Of course. P. you'll see that some power. Postage is free in U. The same is true for Atari and latest computers. Inc. low cost 51/4-in. If you need two external drives you can go the halfheight route. Fraingham. photographic.00: starting with #5.00 I want to be sure I don't miss any issues and want to save $1. valuable add -on computer projects. For example. BOX 338 MOUNT MORRIS. IL 61054 (Street Address) L (City) (State) (Zip) J 97 . disk -drive suppliers such as Software Support. correct. fun -to -play electronic games. the savings from doing it yourself is more than 50% of what the job would cost at an authorized shop or distributor. Actually. and for an extra $15 ($65 total cost). For Canada add $4. Presently. Allow 6 -8 weeks for the Please print first issue to arrive. or a replacement. or course.S.O. If you look through advertisements for disk -drive hardware.S. however.. Radio Shack TRS -80. For Canada add $2. some formats simply cannot be converted: You cannot convert Apple discs to a different computer unless the host computer actually contains an Apple emulator. Foreign add $14. (One Edgell Road. Postage is free in U. you will use the power connections already built into the computer. a drive that does not have its own power source. devices to improve your car's performance.S. TO HELP YOU TO BE SURE that you don't miss any future issues of Hands -on Elec- tronics. bare replacement or complete (with power supply and cabinet) disk drives are available for the most popular computers: IBM compatibles and clones. virtually every manufacturer has a proprietary method for recording the electrical signals on the disk. and T199/4A.00 too. It's the "old metric -error problem. test equipment ideas. Hands -on Electronics is crammed full of electronic projects that you won't be able to wait to build for yourself. Software support charges only $45 for a standard -size cabinet and power supply. That is why you can't pop a Kaypro disk in an TRS -80 Model 4. Except for the 99. funds only. and that's what you'll pay at one of the direct -mail. Hands -on Electronics will continue to provide new product and literature listings to keep you up to date on the latest developments in electronic technology. Be sure to send check or money order -no cash! 1 Hands -on Electronics SUBSCRIPTION _1 I want to be sure I don't miss any issues. and more in every issue of Hands -on Electronics.SUBSCRIPTIONS ARE NOW AVAILABLE! EVERY ISSUE OF Hands -on Electronics will continue to contain a variety of construction articles to suit every taste. But I am not talking about data disks: only about the disk drive itself. We pay the postage. But I am not talking about data or program disks.00. MA 01701).9 IBM -compatibles and clones. Two half-heights have the same space requirement as a conventional full -size disk drive. 05 MHz is dead giveaway.50 MHz. New satellites will make increasing use of modular construction. it was a successful step. and measure the framing speed. to vent its exhaust gas away from the rest of the satellite's instruments. those stations can often be overheard on 135. swap the modules in space. Eventually. the projector should be serviced. reports hearing "unusual" communications on 167. using clips instead of screws to reconnect the severed wires. If the camera is equipped to run at more than one speed. listen to that agency on 460. and then repair the module in a more conventional environment. all while wearing bulky spacesuit gloves. and 460. interchangable modules may be mass-produced and carried as part of an on -going inventory. Nelson and Von Hoften made their way out of the ship and into the cargo bay. small photovoltaic cell about a half-inch square.425. The failed circuitry can then be returned to earth. Replacing the Coronagraph/Polarimeter electronics was supposed to be a lengthy task. TX. Now. "Foxtrot 7" is Norfolk VA. Carefully insulate the cell so it will not ground on metal parts and place it behind the lens in the film gate. With the latter. A complete updated directory of all VHF aero frequencies and stations in the USA and Canada.picture camera. The unit can then be repaired and used on another satellite. 460. The Future The success of the Solar Max repair mission signaled the SHUTTER SPEED TESTER (Continued from page 86) That may be caused by unequal spring tensions on the curtain rollers and should be adjusted by a technician. the service technician of the future may be able to select an appropriate module out of inventory. including the airlines. and so on. P..d to vary. approach and departure stations. and one that showed that such repair missions are both possible and practical.O. That frequency is used in all areas. who asks that we not use his name here. passes along the information that 156. and commercial airports. That is the FCC's frequency and "Lima 6" is the ID they use in Dallas. use the same procedure for each. He says that he has seen their units in operation. used to measure the X -ray emission from solar flares. It's a large. To those leads. You might even hear the FAA's special "Flight Check" aircraft. 167. but can't seem to get a handle on the frequencies they use. where they immediately went to work. And what about some photos of your monitoring stations? . in front of the projector's lens.00 MHz. lens onto the photocell.95 (plus $1 postage to addresses in USA /Canada /APO /FPO). the light passes through the SAXON ON SCANNERS (Continued from page 93) control stations. Charles Hallinger.85 MHz (alternate 135. who hails from California. the job entailed pulling back a panel covering the box. you would also use more film. failed satellite -based systems can be successfully repaired. however. expect more and more modular satellites. read the framing speed directly from your chart. It includes all military. and troubleshooting using conventional techniques can be done on the unit. which test the accuracy of the electronic navigation systems at major airports. 142. FAA Air Route Traffic Control Centers. When modular construction techniques. plus airports not open to the public. If you are going there for a visit.25. Set the lens for wide -open aperture and point it toward a bright light." He asks if we can figure out what that was. O. pre-flight estimates had pegged the repair time at three hours. Creighton of Atlantic City. adjust the oscilloscope's horizontal vernier control to obtain a one -cycle square wave on the screen. That will make it possible to replace faulty satellite circuitry with relative ease. Then. The Solar Max mission was but a first. Gilmartin of Illinois writes to ask if we can supply him with information on the communications frequencies used by the Federal Emergency Management Agency. and you may well hear what you're seeking.975. A reader in Dallas. Let's have more reader letters. For instance. Amplification is not needed as the f-stop is usually quite large. but possibly underexposed. Listen in on 142.called "tactical" identifications. or the Shutter-Speed Tester's solar cell.SPACE TECHNICIANS (Continued from page 26) After donning spacesuits. With the camera operating. with leads soldered to it. If the camera speed is fast.625 MHz is a frequency used for op- erations and general communications connected with offshore powerboat races. Perhaps key to the future of space repair will be the concept of modular construction. new book is $10.35. weather. When a circuit fails. Commack NY 11725. Should the framing speed of the camera be slow. pictures could be blurred or jerky and overexposed. If film in the projector causes the framing spe. 142. "Romeo 5" is New Orleans. took about 45 minutes and went smoothly. and cutting a number of wires. as well as the techniques used to repair satellite modules are perfected. Those stations were using coded identifications such as "Lima 65. The final step in the repair of the satellite was the installation of a baffle cover over an instrument called an X -ray Polychromator. Order it from CRB Research. and 143. add a shielded lead to make a direct connection to the vertical input terminals of your oscilloscope. the pictures may be fine.N. 120 -page directory which gives you thousands upon thousands of listings and is the most comprehensive directory ofits kind ever assembled.475. FAA Flight Service Stations. replacing the faulty Attitude Control Module. Normally it's almost impossible to pinpoint so. All went much smoother than expected. in less than an hour. and satellites can be realistically returned to service. the Attitude Control Module retrieved in the Solar Max mission can be repaired and used again. providing sufficient voltage to deflect the trace on the oscilloscope. BOX 56 -GP. Projectors may be checked similarly. for instance "Charlie 2" is Kansas City MO. is called Air -Scan (4th Edition). "Whiskey 6" is New York. Merely hold the movable photocell. and Nelson completed the job. But most important. NJ. Each local office has a similar coded ID. After all. such as that used in the multi mission modular spacecraft base. cutting and taping back a layer of insulation. halting step. you will need an additional. Do that with and without film in the projector. Their main task. private. notes that the State of New Jersey has a special task force that keeps tabs on all of the gambling casinos in Atlantic City. Mailbag Will J.05 MHz. however. When the shutter is operated.95 MHz). That 98 dawn of a new era in the repair of electronic instruments. Testing Motion Picture Equipment To check a motion. and all sorts of other interesting stations to monitor. with the lamp on. removing some two dozen screws. U2. ports Don't miss out again! Send away today for your 36-page booklet containing a complete reprint of all seven articles in the series on Backyard Satellite TV Receivers by Robert B Cooper. use an oscilloscope to follow the data through U2. but yield an extremely limited distance of operation for the transmitter. The next step is to substitute a visible red LED for one of the infrared LED's. 000 THE FRONT END is critical when you build your own system We help you explore several different approaches to making one RECEIVER -SYSTEM hardware. Each line should be at approximately 8 volts with no switch depressed.impedance input voltmeter. Q5. Most mail order outfits have minimum-order dollar amounts. It is best to stay away from factory seconds and grab -bag specials. The meter should read approximately 8. Jr This all -inclusive report give syou all the data you need to build your own Backyard Satellite TV Receiver TELLS ALL ABOUT domestic satellite nntumcations. and how n goes together to bring you direct In your own - fromsatelhte TV reception home order your copy Complete coupon and enclose it with your check or money order for $7 00. can meet them Find out what reechanical and electronics skills you need RECEIVER CHARACTERISTICS. If your unit doesn't work. You might have to look in several catalogs or make a few phone calls. technical details and specifications. Mellen turate! Al. connect a 9 -volt battery to the circuit. and how you the home constructor. the odds are that there is either a malfunction in the receiver or a compatibility problem.3 volts if diode DI is good. : 'yourself' Antenna Includes for RF Converter Own Build Your l» to ask. Q5. (U.. depending upon the function selected. Also check pin 16 of Ul and pin 14 of U2 with a high -impedance input voltmeter. will be the most difficult part to locate. technical Radio Electronics SAVES BABIES HELP EDITION NDEp 1985 and EXPA NEWLY Rotator display wit Testing SATELLITE TV RECEIVER specifications. a shorted or leaky transistor is the probable cause.of Dimes . U2. and all diodes and capacitors are properly installed. and Q6 is in order. plus S1 00 for postage and handling We will ship your reprint within 6 weeks of receipt of your order All others add $4 00 for postage New York State residents must add 58C sales To tax Satellite TV Reprints 45 East 17th Street New York. If no scope is available. S. broadcast eulìa Save Dollars l se it . If the LED produces no light.INFRARED REMOTE CONTROL (Continued from page 55) LED's are more efficient than others and some collimate the light where a wide angle of dispersion would be desirable here. dir and.. If a line is low.0 1 ICeyl L 99 . first check the polarity of the LEDI and LED2 to make sure that they were installed properly. make sure that the transistors have no leakage when no base current is applied. with the other components you might need. N Y 10003 each.converter box by making the appropriate switch closures. A leaky transistor will drain the battery or disable the key matrix.. which generates little advertising by distributors. Not so much from an availability standpoint. If you do substitute here. You should be able to start sending commands immediately with your Infrared R/C Transmitter to your television set or channel. Radio- Electronics w Once all parts are soldered into place and you have made sure that Ul. along with examples of actual receivers built at comparatively low cost and exactly how ANTENNA DESIGN you can build a spherical antenna. check each row and column input on U I with a high. If that test passes. but due to current slack demand by hobbyists. if possible. it would still be courteous to check the cable company's policies before using that device. and Q6 to determine the problem. Bus All switch closures should generate either a short or continuous burst of light. . If your unit still fails to work. substitution of U1. and generates no interfering or detectable signals. Integrated circuit UI.e . Although the Infrared R/C Transmitter project described in this article requires no connection or modification to the cable channel converter box. instead of solid-s buying the common parts first. so it would be wise to find SPECIAL REPRINT the chip first and then make up the BUILD A BACKYARD difference. Total component cost for the Infrared R/C Transmitter can be kept around twenty dollars. the MC14457.. I found one in a mail -order catalog for under five dollars and received it in ten days. with full details on how you can pull those elusive TV signals horn space March ottp .. t EGAL REQUIREMENTS.. Even some visible -red LED's emit sufficient energy for testing purposes.oev. One final note to the builder. The transistors used in this design are readily available and are conservatively rated for this application. A look at. and Canada only) FIGHT BIRTH DEFECTS that will work for you n. While keeping total earth -station cost for the complete system under St. depending upon the number of switches the builder wants to use. plus SI for handling -elr 10 b: 8hFrrst Class postage N Y State residents must add have enclosed $ sales tax. NEW IDEAS is packed with 42 practical circuits for the Electronics Experimenter and Project Builder. The only difference is that the output port of the ZX80 has no connection in place of the ZX81's ROMCS line. The interface is designed to work with or without the CMOS RAM addition. you get complete plans for a simple Tesla coil project that can generate 25. and you must include $1 per item for postage and handling. (The article ran a total of 9 pages. $3. That's easily done by simply connecting two disable lines to the 8K CMOS RAM board. If HM6116p-3's are used. which was the forerunner of the ZX81. and much. 160 (Turn buzzer & RED LED on during XMIT & RDAV) POKE 16382. Allow 6 -8 weeks for the material to arrive. South.select signal for the system 8K ROM. "BUT MUST BE CONVERTED FROM ASCII" 1118 1120 1400 1500 1510 1520 1530 1535 1540 PAUSE 100 CLS GOTO 10 CLS PRINT AT 11. test equipment.RD. 1. Funds! (State) (Zip) J . The 8K battery. Back issues describing the circuit are available from: Radio -Electronics Reprint Department. 65 (Turn green LED on and reset UART) CLS GOTO 10 to spend upwards of $600. Each back issue costs $3. Jumper J2 is connected to the RAM side of the broken line and jumper J3 is connected to the pin 21 pad of JU2 on the 8K CMOS RAM board. household. But that can be easily fixed by running a jumper from the pin 23 -b on the ZX80's edge connector to pin 20 of IC2 inside the Sinclair. In addition to the headlight alarm. let me suggest a dumb terminal. That means that the 8K CMOS RAM must be disabled when using addresses 16382 and 16383. and the remote telephone ringer. All other countries: $2. If the 8K CMOS RAM is to be used then D1 must be removed. NY 10003 42 PROJECTS COMPLETE PARTS LISTS ONE -EVENING PROJECTS EASY TO BUILD 100 (Street Address) L (City) All Payment must be in U. You could start the first night building a project that will have others praising what it can do and admiring you for building it. (Dl allows the interface to disable the system ROM whenever addresses above 8K are addressed. There are really so many possible applications for the port.) Of course if you are not using the RAM board. If you haven't come up with a good. a crystal tester. can also be used with this communications port.backed-up CMOS RAM can be used for Sinclair code to ASCII conversion along with the communication control software. First Class postage and handling $1. THERE ARE PROJECTS for everyone -automotive. The Ki5 line between the edge connector and the RAM's on the 8K CMOS RAM board is the only trace that needs to be broken. The communications interface eliminates the need 10 PRINT "TRANSMIT -1 or RECEIVE -2 INPUT A IFA = 2 THEN GOTO 100 20 30 40 50 60 70 80 85 90 100 110 1110 1115 1116 PRINT "TYPE DECIMAL EQUIVALENT TO ASCII CODE" INPUT D POKE 16383.50.50.00 on a dumb terminal that does the same thing.00 for sea mail. New York. That is the chip.000 -volts AC and draw one -inch sparks. the voltage freezer.00 (U. "ERROR OCCURRED DURING SERIAL INPUT" PAUSE 200 POKE 16383.S. 200 Park Ave. The ZX80 computer. a stereo remote control. Please send copies of New Ideas. Jumper J3 is unnecessary if 2716s or 2732s are used. Other interesting projects are: a sound-effects generator. diode Dl is not necessary since the ROMCS signal is already provided. audio and hi -fi. Break the trace that runs from pin 7 of U6 to pin 20 if the ROM inside the ZX80. Then bridge the break with a 680 -ohm resistor. Please print Detach and mail today: HANDS -ON ELECTRONICS Reprint Department (Name) 200 Park Avenue South New York. and Canada only). then jumpers J2 and J3 will not be necessary and should not be connected. 64 (Turn green LED on and RDAV) PRINT "DATA = ".00 for air mail. 64 (Turn green LED on and RDAV) CLS GOTO 10 LET RC1 = PEEK 16383 (Read control port) IF RC1 < = 127 THEN GOTO 1500 (Is data available ?) LET RD = PEEK 16382 (Read in received data) POKE 16383. much more! Each project was selected for its low cost of parts! WANT TO EXPAND your knowledge of electronics? Build gadgets that only you can have on your block? Acquire a library of projects? NEW IDEAS is the gold mine of circuits you should own and read.) If the 8K CMOS RAM is to be used. the jumper connected to that point (pin 21 pad of JU2) should be disconnected. Photocopies of the article are also available at 50¢ per page. D (Transmit Data) POKE 16383. and projects just for fun. Total cost is sum of copy price and First Class postage and handling cost multiplied by number of issues ordered.S. useful task to dedicate your computer. NEW IDEAS -Circuits for Experimenters and Project Builders! Please send one copy of NEW IDEAS at $3.A RS -232 PORT TABLE 3 COMMUNICATION CONTROL SOFTWARE (Continued from page 72) The ZX80 and 8K RAM Addition Another very useful addition to the ZX8I is an 8K batterybacked-up CMOS RAM board that was described in the July and August 1983 issues of Radio -Electronics. You'll also have to modify the circuit board of the ZX80. NY 10003. One for RD cycle and the other for WI cycle. 00.00.11hIR%.. disc) PC TUT17R Our price . disc) ALGEBRA. 4' by Creative Software . $53. $28. Interactive program teaches you how to use your IBM Personal Computer. $43. A typing instruction system in an exciting hi -res game format.. 1 by Eduware .A mailorder source of software for Atari 400. Our price _. and you can. (Apple II.. List $39. 48k 64k....00.95. disc) tutorial covering definitions.95. a flexible and efficient word processor with VICDATA a powerful and sophisticated information storage and retrieval system. disc) r. simulates an actual space -shuttle flight from Earth Liftoff through Orbital Rendezvous and Approach to Alignment Docking with a space station. NY 10003 Number of items ordered Name 1-1 Total Price of Software S Address Sales Tax (NY Slate Residents Must Include) City Shipping ($2.00. (Commodore VIC -20 cartridge) HOUSEHOLD FINANCE DEADLINE by Infocom . List $32. Handles up to 32 independent objects. The island keeps you under surveillance.NO CREDIT CARD OR COD ORDERS .95. skill levels. $34.. In four phases.95.. (IBM P C.95. Plug -in cartridge. PRISONER2 by Interactive Fantasies . $34.. Commodore VIC -20. Vol.00. color grpahics.. $34. (Atari disc) VIC -20 PIPES by Creative Software List $39. Working instruments.00.. List $39. win 48k.95.. You see every- THE MASK OF THE SUN by Ultrasoft Inc ..4 II . Home utility program records and analyzes your monthly income. $300. One false move.. 64k. Our price . $34. Escape is hardly possible. An ani- ow's mad reign of terror...00.. 48k.. Our price .00.Radio- Electronics Suflwatw StIIIw New for our readers. disc) PRISONER2 by Interactive Fantasies List $39. Use as little pipe as airpossible.95. deciphering new or unfamiliar words. Just try and get out! (Apple II. $69. (Apple II. Our price ..00 per item) TOTAL ENCLOSED (Sorry. (IBM P C. $43. No COD's) S State 71P SORRY .95. and taking tests (Apple II disc) from moving platforms.. information data banks.00.engine aircraft. 5 skill levels..00..94. Our price . COMMODORE APPLE FLIGHT SIMULATOR by Microsoft . Combines VICPRO. disc) Grvphxa IIL>!. You have 12 hours to solve the mystery.. expenses and budget in 16 categories.00. 48k.00. (Commodore VIC-20 cartridge) ..00. Our price $34. and other personal computer systems. Our price .. 48k. $34. Two levels with 20 rooms each.. Scale ladders. Our price .. Turns your computer into a word processor. (Commodore VIC -20.00.95. disc) PC TUTOR by Comprehensive Software _ List $79. (IBM P C.. $34. List $350. A dead man. $15.. Highly accurate simulation of flight in a single. sets. Our price . disc) MICRO TERMINAL by Microcom .00..95. Atari 800. including hardware and software. Stores hundreds of color pictures. Out the window graphics.. Our price .. List $59. 8k additional memory required) ATARI SUBMARINE COMMANDER by Thorn EMI List 549.. IBM P C.. Our price . Our price .95. Apple IBM PC II.00.lictnn RENDEZVOUS by Eduware List $39. disc) thing on the screen.. List $49.. EASYWRITER II by Information Unlimited . Our price . Our price . disc) SHAMUS by Human Engineered Software . List $39. A mated adventure through a series of hi -res screens. (Atari Cartridge 400 800) 9 APPLE MINER 2049 by MicroLab List $39. List $17.... (Commodore VIC -20 tape cassette) HOME OFFICE by Creative List $29. Our price . Our Software price . An ultimate adventure challenge.. cassette tape. $83. Our price . A locked door. A first year algebra THE GRAPHICS MAGICIAN by Penguin Software ..95.00... etc.. and other personal computers. List $39. Make your own animated graph cs. List $94. Learn to type while battling waves of attacking enemy words.. $43. Our price . jump SAT WORD ATTACK List SKILLS by Eduware $49. 48k. Real time flight conditions. $43.95.00.. color graphics.. A tutorial for mastering vocabulary. List $49. Allows access to remote mainframes and minis.. 48k. (IBM P C.00. number line operations.95.. (Apple II.. Watch out for leaks. 1. Chase into a Uranium mine thru 10 levels of traps and capture Yukon Yohan.95.. $34.. and the killer strikes again. Hi -rez graphics (Apple II. A submarine patrol simulator to hunt and destroy enemy ships.95. $25. There are no imbedded commands. (Apple II. 64k. Connect a pipeline from the water supply tank to every house.00. (IBM P C. disc) MICROCOM MASTERTYPE by Lighting Software .. Only you can stop the Shad- joystick challenge. .. (IBM P C.. disc) -if Radio-Electronics Software Store 2C0 Park Avenue South New York.00. BUDGET PRINTER MADE VALUABLE (Continued from page 92) To install the Micro -Grip retrofit it is necessary to very slightly dismantle the printer's feed mechanism so the rubber rollers can be fitted to the tractor-drive bar (instructions are provided in the kit). the Epson will print on continuous tractor feed forms just as well without the bail. it can be easily removed in seconds. Great Britain. a Protestant station. Some channels to try are 9. very gently. The government operates a foreign-service SW station called the Voice of Indonesia. Guam -Another religious broad- caster. or leave the rollers where they are and pull the paper bail (with its roller) away from the paper. Africa.030 kHz. The tractor feed mechanism. 1430 UTC on 11. Use a fair amount of pressure on the contacts to ensure a good connection. and the whole installation shouldn't take more than 10 or 15 minutes. Morocco.190 and 15. 24 hours a day. Hearing that one is largely a matter of finding the right frequency for prevailing propagation conditions. You must make sure that a good electrical contact is made to the cell's terminals. Just be certain you don't push or bend anything while you are doing the work-do everything very. 1700 UTC on 6.IITP--2 can accommodate either single sheets. 15. but it does. which is available from some (not all) Smith -Corona dealers and the Smith -Corona service centers is a "passive" tractor feed. and the tractor assembly is ready for use. but there are English identifications. separating the back of the casing top from the base will be the most difficult part of the upgrade.110 kHz. Some worth trying for between about 1000 and 1400 UTC include: RRI Jay- . The supplied documentation shows how to install and adjust the tractor mechanism itself. A few times and frequencies: 1300 UTC on 6.millivolts one -time setting should last forever. for they are very thin and fragile -and break easily! A well.725. 0830 UTC on 11. However. With the tractor-mechanism upgrade the TP. The CALIBRATION control. a minor disassembly. 1400 UTC on 9. which also operates from Europe. KTWR can be heard about 0000 UTC on 11. you only gain. Indonesia -That.945 kHz.900. all of a 10 minute job at the very worst. however. There you have it! From here on in. and the least bit of resistance could make a significant difference in your readings.designed cell holder comes in handy here. don't guess -let the Solar-Cell Tester check it out! -a JENSEN ON DXING (continued from page 56) First there is the Voice of America's powerful relay SW stations at Poro and Tinang. to the tip of Sumatra. along with Brazil. In addition. When you see the Micro -Grip installed you won't believe it Slide the supplied gauge (a notched rod) on the drive bar. There also are two active religious SW broadcasters in the Philippines: Radio Ventas. Antigua in the West Indies. Programming is mostly in Japanese. is to be able to put better signals into the farflung corners of the world. and the West Indies.405 kHz. Saipan-KYOI is in the business of bringing American pop music and commercials to Japan by SW. Actually. Brazil and the Philippines. which broadcasts in English at 0800 and 1500 UTC on 11. or tractor-fed forms and labels. A special gauge is provided in the kit for alignment of the tractor mechanism. too. 11. The VOA overseas relay broadcasts come from such places as West Germany.665. you may wish to alter the test voltage to satisfy a particular criterion. which is usually calibrated to 450. As with the Epson retrofits. Botswana and Liberia in Africa. will work. of course. Those RRI stations are favorite targets of DX'ers. The purpose. However. meaning it's really a guide that insures precise registration even though the paper is really driven by the normal platten mechanism-just like a single sheet.790 kHz. tighten two screws. Far East Broadcasting Co..770 kHz.890 kHz. there are home service SW operated by the Radio Republik Indonesia network in more than 40 different cities from Irian Jaya. Greece. We are dealing with a very small voltage here. and 17. and range in terms of reception from the relatively common to the very rare catch. since it is on all the time. Tractor feed SOLAR CELL TESTER (Continued from page 44) lines on the face of the cell are negative and they go to ground. R14. is one of the most active countries on SW. the western half of the island of New Guinea. It is. and the 102 The tractor feed upgrade for the Smith -Corona TP's isn't really a retrofit because it does not really become a permanent part of the printer. 11. Trans -World Radio. care must be taken that excessive pressure isn't applied to the cell at any time. The whole project looks much more difficult than it is. Sri Lanka. To use continuous form tractor paper you simply slide the two rubber rollers to the side and reset the tractors. has a powerful station on that mid Pacific island. tractor-fed sheets. however. sets the test voltage.790 kHz. you lose nothing.955 and 15.240 kHz. a Roman Catholic voice. naturally. °N m 25 ANO pp.191 to 4. ep tH es9 p.C6- °w5'p osee+r`°D.750 and 11. 6. You can try for all three around 1300 UTC.. yOAPO syda. there are local governmental stations-in the U. but the local name has been substituted for the Scottish.NPOOMN`N OPAM t0 EP AP` X. most have never been logged here.co``n.. so keep them coming to Jensen on DX'ing.135. Hm mw. The SW signals of Radio Vila can be heard on about 7.045 kHz.o. 5. Sarawak and Sabah -Those two parts of the nation of Malaysia are physically separated from the mainland Asia portion.000 kHz. AyP . And your questions. cai0 Op ne.046 kHz. Long the best bet for tuning that country has been the National Broadcasting Commission station at Port Moresby. 9. The RFO station here is located at Noumea and operates on both 3.' M 1erMaa-s Ye" ep 7..030 kHz. RRI Palu. kP. Radio Pemerintah Daerah Kabupaten Karo in the provincial town of Kabanjahe now operates on a frequency wandering around 4.545 kHz around 0700 UTC. understandably.ma JEGS'pUa eds dr.e ás lo ' le lo. relies on SW radio to keep its people informed. Vanuatu-That used to be known as New Hebrides. PNG operates a network of stations which provide the DX'er with interesting listening targets. one experienced listener.170 kHz. RRI Ambon. Programming is all in Indonesian. ndread.pM ar".e ticularly when it is programming that fantastic local music! Tune for Tahiti on 15. Share your Pacific catches and other SW loggings with others through this column. RRI Jogjakarta. I'm always interested in knowing what you readers are hearing. 3.poas kN r ED . 103 . an° n "" arm' ele 5e. are always welcome! I'll include as many as I can in future columns. Solomon Islands-The Solomon Islands Broadcasting Service at Honiara is another nice logging for those prowling the SW's for Pacific treasures.759 kHz in the Maori language from about 0700 UTC.S. New Caledonia. mTO saa. That's ELECTRONIC TECHNOLOGY TODAY INC. Radio Malaysia Sarawak has broadcasting stations at Sibu on 5.611 kHz. ret .r. Additionally. 200 Park Avenue South.890 kHz during the morning hours in North America until 1400 UTC.a-- ' .sw vne".355 and 7. or just a bit off 9. New York 10003. Just as an example.845 kHz. Ralph Perry..aa.O. That is a bit too exotic for most North Americans to even try.e o.ng (ISO t or 2 books 30a each acid 50004 TOTAL ENCLOSED Name AOOrese PRICES GOOD UNTIL June 30 Cay Slate 70 HOE S4 It Now you have plenty of Pacific area listening targets for your SW tuning.SNC1 Moce dan ndse JCjOH MICP PpOC ..Another bit of France in the Pacific is New Caledonia. 'Ey 2O c lo ners raa _ aII. Massapequa Park. say 0600 to 0730 sign off. Tahiti -The Radio -TV Francaise d'Outre Mer (RFO) station at Papeete may be just about everyone's favorite Pacific SW outlet. NY 11762 Number of books °reenact r I-1 Total Pnce of BOOKS Sates Tax (NY State Reskienls only) Slopping and HandI. a.960 kHz. 3. Papua New Guinea -That country includes the eastern half of the huge island of New Guinea.ma:' \'aoT.Jees ydn d ee^an a.. plus your photos of your listening post.825 kHz later in the evening. dn .pl.` Ala" o^ Pdje^`e d. plus some off-shore archipelagos. 3. 4.ar. That station transmits on 4.005 kHz and at Kuching on 5. ° .985 kHz. with English news following at 0800 UTC.dr a 1 Im áá¿a9 . Inc. Cook Islands -Radio Cook Islands is another bit of exotica and can be heard on 11. A few are heard occasionally in North America. both being located on the island of Borneo.*^ .c00. That one is an exotic catch that fires the imagination. RRI Timor. or 5. RRI Kendari. P."" eo °. Hands -On Electronics. And they have their own SW stations. Tune for that broadcaster around 0800 to 1200 UTC. New York. who currently lives r aysia-just a stone's throw from Indonesia -reports that one of those stations. par- Electronics Paperback Books NEW Paperbacks You'll Want To Read CHECK OFF THE ONES YOU WANT PN ` .260 kHz from around 0700 to past 0800 UTC.d d e I.e . co"des K. Such a widespread nation.p n4 É.and DX's from Kuala Lumpur in Mal- apura. the equivalent would be at the county level -which number in the hundreds.215 kHz.a1 nn9 p rear u Py PO IN1gOpM w`aPCVéedm ss'd er a" . Sabah's station is Radio Malaysia Kota Kinabalu. and they're worth losing some sleep to hear. Tune 9.020 kHz between about 1000 and 1300 UTC.196 kHz. RRI Jakarta.pe°enee.170 kHz around 0300 UTC: or perhaps on 6. Gernsback Publications.. of course. 4. and RRI Menado. wan 'enn5e'Ra o_ SSpPS.00 eN*0 p\Ueey Bns adder.. Box 240. TINT SCREEN BEHIND ENTIRE AD PLUS ALL BOLD FACE AD: add 45% premium to total price. PA 18977.50) 19 ($23. OH 44094.75) 16 ($20.00. S. 104 Signature IF YOU USE A BOX NUMBER YOU MUST INCLUDE YOUR PERMANENT ADDRESS AND PHONE NUMBER FOR OUR FILES. Box 1376 -2. NY 11235. Dept.. JIM RHODES.e. Plainview. TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD PLUS ALL BOLD FACE AD: add 45% premium to total price. INC. (Please specify. circuit boards! Send stamped envelope: XANDI. PO Box 63 6025. MAC ROCOMA-GH. (Dept. If you wish to use your credit card to pay for your ad fill in the following additional information (Sorry. Movie Channel. East Meadow. Box 130 -F4. Toledo.picking. Hillside.. schematics.000 other scanner owners in the nation's largest not -for-profit association of scanner owners.25 per word prepaid (no charge for zip code).500.50) 23 ($28. Copy to be in our hands on the 15th of the third month preceding the date of the issue. to no. covert sciences. fascinating true stories. prepaid.) Rates indicated are for standard style classified ads only. NON -COMMERCIAL RATE: (for individuals who want to buy or sell a personal item) $1. voice scramblers. Free brochures. CA 95969. Eastlake. put one word on each of the lines below and send this form along with your check to: Hands -on Electronics Classified Ads.00. NY 11554.25) 30 ($37. ( ) Plans Kits ( ) Business Opportunities ( ) For Sale ( ) Education Instruction ( ) Wanted ( ) Satellite Television ( I Special Category: $10. 1025 Ran some Lane. Flushing. ADS SUBMITTED WITHOUT THIS INFORMATION WILL NOT BE ACCEPTED. Any channel 2 through 8: 14(A) through 2211). (i. Pataskala. FOR SALE Secrets -the outlaw publication the ca- CABLE -TV ble companies tried to ban. DYNA. PCB for Satellite Stereo Project in October article is now only $15. Sheungwan.00 projectors.extra -cost insurance coverage. NY 11375. radio broadcasting. D &WR. 5 °0 discount for same ad in 6 issues: 10% discount for same ad in 12 issues within one year: if prepaid. NY 11354.Y. 68 -12 110 Street. add 20% premium to total price TINT SCREEN BEHIND ENTIRE AD: add 25% premium to total price.25) 34 ($42. THE Intelligence Library-Restricted technical information & books on electronic surveillance. Fast service.00 per word. DISPLAY ADS: 1" 2' S135. there is a surcharge of $10. weapons. investigation.. CATV. For special headings. LBT. MENTOR. 1.00 1000. Largest selection available. lock. Box 25647. Sunday or Holiday. (212) 897 -0509. $1. $8.. Send just $9..00 postpaid. August issue copy must be received by May 15th). free classified ad service. 10003 PLEASE INDICATE in which category of classified advertising you wish your ad to appear. BOX ADDRESS WILL NOT BE ACCEPTED UNTIL ADVERTISER SUPPLIES PUBLISHER WITH PERMANENT ADDRESS AND PHONE NUMBER. EXPANDED TYPE AD: 51. N. WI 53201. TI -99 4A software hardware bargains. Entire ad in boldface.00 including disk thousand name brand programs for Apple IBM -PC details RELIANT. Plantation. Results comparable to $2. and other features.monthly publication with tech tips. converters. lowfers. copy of Federal laws $10.00) 29 ($36. etc. Quantity discounts. precision custom wirewounds. date.00 refundable to: JR INDUSTRIES.25) 22 ($27. Send self.. Additional bold face (not available as all caps) 25C per word additional (20% premium). 1 43614. Kingsport.W &!. See below for additional charges for special ads. Route 1R. Eliminate undesirable signals.A.95.75) 24 ($30.. Washington Crossing. scramblers. descramblers. (215) 736-3979.. Do-it-yourself pagers.00) 25 ($31.00 PLEASE PRINT EACH WORD SEPARATELY.) Send $20. SATELLITE -TV receiver breakthrough! Build your own system and save! Instruction manuals. ADVERTISEMENTS USING P.S. unusual kits CAPRI ELECTRONICS. CB. 5834 -B Swancreek. Brooklyn. CABLE FACTS.95. Money back guarantee. 414 Chestnut Lane.25) 18 ($22. FALA ELECTRONICS. sur- veillance. US $8. NY 11803. CATALOG: Hobby. No. no.00. N.. Flushing. When normal closing date falls on Saturday. bugging devices. news of new listening adventures.00) ($26. Margate. ROBERTS. Creditcard orders 24 hours. 200 Park Avenue South. and more. car rier subcarrier detectors. GA 30520. unused. CABLE TV "CYLINDERS" 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ($18. alarms. OH ownership of small electronics manufacturing business. Plus member benefit package including car rental discounts. TN 37660.HANDS -ON MARKETPLACE PLANS AND KITS SATELLITE TELEVISION BUSINESS OPPORTUNITIES PROJECTION TV _Convert your TV to project 7 foot picture. 1 WHOLESALE F -59 cable connector $80.00) 33 ($41. 240 -A Fencl Lane.without investment. Equivalent of cable company "cylinders ". FREE catalog featuring scanner accessories.75) 20 ($25.00 each. 1 SCANNERS MECHANICALLY inclined individuals desiring AZ 85282.85 per word prepaid. 31 We accept MasterCard and Visa for payment of orders. Milwaukee. Write: BUSINESSES. active antennas. HBO.. 1400. Send $2 50 for assembly plans and pricing to KERBER KLOCK KO. Blvd. PO Box 33610. MINIMUM 15 WORDS. CLASSIFIED AD ORDER FORM To run your own classified ad. Huge selection. Box 690 Hicksville. (No refunds or cerdits for typesetting errors can be made unless you clerly print or type your copy. Free MATV catalog. Free catalog. 21 RESISTORS v.00: 3 2' r -5405 00 General Information: Frequency rates and prepayment discounts are available.): Card Number Expiration Date 135 -53 No.75) 28 ($35. Showtime._.device schematics.2W5% 3 cents. Bi.75) SUPER powered notch filters. Paradise.75 for 10 -month trial membership to: SCANNER ASSOCIATION OF NORTH AMERICA. hood locks.Y. TUBES. etc The best selection available. NY 11801. DIGITAL Klock Kit plays -of -12 melodies each quarter hour. more! PANAXIS.00 AUTOMOTIVE SECURITY EQUIPMENT COMPANY. All other items same as for STANDARD COMMERCIAL RATE TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD: add 25% premium to total price. INDIVIDUAL photofact folders. Minimum: 15 words. Box 711 R. Brighton 11th.O.00) 17 ($21. issue closes on preceding working day - . 92 -R. Plans and 8" lens 519. IN BLOCK LETTERS. no minimum. $3. CABLE television. Hard -to -find items. linears.25) 26 ($32. Total cost less than $30. stamped envelope for list. or for rush send 51.00.addressed.50) 35 ($43. Tempe.. converters. Dept.50) 27 ($33. FL 33318. Allow 4 weeks for delivery. Suppliers list included. Hong Kong. Box 17621.Illustrated information free. Z).00: 2 2'4-$270. FL 33063. FREE Automotive Security Catalog.E. glass dectectors.. 21K. 36117 Hil!crest. °rometalfilms. Displays time. ONLY FIRST WORD AND NAME set in bold caps at no extra charge. Transmitters. PO Box 382. no telephone orders can be accepted. OH 43062.50) ($38.. Canon. CLASSIFIED COMMERCIAL RATE: (for firms or individuals offering commercial products or services) 51. ALL COPY SUBJECT TO PUBLISHERS APPROVAL.75) 32 ($44. IL 60162. identification documents. new. JOIN 30. The helical wire is No. and mail to Radio -Electronics.00 order any of the items indicated above. 2 and 4.Electronics back issues (1983) (January. but the length specified above will bring you near resonance should you use my construction data.00 El Special Projects #6 (Spring 1983) Special Projects #7 (Summer 83) NOT AVAILABLE Special Projects #8 (Fall 83) . February 1983 not available) Write in issues desired $3. pages and article desired. check off the ones you want. The final version of the W3FQ.50 Radio -Electronics Annual 1983 $2. 1981 not available) Write in issues desired $3. Include payment in full.00 8-Ball Satellite TV Antenna $12.spaced at top and bottom. VCR Repairs IBM Typewriter to 7 7 7 7 J Computer Interface through -bolts. 200 Park Ave.1 PVC helical is shown in Figs. 105 . NOT AVAILABLE $4. Feb.50 Radio.try final procedure.00 Special Projects #5 (Winter 1983f $4. Note the two termhrals and the coaxial cable connected to them.S.50 $3. air mail) $ Total Enclosed Name Address City State Zip Fig. Two ten foot sections of PVC piping are telescoped together for a distance of 2 feet. notice that the turns are wide. several lifts might be needed to resonate the helical on some preferred frequency. $3.00 Build Your Own Robot TV Descrambler (January... In the initial checks I must have lifted off the mast about fifteen times. #1 April 1908) $4.00 per item $ $ All other countries ($2. That is strictly a cut and.00 per item. New York. South. Final version obtained 40 -meter resonance with approximately 54 feet. plus shipping and handling charge. 200 Park Ave... (Continued on page 106) BOOKSTORE 34. South. & Canada only) (Includes FIRST CLASS POSTAGE) $1. March. Please allow 4 -6 weeks for delivery.00 ' Hands On Electronics #1 RE Annual '85 $2. Inner conductor and braid of the coaxial line are attached to these two terminals as shown in Figs.-W3FOJ helical verical is shown in the author's yard. include your payment.00 per item.00 _7 Radio.00 Low Frequency Receiving Techniques Building and using VLF Antennas New ideas - 42 circuits for experimenters . and start- Radio ed the winding from scratch three times. New York. 4-The botcm of the helical antenna mast is shown here.00 How to Make PC Boards $2.00 . NY 10003.25 Modern Electrics (Vol. Complete the order form below.Electronics back issues (1982) Write in issues desired $4.50 Special Projects (Spring 1981) 34.CALLING ALL HAMS (Continued. Catalog (1918) (176 pp) $6. Two through -bolts and associated nuts are used as the two terminals of the vertical. sea mail) S ($4. That is no big problem because of the wide helical bandwidth and the light weight of the PVC piping.50 $3. For a permanent job you may wish to use epoxy protection and/or VHF sealant tape. Dec. funds Reprint Department. You will be relieved of that initial drudgery.50 '7 Radio. spaced as shown on the right side of the mast.00 Build Your Own Satellite TV Receiver $5.00 All About Kits $2.troni page 95) 65 feet in the first try.S. 3. 2 and 3.00 Special Projects #10 (Spring 84) $3.Electronics back issues (1981) (Jan. Bottom end of spiral wire is attached to one terminal and the four 31foot resonant radials are connected to another. 1.00 Radio. $7. February 1981) $3.. However.50 Special Projects #4 (Summer 1982) $4.50 Radio -Electronics Annual 1984 $2. check or money order (DO NOT SEND CASH).95 Electro Importing Co.00 $3. In winding the helical. NY 10003 $ Total price of order $ Sales Tax (New York State Residents only) Shipping & Handling (U.Electronics back issues (1984) $3. 16 with vinyl insulation. Indicate the issue (month & year). To It you need a copy of an article that is in an issue we indicate is unavailable you can order it directly from us. They are held firmly by two eye -ring Electronics. We charge 50r per page. A total of 13 such bolts are used. ARTICLE YEAR MONTH PAGES TOTAL PAGES TOTAL PRICE (u 50C each MAIL TO: Radio -Electronics All payments must be in U. Reprint Department.00 Etch your own PC boards $3. Fig. However. Thus. Page 412 422 42. 3. Once reso- Mount Up The PVC helical was slipped over a strong metal fence -post.R. Follow that winding sequence to duplicate the W3FQJ performance as near as possible. All reports were the same or little difference. 2 Woke 30: Sac's acidi 000*1 424 Kepro Mouser Electronics N.) The bottom of helix is read- ily available for fine -tuning of turns after helical vertical is in position. In out initial test of this antenna. a tuner was always used between transmitter output and antenna to protect the transmitter.T. The usual metal 40 -meter vertical is more than 30 -feet high. its high end about 32 feet up.. 5. Free Information No. the through -bolt of the ground terminal rests on the fence post top.ea HOE k 4 415 423 427 ETT Electronic Warehouse Fluke Galaxy Jameco Jensen 411 Stamm) aro Handing 25.6 428 418 %I Publishing ASIC Sales Active Electronics All Electronics American Design Components Augat C. (See Fig. Keep tuned in. Each time. Winding configurations were then shifted about to obtain the very lowest SWR. Testing was done at low power. nance was obtained the SWR dropped to a level that required no tuner. support and feed. turns had to be shifted to occupy mast length. The low SWR and the wide bandwidth were not anticipated. tional 2 -1/2 feet of antenna height. As shown. A 40-meter sloping dipole was used for comparison. Radials were 31 -feet long.I. 2 that the overall length of the PVC piping was 18 feet.3 lèktronix C2 416 Trio -Kenwood Communications 57 . ADVERTISING INDEX HANDS -ON ELECTRONICS magazine does not assume any responsibility for errors that may appear in the index below.(Continued from page 105) Close spacing is used over the central portion of the vertical as can be seen in Fig. after adding several turns to base of helix. The metal fence post was driven into the ground and when the mast is set atop the fence post. Note in Fig.de. 5 -The author placed the radials down in a lazy "S" fashioned in order to reduce the overall length to fit COMPUTER PAPERBACK BOOKS Great Books For The Computer Hobbyist CHECK OFF THE BOOKS YOU WANT a space. 414 Cy State 103.S. 12 IO 20 4 5 30 27-29 Command Productions 41. NY 11762 -0240 Nume& d books o. t O. too many turns were used initially and it was possible to note the decline in SWR between the high end and low end of the 40 -meter band. Stretch them out full length. As mentioned previously.E. On the left side of Fig.I. the very top of the helical was about 20 feet above ground.421 ELECTRONIC TECHNOLOGY TODAY INC. Ride the new wave (antenna) of the future. the number of winding turns between the sequence of eye -bolts is given. No guys are required.. Then we began to clip away as the SWR kept falling until we removed approximately ten feet of wire. VK contacts were made almost immediately. that provided an addi- r 8' Fig.106 9 11 C4 Io C3 410 425 Add ens 16 31 13 14 3 Sales Tax INY State Residents onryt Name 30 6-7 Halted ICS Total Psce of Books TOTAL ENCLOSED 106 Deltex Digi -Key Educalc Electronic Book Club Radio Shack R -F: Bookstore 14 8 8 17-19 37-39 15 105 41. we tried zigzagging the radials out to 8 feet and. the same low SWR and bandwidth obtained. Massapequa Park.9 417 420. and is much more difficult to erect. The results were more startling. 2. '. 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FLUKE 73 FLUKE 75 FLUKE 77 $85 $99 $129 Analog/digital display Analog/digital display Analog/digital display 45Its ohms. élective July Patent pending 1. they've become the worldwide champions of the industry.Take hon e a world champion. list price. 2. Never before have such tough. Ext. analog battle. For your nearest distributor or a free brochure. 1984 FLUKE Ide . Choose from the Fluke 73. Or the deluxe Fluke 77.496 -1350. Take home a world champion.800 . American made meters offered so many professional features at such unbeatable prices. diode Wets.000+ hour battery life. and unique "Touch Hold" function So don't settle for just a contender. ohms 104 mA lest diode test diode test Autorange Audible continuity Audible continuity 0 7% basic dc accuracy ANaarge/rarye hold "Touch Hod" !unction 2000+ hour battery lite 0 5% basic dc accuracy Autorange/range hold 3 -your warranty 2000+ hour battery lite 0 3-year warranty 2000+ hour battery 3% baste dc accuracy 3 -year warranty Multipurpose holster ' FOR TECHNICAL DATA CIRCLE 415 © 1984. then beeps to alert you. peaking. the ultimate in simplicity. with its own protective holster ** that captures and holds readings. call 1- From outside the 402 . Winners of the digital vs. The feature. 229. plus a responsive analog bar graph for quick visual checks of continuity. nulling and trends.227 -3800. call toll -free anytime 1. The Fluke 70 Series. Ad No. Inc. John Fluke Mtg Co.S .S. 104. Ext. Since their debut. You also get the extra resolution of a 3200 count LCD display.packed Fluke 75. ohms 104 mA Volts. All rights reserved. U. 229. FROM THE WORLD LEADER IN DIGITAL MULTIMETERS. Each comes with a 3 -year warranty. and instant autoranging. 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