vidyarthiplus.com vidyarthiplus.com Electric Circuits and Electron Devices LAB MANUAL 2nd year I I rd semester vidyarthiplus.com vidyarthiplus.com Ex. PAGE CONTENTS NO NO PREFACE 1 V-I characteristics of semiconductor diode 9 2 V-I characteristics of zener diode 15 3 CHARACTERISTICS OF JFET 21 4 V-I characteristics of silicon controlled rectifier. 27 5 V-I characteristics of DIAC 31 6 V-I characteristics of TRIAC 37 7 V-I characteristics of Light Dependent resistor 41 8 V-I characteristics of Light Emitting Diode 45 9 Characteristics of CE configuration 49 10 Characteristics of CB configuration 55 11 V-I characteristics of Insulated Gate Bipolar Transistor 61 Observe the waveform of half wave and full wave rectifier 12 65 circuits 13 Observe the waveform of Bridge rectifier circuits 73 14 Load regulation and Line regulation 77 15 Trace the waveform of UJT relaxation oscillator 83 16 Characteristics of UJT 87 17 Zener diode voltage regulator 91 EXTRA SYLLABUS 1 Clipper circuit 95 2 Clamper circuit 103 3 RC phase shift oscillator 107 vidyarthiplus.com 1 vidyarthiplus.com PREFACE The branch of engineering which deals with current conduction through a vacuum or gas or semiconductor is known as electronics. This electronics essentially deals with electronic devices and their utilization. An electronic device is that in which current flows through a vaccum or gas or semiconductor. Such devices have valuable properties which enable them to function and behave as the friend of man today. Electronic devices are being used in almost all the industries for quality control and automation. Before handling these devices and some instruments, we have to follow some precautions. They are as follows: Safety Precautions: CRO: An cathode Ray oscilloscope is an instrument capable of presenting a luminous xy graph of any two related electrical parameters Do not place objects on the top of CRO Do not insert wires or pins into ventilation holes. Do not pull the instrument by probes Never place a soldering iron on the oscilloscope frame. Do not turn the focus & intensity knob to maximum position these should be in middle position. Do not apply signals which exceed 400v peak 1KHZ Function Generator: It is an electronic device which is used to produce signals such as sine wave, square wave, and triangular wave, saw tooth wave. Frequency fine & course knob should be in minimum position. We should select only one of frequency range & required wave forms of function generator. Attenuation knob should be in released position. Do not pull & Do not place any objects on the top of function generator vidyarthiplus.com 2 Select proper type & range of (AC / DC) meters Do not change the +ve & -ve terminal Do not make any short circuit Safety depends upon good earthing always keep earth connections in good condition.com 3 . when you are doing the experiment. It produce DC voltage of range from 0 to 30v. 50v etc.com RPS: It means regulated power supply. Circuit breaker. General Precautions: Do not touch the live terminal. All the knobs are handled by slow manner not by rough manner. vidyarthiplus.vidyarthiplus. In this lab we have some safety devices they are 1. Any things are not placed on top of the RPS. Wear rubber soled shoes. Initially current knob should be in maximum position. Shut off power supply before connecting the instruments. Fuses 2. Initially voltage fine & course knob should be in minimum position. vidyarthiplus.com CHARACTERISTICS OF PN JUNCTION DIODE Forward Bias: Reverse Bias: vidyarthiplus.com 4 . The junction offers very high resistance to current flow. The outstanding property of a crystal diode is to conduct current in one direction only. connect negative terminal of the battery to Anode and positive terminal of the battery to cathode. The potential barrier is reduced and at some forward voltage (0. In this biasing. No current flows in the circuit. FORWARD & REVERSE CHARACTERISTICS OF SEMI CONDUCTOR DIODE AIM: To draw the forward & Reverse characteristics of semi conductor diode & to determine it's cut-in voltage. The potential barrier is increased. 1 7 Connecting Wires . vidyarthiplus.1 to 0.com 5 .vidyarthiplus. APPARATUS REQUIRED: SL. FORWARD BIASING: When we apply forward bias across the diode. The junction offers low resistance Current flows in the circuit.com 1. REVERSE BIASING: To apply reverse bias. 1 set THEORY: A PN junction is known as a semiconductor (or) crystal diode.3v) it is eliminated altogether. NO APPARATUS NAME RANGE QUANTITY 1 RPS (0-30)V 1 (0-30 mA) MC 1 2 Ammeter (0-100 mA) MC 1 (0-1V) MC 1 3 voltmeter (0-30V) MC 1 1K 1 4 Resistors 10 K 1 5 Diode 1 N 4001 1 6 Bread board . com MODEL GRAPH: If (mA) VBR Vr (Volts) Vc Vf (Volts) Ir (mA) VC = cut-in voltage VBR = break down voltage vidyarthiplus.vidyarthiplus.com 6 . com PROCEDURE FORWARD BIASING: Connect the circuit as per the circuit diagram Vary the power supply voltage in such a way that the readings are taken in steps of 0. Note down the corresponding ammeter readings. Note down the corresponding ammeter readings.r=del V/del I vidyarthiplus. Plot the graph: V against I Find the dynamic resistance .vidyarthiplus.com 7 .1v in the voltmeter till the needle of the power supply shows 20 v. Plot the graph: V against I Find the dynamic resistance=del V/del I REVERSE BIASING: Connect the circuit as per the circuit diagram Vary the power supply voltage in such a way that the readings are taken in steps of 1v in the voltmeter till the needle of the power supply shows 20v. No (volts) (volts) (Amps) Model calculation: V Dynamic resistance = r = ----.com TABULATION Forward Bias Input voltage Output voltage Output current Sl. No (volts) (volts) (Amps) Model calculation: V Dynamic resistance = r = ----.vidyarthiplus.Ω I TABULATION Reverse Bias Input voltage Output voltage Output current Sl.Ω I vidyarthiplus.com 8 . What is the difference between PN junction diode & zener diode? 8. What is the use of diode? 5. Define semi conductor diode 3. TV receivers 4.com 9 . What is the value cut in voltage in silicon. Define semi conductors. What are the doping materials used? 11. 12. Define breakdown voltage? 7. What is doping? 10. What is the material used for P layer & N layer. germanium? 14. What does a diode do? 2. amplifier. Video cassette recorders 5. TV assemble 2. Oscillators. Rectifier. UPS manufacturing 3. Employment: 1. Computer 2. detectors 6. TV 3. What is the name of the layer which is developing at reverse biased condition at the junctions? 13. Radio assemble List of viva voce questions: 1. 9.vidyarthiplus. Define the term cut-in voltage? 6. cut-in voltage are as follows.voltage = -------------------volt ********** vidyarthiplus. Dynamic forward resistance = --------------ohm Dynamic reverse resistance = --------------ohm Cut-in. What is bias? RESULT: Forward & reverse bias characteristics of junction diode are plotted & their dynamic resistances. What is barrier potential? 4.com Application: 1. Radio. com 10 .vidyarthiplus.com CHARACTERISTICS OF ZENER DIODE Forward Bias: Reverse Bias: vidyarthiplus. com 2. The diode current increases rapidly. vidyarthiplus.com 11 . 2.vidyarthiplus. This causes a very thin depletion layer. In reverse bias condition two things happen when Vz is reached. In forward biased condition. No Apparatus Name Range Quantity 1 RPS (0-30) V 1 No 2 (0-3V) MC Voltmeter 1 No (0-30V) MC 3 Ammeter (0-100mA) MC 1 No 4 Bread board 1 No 5 1K Resistors 1 No 10 K 6 Zener diode FZ5. As a result. It is heavily doped to reduce the reverse breakdown voltage. it is similar to the ordinary PN junction diode. APPARATUS REQUIRED: Sl. The reverse voltage Vz across the diode remains almost constant. OBJECTIVE: To measure the effects of forward & reverse bias ON current in zener diode. FORWARD & REVERSE CHARACTERISTICS ZENER DIODE AIM: To draw the forward & reverse characteristics of zener diode. 1.1 1 No 7 Connecting Wires 1 set THEORY: A zener diode is a special type of diode that is designed to operate in the reverse breakdown region. Determine its cut-in voltage & breakdown voltage. a zener diode has a sharp breakdown voltage Vz. com 12 .com TABULATION Forward Bias Input voltage Output voltage Output current Sl. No (volts) (volts) mA (Amps) vidyarthiplus.vidyarthiplus. No (volts) (volts) m(Amps) Reverse Bias Input voltage Output voltage Output current Sl. Note down the corresponding ammeter readings. Plot the graph: V against I vidyarthiplus.com 13 .vidyarthiplus. Beyond this voltage.1v in the voltmeter till the needle of the power supply shows 20 v. Note down the corresponding ammeter readings. Plot the graph: V against I REVERSE BIASING: Connect the circuit as per the circuit diagram Vary the power supply voltage in such a way that the readings are taken in steps of 1v in the voltmeter till the needle of the power supply shows 20v. current increases. but supply voltage constant. The reverse characteristics graph is decreasing upto breakdown voltage.com PROCEDURE: FORWARD BIASING: Connect the circuit as per the circuit diagram Vary the power supply voltage in such a way that the readings are taken in steps of 0. com 14 .vidyarthiplus.com MODEL GRAPH: If (mA) Vz Vr (Volts) Vc Vf (Volts) Ir (mA) Vc = cut-in voltage Vz = Zener break down voltage vidyarthiplus. Regulator circuits 3. Which part of the material is heavily doped? 3. Cut .in voltage = -------------V Break down voltage = --------------V ********** vidyarthiplus. Define the term zener diode 2. What portion of a zener diode characteristic is most useful for voltage regulator application? Why? Result: Thus the VI characteristics of zener diode was drawn & its cut-in voltage & breakdown voltage were determined.com 15 .com Application: 1. Which is the most important semiconductor material? 5. Voltage reference standards.vidyarthiplus. Voltage Stabilizers 2. What is zener breakdown? 4. What is power diode? 7. Voltage stabilizer manufacturing Viva voce question: 1. Employment 1. How many types of diodes? What are they? 6. VDS (0-30) V VGS V (0-5) V V - RPS + - + (0-30) V vidyarthiplus. + RPS . + A 470 Ω D G BFW11 S + .com CHARACTERISTICS OF JFET: CIRCUIT DIAGRAM: (0-10) mA 1.com 16 .2K Ω .vidyarthiplus. vidyarthiplus.com 17 .com 3. It acts like a voltage controlled device that means input voltage (VGS) controls the output current (ID) vidyarthiplus. 1 set THEORY: A junction field effect transistor is a 3 terminal semiconductor device in which current conduction is done by one type of carrier. CHARACTERISTICS OF JFET AIM: To draw the drain and transfer characteristics of JFET and determine the pinch off voltage APPARATUS REQUIRED: Apparatus Range Quantity RPS (0 – 30V) 1 470 Ω 1 Resistors 1. electrons and holes. 1 Connecting Wires . ie.2 KΩ 1 Ammeter (0 – 10 mA) 1 (0 – 30V) MC 1 Voltmeter (0 – 15V) MC 1 JFET BFW 11 1 Bread board . com MODEL GRAPH: DRAIN CHARACTERISTICS: TRANSFER CHARACTERISTICS: vidyarthiplus.com 18 .vidyarthiplus. The above process is repeated for two more constant VGS values. the gate – source voltage (VGS) and the corresponding ammeter readings (ID) are noted and tabulated.vidyarthiplus. vidyarthiplus. TRANSFER CHARACTERISTICS: By using RPS 2.com PROCEDURE: DRAIN CHARACTERISTICS: Connections are given as per the circuit diagram The voltage VGS is kept constant by varying RPS 1. the voltage across drain and source (VGS) and the corresponding ammeter readings (ID) are noted. the voltage VDS is kept constant.com 19 . NO VDS(V) ID(mA) VDS(V) ID(mA) VDS(V) ID(mA) TRANSFER CHARACTERISTICS: VDS = VP S.NO VGS(V) ID(mA) vidyarthiplus.com TABULATION: DRAIN CHARACTERISTICS: VGS = 0V VGS = -1V VGS = -2V S.com 20 .vidyarthiplus. we have to use JFET RF amplifier in a receiver. JEET can act as an buffer amplifier 2. Why is the input impedance of a FET higher than that of an ordinary transistor? 3. What is the basic operational difference between a FET and an ordinary transistor? RESULT: Thus the drain and transfer characteristics of JFET were drawn.vidyarthiplus. In communication electronics. ********** vidyarthiplus. Used in phase shift oscillators 3. What is a FET? 2. VIVA: 1.com APPLICATIONS: 1.com 21 . vidyarthiplus.com 22 .com CIRCUIT DIAGRAM: vidyarthiplus. vidyarthiplus.r. CHARACTERISTICS OF SILICON CONTROLLED RECTIFIER AIM: To draw the V – I characteristics of the given SCR & to determine the gate current for different anode voltage OBJECTIVE: To observe how gate current is used to switch SCR on. If the reverse voltage is increased. SCR can close at much smaller supply voltage. FORWARD CHARACTERISTICS: When anode is positive w.r. avalanche breakdown occurs and the SCR starts conducting heavily in reverse direction. the curve between V-I is called forward characteristic. Under this condition. 1 set THEORY: A silicon controlled rectifier is a semiconductor device that acts as a true electronic switch. It can change AC into DC as like as an ordinary rectifier and at the same time it can control the amount of power fed to the load. If the supply voltage is increased from zero.com 4. 1 6 Resistors 1K / 5W 2 7 Connecting Wires . the voltage across SCR suddenly drops and most of the voltage appears across the load resistance RL. REVERSE CHARACTERISTICS: When the anode is made negative w.com 23 .t to cathode. It is similar to the ordinary PN junction diode. the curve between V & I is called reverse characteristics. If proper gate current is made to flow. vidyarthiplus. NO APPARATUS NAME RANGE QUANTITY 1 RPS (0-30) V 2 0-100mA (MC) 2 Ammeter 1 0-10mA (MC) 3 Voltmeter 0-30v (MC) 1 4 SCR TYN 604 1 5 Bread board .t cathode. APPARATUS REQUIRED: SL. a point is reached when SCR starts conducting. No VAK (V) IA (mA) VAK (V) IA (mA) vidyarthiplus.vidyarthiplus.com MODEL GRAPH: If (mA) ON state IH VBR Vf (Volts) Vr (Volts) VBO IH = Holding Current VBO = Break Over Voltage Ir (mA) VBR = Break Down Voltage TABULATION: IG 1 = IG2 = Sl.com 24 . Application: Speed control of A.C.vidyarthiplus.com 25 . Increase the VAK in steps of 1 V till its maximum.C. It can be used as converter.C circuit breaker It can be used as inverter Battery chargers Phase control. VAK. in steps of 0. & D. Note down the current at that point called latching current. you can assemble inverter. Employment: This skill used for wind mill control. machines Temperature control A. Set gate current IG equal to firing current vary anode to cathode voltage.5 V & note down the corresponding anode current IA.C. & D.com PROCEDURE: Connect the circuit as per the circuit diagram. rectifier Viva voce: What is SCR? What is the function of SCR What is latching current? What is holding current? When the SCR is ON? What is avalanche break down? What are the classifications of thyristors? Which is called uni directional devices? Why this name? What is the difference between uni directional & bidirectional devices? Which device is the best device? What are the turns off methods? What is natural commutation? What is forced commutation? Which method is the best for turn on SCR? Draw the symbol of SCR? How many terminals in thyristor or SCR? What is break over voltage? Result: Thus the given SCR characteristics were drawn. It is used in light dimming control circuits It can be used as static contactor. ********** vidyarthiplus. VBO is the point where voltage suddenly drops & there is sudden increase in anode current IA. Open the gate terminal & decreases the VAK. com 26 .com MT1 NEGATIVE MT2 POSITIVE: MT1 POSITIVE MT2 NEGATIVE: vidyarthiplus.vidyarthiplus. the leakage current will continue to flow until the voltage reaches the break over voltage VBO. At this point avalanche breakdown occurs and the device exhibits negative resistance. CHARACTERISTICS OF DIAC AIM: To draw the VI characteristics of the given Diac & to determine the cut .in voltage OBJECTIVES: To study the forward & reverse current characteristics of a DIAC APPARATUS REQUIRED: Sl. When a positive or negative voltage is applied across the terminals. current through the device increases with the decreasing values of applied voltage.com 5. No Apparatus Name Range Quantity 1 RPS (0-300) V 1 2 Voltmeter (0-100V) MC 1 3 Ammeter (0-10mA) MC 1 4 Resistors 1 KΩ 1 5 Diac DB3 1 6 Bread board 1 7 Connecting Wires 1 set THEORY: A diac is a two terminal bidirectional semiconductor device which can be switched from OFF state to ON state for either polarity of applied voltage. As the applied voltage is increased. only a small amount of leakage current flow through it.com 27 . vidyarthiplus. ie.vidyarthiplus. vidyarthiplus.com 28 .com Tabulation: MT1 is positive with respect to MT2 negative. No Voltage (V) Current (mA) MT2 is positive with respect to MT1 negative Sl. Sl. No Voltage (V) Current (mA) vidyarthiplus. com 29 .vidyarthiplus. Plot the graph V against I In the above procedure is repeated for MT1 is negative with respect to MT2.dimming circuits. Note down the corresponding ammeter readings. Phase control vidyarthiplus. Relaxation oscillator 5. 2. Diac is used as triggering device in light . 4. In motor control circuits. In heat control circuits 3. Varying the supply Vary the power supply voltage in such a way that the readings are taken in the voltmeter. APPLICATION: 1.com PROCEDURE: MT1 is positive with respect to MT2 Rig up the circuit as per the circuit diagram. r.VBO + VBO MT1 + IVE w.vidyarthiplus.r.com MODEL GRAPH: ON state MT2 + IVE w.t MT1 IBO .com 30 .t MT2 VBO = Break Over Voltage vidyarthiplus. Is the doping of the two junctions equal? 8.V ********** vidyarthiplus. Why Diac is a bidirectional device? 3. What is Diac? 2. How many layers in the diac? 4.on? 9. Define cut-in voltage? 7. Cut-in voltage=--------------. Why the diac terminal name is MT1. Why doping level equal in Diac? RESULT: Thus the V-I characteristics of the given diac was drawn and cut-in voltage was determined. How the doping level in the transistors compare to Diac? 10. MT2? 5.com 31 . In a diac.vidyarthiplus.com EMPLOYMENT: This skill is used for lighting industry Domestic appliance industry VIVA VOCE QUESTIONS: 1. When the diac is turn . Does the diac conduct equally during the positive & negative alternations? 6. vidyarthiplus. - .com CIRCUIT DIAGRAM: (0-100) mA 1K/5w .com 32 . + A IMT2 MT2 BT136 RPS (0-50) mA + (0-30) V 1KΩ/5W G + + A . MT1 V (0-15) V + IG . RPS (0-30) V G vidyarthiplus. vidyarthiplus. its characteristics in I and III quadrants are essentially identical to those of an SCR in the I quadrant. PROCEDURE: 1. but in normal operation usually the gate voltage is positive in I quadrant and negative in III quadrant. The greater the gate current.vidyarthiplus. so. To set gate current Ig set VMT1. OBJECTIVES: To observe the V-I characteristics. The traic can be operated with either positive or negative gate control voltage. APPARATUS REQUIRED: Sl. The supply voltage at which the traic is turned ON depends upon the gate current. 4.com 6. 3. Connect the circuit as per the circuit diagram 2. the smaller the supply voltage at which the traic is turned on. Set have gate current equal to firing current vary anode to cathode voltage. The traic consists of 2 SCRS connected in anti-parallel. To determine the gate current for different anode voltage. Open the gate terminal & decrease VAK. No Apparatus Name Range Quantity 1 RPS (0-30) V 2 2 Voltmeter (0-15V) Mc 1 (0-50mA) Mc 3 Ammeter 1 (0-100mA) Mc 4 Resistors 1K/5w 1 5 Triac BT 136 1 6 Bread board 1 7 Connecting Wires 1 set THEORY: A triac is a 3 terminal semiconductor switching device which can control alternating current in a load. CHARACTERISTICS OF TRIAC AIM: To draw the V-I characteristics of the given triac.com 33 . VMT2 & vary Vg till VAK suddenly drop note down the corresponding IG. Vary VAK supply voltage in steps & note down the corresponding ammeter readings. Gate +ve IBO . Gate -ve VBO = Break Over Voltage vidyarthiplus.VBO + VBO MT1 +ve. No VAK (V) IA (mA) Sl.vidyarthiplus.com 34 . No VAK (V) IA (mA) MODEL GRAPH: ON state MT2 + ve.com Tabulation: IG 1 = IG2 = Sl. ********** vidyarthiplus.com 35 . What is triac? 2. Draw the symbol of Triac. How many layers. Diac? Result: Thus the VI characteristic of the given triac was plotted of the gate current for various anode voltage. What is break over voltage? 6. Why the triac is a bidirectional device? 4. What is the main function of Triac? 3.com Application: ♦ Light dimming control circuits ♦ In motor control. Employment: This skill used for transformer industry Many type of industry Viva voce question: 1. heat control circuits ♦ Other industrial applications ♦ Motor speed control ♦ For minimizing radio interference.vidyarthiplus. ♦ Electronic change over of transformer taps ♦ Static switch. terminal in the triac? 5. com 36 .com vidyarthiplus.vidyarthiplus. com 7.com 37 . b) Various supply voltage at constant illumination level. OBJECTIVES: To study the effect of an increase or decrease of light on the resistance of a photo conductive cell. The resistance rises to several megaohms under dark conditions.vidyarthiplus. electrons are liberated and conductivity of the material increases. Apparatus Required: Sl. Its resistance is then quite high. vidyarthiplus. when it absorbs light. No Apparatus Name Range Quantity 1 RPS (0-30) V 1 2 Voltmeter (0-3V) Mc 1 3 Ammeter (0-10mA) Mc 1 4 Resistors 1K 1 5 LDR 1 6 Bread board 1 7 Connecting Wires 1 set 8 Lamp 100w 1 THEORY: Light dependent resistors (LDRs) are made from cadmium sulphide containing no or very free electrons when not illuminated. CHARACTERISTICS OF LDR AIM: To draw the VI characteristics of the given LDR under a) Various illumination level at constant supply voltage. vidyarthiplus.No Distance (cm) Current (A) vidyarthiplus. Distance between bulb Distance between bulb Distance between bulb No and LDR 5 cm LDR 10 cm and LDR 15 cm Voltage (V) Current Voltage Current Voltage Current (A) (V) (A) (V) (A) Voltage = 10 volt Sl.com TABULATION: Sl.com 38 . 2. Maintain the constant input voltage. second 10 cm. Rig up the circuit as per the circuit diagram. third 15 cm) between bulb & the LDR 3. By varying the distance. Which type of material used for making LDR? 4. What is the another name of LDR? 3. the corresponding Ammeter readings are noted.OFF switch Relay control Voltage regulator Burglar alarms Object counters VIVA VOCE QUESTIONS: 1. APPLICATION: ON . What is the value of resistance of LDR at absolute darkness condition? 5. Draw a symbol of LDR? 9. Vary the voltage in the power supply in steps note down the corresponding voltmeter & ammeter readings. What is photo conductive effect? 7. 4. What is dark resistance? RESULT: Thus the V-I characteristics of LDR was drawn for various illuminations level at constant supply voltage and various and supply voltage as constant illumination level.vidyarthiplus. maintain a known distance (first 5 cm. What is illumination? 8. ********** vidyarthiplus.com 39 . Define LDR 2. What is the value of resistance of LDR at strong light condition? 6.com PROCEDURE: 1. com 40 .vidyarthiplus.com vidyarthiplus. phosphorus and arsenic. CHARACTERISTICS LIGHT EMITTING DIODE AIM: To draw the VI characteristics of the given LED. Green) 1 6 Bread board 1 7 Connecting Wires 1 set THEORY: A light emitting diode (LED) is a diode that gives off visible light when forward biased. When LED is forward biased. To determine the conduction voltage for satisfactory brightness. LED’s are made by elements like gallium. The light energy is sufficient to produce quite intense visible light. OBJECTIVES: To determine the characteristics of LED APPARATUS REQUIRED: Sl.com 8. By varying these quantities.vidyarthiplus.com 41 . it is possible to produce light of different wavelengths with colours that include red. These free electrons are the conduction band and at higher energy level than the holes in the valence band. vidyarthiplus. No Apparatus Name Range Quantity 1 RPS (0-30) V 1 2 Voltmeter (0-3V) MC 1 3 Ammeter (0-30mA) MC 1 4 Resistors 1 KΩ 1 5 LED (Red. yellow and blue. the electrons from the N-type material cross the PN junction and recombine with holes in the P-type material. When recombination takes place. the recombining electrons release energy in the form of heat and light. vidyarthiplus.com TABULATION: S.No Voltage (V) Current (Amps) vidyarthiplus.com 42 vidyarthiplus.com PROCEDURE: Rig up the circuit as per the circuit diagram. Vary the power supply voltage in such a way that the readings are taken in steps of 0.1 V in the voltmeter till the needle of the power supply shows 20 V Note town the corresponding ammeter readings Plot the graph V against I. APPLICATION: Infra red LEDs are used in burglar alarms Used in solid state video displays Used in the field of optical communication. Used in image sensing circuits. Used in numeric displays like watches, pocket calculators VIVA QUESTIONS: 1. What are the advantages of LED? 2. What is the full form of LED 3. What is the function of LED? 4. What action made when the LED reverse bias conditions? 5. What is the difference between LED & LCD 6. What is the function of photo transistor? 7. What is the range of value of operating voltage? 8. What is the difference between LED & LDR? 9. What are the advantages of opto coupler? 10. What are the different materials used for the LED? 11. What is the value of current when the typical voltage across and LED is from 1.5 V to 2.5 V? 12. What is the value of voltage at the reverse bias condition? RESULT: V-I characteristics of LED were plotted & their cut-in voltage (or) conduction voltage is as follows. Cut - in voltage = --------- V. ********** vidyarthiplus.com 43 vidyarthiplus.com vidyarthiplus.com 44 The collector current IC varies with VCE for VCE between O and IV only. APPARATUS REQUIRED: Sl. OUTPUT CHARACTERISTICS: It is the curve between collector current (IC) and collector – emitter voltage (VCE) at constant base current (IB). CHARACTERISTICS OF COMMON EMITTER CONFIGURATION AIM: To draw the input and output characteristics of common Emitter configuration for a given transistor and find the input and output resistance. This value of VCE upto which collector current IC changes with VCE is called the knee voltage (Vknee). After this. Here emitter is common to both input and output circuits and hence the name common emitter connection. input is applied between base and emitter and output is taken from the collector and emitter. 1 4 Resistor 68k 1 5 Transistor BC 107 1 6 Bread board .com 45 . No Apparatus Name Range Quantity 1 RPS (0-30) V 2 (0-2V) MC 2 Voltmeter 1 (0-30V) MC (0-100 µA) MC 3 Ammeter 1 (0-50mA) MC 1 k. collector current becomes almost constant and independent of VCE.com 9.vidyarthiplus. INPUT CHARACTERISTICS: It is the curve between base current (IR) and base – emitter voltage VBE at constant collector – emitter voltage (VCE) This characteristic resembles that of a forward biased diode curve. 1 7 Connecting Wires . vidyarthiplus. 1 set THEORY: In this arrangement. com 46 .vidyarthiplus. No VCE (V) = VCE = 5V VCE (V) = VBE (V) IB (µA) VBE (V) IB (µA) VBE (V) IB (µA) vidyarthiplus.com INPUT CHARACTERISTICS MODEL GRAPH:- Tabulation: Input characteristics: Sl. Set VCE = 5 V. 2. 3. 4.Set IB =20 micro Amps.vidyarthiplus. Formula: ∆VCE Output resistance Ro = ------. Vary VCE insteps of 1 V & note down the corresponding IC. Plot the graph VBE Vs IB for a constant VCE 5. 3. vidyarthiplus. Vary VBE insteps of 0. ♦ Used as switch ♦ Oscillator circuits ♦ Logic circuits ♦ Modulation circuits ♦ Buffer ♦ CE amplifier are used in audio. 2.com PROCEDURE: I/P Char: 1.1 V & note down the corresponding IB. radio ♦ Modulation ♦ Wave form generation.com 47 . 80 micro amps etc. Repeat the above procedure for 40 micro Amps. Formula: ∆VBE Input resistance Ri = ------. Rig up the circuit as per the circuit diagram. Find the input resistance. 4.At constant VCE ∆ IB O/P Char: 1.At constant IB ∆ IC Application: ♦ Main application of transistor is as an amplifier. Rig up the circuit as per the circuit diagram. Repeat the above procedure for 10 V. Plot the graph Vce Vs IC for a constant IB 5. 15 V etc. Find the output resistance. vidyarthiplus.com 48 . IB= IB= IB= No VCE (V) Ic µA VCE(V) IC(µA) VCE(V) IC(µA) vidyarthiplus.com OUTPUT CHARACTERISTICS MODEL GRAPH:- Tabulation: OUTPUT CHARACTERISTICS: Sl. What is the difference between BJT & UJT? RESULT: Thus the input and output characteristics were drawn. ********** vidyarthiplus. What are the three regions? 9. Define amplification factor? 15. What type of mode of operation condition the C-B forward bias.com EMPLOYMENT: This skill is used for electronics product manufacturing industry (i. What is transistor configuration? 5. What is transistor? 2. Why the transistors is used as a switch 7.e. What is gain? 16. control panel circuits. This skill is used for telephone department. What is active region? 12. What is saturation region? 14. What mode of operation is used has amplification action? 10. VIVA QUESTIONS: 1. What is the advantage of transistor? 4.vidyarthiplus.video) This skill is used for digital based project. Why transistor is called bipolar junction transistors? 3. How many terminals in the transistors? 8.com 49 . What is cut-off region? 13. Why transistor is used as an amplifier? 6. E-B junction reverse bias? 11. audio. B P .com 50 . + C IC A BC 147 A E N N . (0-15) V RPS RPS VBE V (0-1) V VCE V (0-30) V (0-30) V + + E B C BC 547 vidyarthiplus.com Input and Output Characteristics of transistor in CB configuration: (0-50) mA (0-50) mA 470 Ω IE 1.vidyarthiplus.2 KΩ . 1 Connecting Wires .com 10.vidyarthiplus. base is common to both input and output. 1 set THEORY: In this circuit arrangement input is applied between base and emitter and output is taken from the base and collector. APPARATUS REQUIRED: Apparatus Range Quantity Transistor BC 147 1 470 Ω Resistors 1 1. INPUT RESISTANCE: It is defined as V R = BE i I E vidyarthiplus. Here.com 51 . INPUT CHARACTERISTICS: It is the curve between base – emitter voltage (VBE) and emitter current (IE) at constant collector base voltage (VCB). CHARACTERISTICS OF CB CONFIGURATION AIM: To draw the input & output characteristics of common base configuration and find the input and output resistance.2 KΩ RPS (0 – 30V) 1 (0 – 1)V 1 Voltmeter (0 – 15V) 1 (0 – 10 mA) 1 Ammeter (0 – 50 mA) 1 Bread board . com MODEL GRAPH: INPUT CHARACTERISTICS: VCB = 10V VCB = 0V VCB = 5V IC VBE OUTPUT CHARACTERISTICS: Ic = 10mA IC(mA) Ic = 7mA Ic = 3mA VCB = (Volts) vidyarthiplus.vidyarthiplus.com 52 . vidyarthiplus. OUTPUT CHARACTERISTICS: BY using RPS. vidyarthiplus. IE is kept at constant Collector – base voltage is increased in number of steps and the corresponding value of collector current (IC) are noted and tabulated.com 53 . Base – emitter voltage is increased in number of steps and the corresponding emitter current IE are noted and tabulated. By varying RPS VCB is kept constant at a particular voltage.com OUTPUT CHARACTERISTICS: It is the curve between collector base voltage (VCB) and collector current (IC) at constant emitter current (IE). OUTPUT RESISTANCE: It is defined as V Ro = CB I C PROCEDURE: INPUT CHARACTERISTICS: Connections are given as per the circuit diagram. vidyarthiplus.com TABULATION: INPUT CHARACTERISTICS: VCB = 0V VCB = 5V VCB = 10V S.com 54 .NO VBE(V) IE(mA) VBE IE VBE IE TABULATION: OUTPUT CHARACTERISTICS: IE=3mA IE=5mA IE=10mA S.NO VCB(V) IC(mA) VCB(V) IC(mA) VCB(V) IC(mA) vidyarthiplus. Which material is commonly used for transistor manufacturing? RESULT: Thus the input and output characteristics of CB configuration was drawn.com APPLICATIONS: It is used in high frequency application Common base amplifier is used as a buffer amplifier. What is meant by buffer amplifier? 2. VIVA QUESTIONS: 1. ********** vidyarthiplus.com 55 .vidyarthiplus. Why it is used in high frequency application? 3. com 56 .vidyarthiplus.com vidyarthiplus. No Name of the Apparatus Numbers Reqd 1 Characteristics of IGBT kit 1 2 IGBT – IRG4BC20S 1 3 DC Voltmeter (0-30)V 1 4 DC Voltmeter (0-15)V 1 5 DC Ammeter (0-5)A 1 6 Rheostat 50 ohms . APPARATUS REQUIRED: S.com 57 . Repeat the above procedure for Vge = 5. CHARACTERISTICS OF IGBT AIM: To conduct an experiment and to draw the VI Characteristics of IGBT OBJECTIVE: To observe the relation between the collector current and collector . vidyarthiplus. Connect the meters and Rheostat in the experiment board.source voltage of an IGBT. 4.35v.25volts and adjust the rheostat to 50 ohms 5. Connect the IGBT in the circuit. 2. Note down the values of Vce and Ic for every rise in 1v in the collector – emitter voltage.vidyarthiplus. Plot the VI characteristics in the graph sheet. Switch ON the power supply.com 11.2A 1 7 Connecting wires 1 set PROCEDURE: 1. 3. Keep the Vge at 5.emitter voltage different values of gate . 6. com Tabular column: STATIC CHARACTERISTICS GATE VOLTAGE VG = GATE VOLTAGE VG = S.com 58 .vidyarthiplus.No Vce (volts) Ic (mA) Vce (volts) Ic (mA) vidyarthiplus. The inversion layer cannot be maintained when the gate voltage is below the threshold voltage. But the controlling parameter is Gate voltage rather than the base current in a BJT. It is identical with the output Characteristics of the BJT. To turn OFF the device. VIVA VOCE: 1. it requires simple drive circuit and it consumes less power. the inversion layer is formed and the current begins to flow. APPLICATION: AC and DC drives.com THEORY: IGBT has the combined advantage of Power MOSFET and power BJT. When a positive gate voltage greater than the threshold voltage is applied. UPS Solid state relays and contactors. an emitter like a BJT and an insulated gate as it is in a MOSFET. What is the control pulse of an IGBT? RESULT: Thus the VI characteristic of IGBT was drawn by conducting an experiment. Say the current rating of IGBT 4. Hence the device turns ON.vidyarthiplus.com 59 . With no gate voltage applied. Due to the input MOS gate structure. ********** vidyarthiplus. for different values of Gate-Source voltage. The IGBT has low on-state voltage drop and high forward current density compared to the power BJT and MOSFET. The IGBT is a three terminal device It has a collector. The VI Characteristics shows the relation between the Collector Current and the Collector-Emitter voltage. a negative voltage must be applied to the gate. Why is inculcated gate bipolar transistor (IGBT) popular now . It has three terminals.a days? 5. the IGBT is in the forward blocking mode. What are the applications of IGBT? 3. What is IGBT 2. com 60 .com FULL WAVE RECTIFIER: vidyarthiplus.vidyarthiplus. vidyarthiplus. APPARATUS REQUIRED: Sl. OBJECTIVES: 1. 1 set vidyarthiplus. To observe & measure the output wave forms of a full . OBSERVE THE WAVEFORMS OF HALF WAVE & FULL WAVE RECTIFIER AIM: To construct half wave & full wave rectifier circuits using diodes & observe the input & output wave forms with & without filter. 2. No Apparatus Name Range Quantity 1 CRO (0-20 MHZ) 1 2 Transformer 9-0-9 V 1 3 Diode 1N 4001 2 4 Resistor 2K 1 5 Capacitor 1000 µF 1 6 Bread board .wave rectifier.wave rectifier. 1 7 Connecting Wires .com 12.com 61 . To observe & measure the output wave forms of a half . com 62 .com HALF WAVE RECTIFIER: vidyarthiplus.vidyarthiplus. com THEORY: HALF WAVE RECTIFIER: In half – wave rectification.com 63 . the rectifier conducts current only during the positive half cycles of input ac supply.vidyarthiplus. one diode supplies current to the load and for the negative half cycle. FULL WAVE RECTIFIER: In full wave rectification. For positive half cycle. This can be achieved with two diodes working alternately. The negative half cycles are suppressed. the other diodes does so. the diode becomes forward biased and hence half cycle. The diode is reverse biased and it conducts no current. In this way full wave rectifier produces dc output. current flows through the load in the same direction for both half cycles of input ac voltage. vidyarthiplus. During positive half cycle. com Half wave rectifier tabulation: Description Amplitude (V) Time period Input voltage waveform Output voltage waveform without filter Output voltage waveform with filter Input Waveform Vin (v) t (ms) Output Waveform Vo (v) (Without filter) t (ms) Vo (v) Output Waveform (With filter) t (ms) vidyarthiplus.com 64 .vidyarthiplus. com 65 . ♦ Connect the circuit to the secondary terminals of the transformer ♦ Connect CRO across the load. WITH FILTER: ♦ Rig up the circuit as per the circuit diagram ♦ Connect the capacitor across the load resistance & proceed with the above procedure. APPLICATION: ♦ Radio. ♦ Switch the CRO into DC mode & observe the wave form. Battery charger. Note its amplitude. emergency light All type of electronic industry using these circuits . ♦ Keep the CRO switch in ground mode & observe the horizontal line & adjust it to the x axis. TV ♦ Computer EMPLOYMENT: This skill very useful to all service and assembler. vidyarthiplus. 50 HZ source to the primary coil of the transformer & observe the AC wave forms of rated value without any distortion at the secondary of the transformer. Vm & frequency from the screen along with its multiplication factor. ♦ Switch on the CRO into AC mode & observe the waveform. Note down its amplitude Vm & frequency from the screen along with its multiplication factor.vidyarthiplus.com PROCEDURE: WITHOUT FILTER: ♦ Test your transformer: Give 230 V. com Full wave rectifier circuit tabulation: Description Amplitude (V) Time period Input voltage waveform Output voltage waveform without filter Output voltage waveform with filter vidyarthiplus.vidyarthiplus.com 66 . ********** vidyarthiplus.com VIVA QUESTION: 1. Which rectifier circuit has low efficiency? Why? 14. What are the types of phase rectifier? 16. What is peak inverse voltage? 12. Why the filter used in rectifier circuit? 7. How much efficiency in the full wave.com 67 . Which rectifier is mostly used? Why? 3. What is rectifier? 2. How many numbers of diodes are used in full wave rectifier? 13. What is rectifier efficiency? 8. Which components are used for rectification? 4.vidyarthiplus. Why step down transformer used for rectification? 10. What is the function of transformer? 9. half wave rectifier? 15. What is ripple factor? 11. What is advantages of three phase rectifier compound to the single phase? RESULT: Thus the half wave & full wave rectifier was constructed the input & output wave forms with & without filters were observed. What are the types of filter? 6. What is filter? 5. vidyarthiplus.com BRIDGE RECTIFIER vidyarthiplus.com 68 . 1 7 Connecting Wires . During positive half cycle. During negative half cycle. It contains four diodes connected in the form bridge. BRIDGE RECTIFIER AIM: To construct a bridge rectifier circuits using diodes & observe the input & output waveforms with & without filters.com 13.com 69 . APPARATUS REQUIRED: Sl.vidyarthiplus. so the current flow is by these diodes in same direction. vidyarthiplus. Using the bridge circuit. No Apparatus Name Range Quantity 1 CRO (0-20 MHZ) 1 2 Transformer 9-0-9 V 1 3 Diode 1N 4001 4 4 Resistor 2K 1 5 Capacitor 1000µF 1 6 Bread board . 1 set THEORY: The bridge rectifier is a full wave rectifier. the AC voltage is converted into DC. two diodes become forward biased. the remaining two diodes become forward biased. So these diodes conduct current in one direction. com Tabulation: Bridge wave rectifier circuit tabulation Description Amplitude Time period (V) Input voltage Output voltage without filter Output voltage with filter vidyarthiplus.com 70 .vidyarthiplus. com 71 . ♦ Keep the CRO switch in ground mode & observe the horizontal line & adjust it to the x axis. ********** vidyarthiplus. What is the use of bleeder resistor? RESULT: Thus the bridge rectifier was constructed the input & output wave forms with & without filter were observed. What is the value of ripple factor? 5. How many diodes are required in bridge method? 2. What is value ripple frequency? 7. ♦ Connect the circuit to the secondary terminals of the transformer ♦ Connect CRO across the load. Note its amplitude. Which type of transformer used for bridge rectifier circuit? 3. What are the advantages of bridge rectifier? 4. APPLICATION: 1. D. Note down its amplitude Vm & frequency from the screen along with its multiplication factor. Computer VIVA QUESTION: 1. 50 HZ source to the primary coil of the transformer & observe the AC wave forms of rated value without any distortion at the secondary of the transformer.C. What is average value? 6. WITH FILTER: ♦ Rig up the circuit as per the circuit diagram ♦ Connect the capacitor across the load resistance & proceed with the above procedure. motor speed control circuits 2. TV 4. ♦ Switch the CRO into DC mode & observe the wave form. Battery charger 3. Vm & frequency from the screen along with its multiplication factor. ♦ Switch on the CRO into AC mode & observe the waveform.vidyarthiplus.com PROCEDURE: WITHOUT FILTER: ♦ Test your transformer: Give 230 V. com vidyarthiplus.vidyarthiplus.com 72 . IC 7805 has the output of +5V.vidyarthiplus. Pin 1 is input 2 output and pin 3 is ground. LOAD REGULATION & LINE REGULATION AIM: To construct a voltage regulator using IC 7812 & to determine the load regulation & line regulation. No Apparatus Name Range Quantity 1 RPS (0-30V) 1 2 Voltmeter (0-15V)MC 1 3 Ammeter (0-100mA) MC 1 4 DRB .com 73 . voltage regulators are available on integrated circuits form to avoid the above drawbacks. 1 5 IC 7812 1 6 Capacitor 1000µF 2 7 Bread board . 1 8 Connecting Wires . OBJECTIVE: To measure regulation using IC 7812 APPARATUS REQUIRED: Sl. Nowadays. vidyarthiplus. IC 7805 has 3 pins. 1 set THEORY: Initially voltage regulator circuits were constructed using discrete components which had the problem of unreliable operation. frequent breakdown of components. occupying more space.com 14. In the same way negative voltage regulators are designed. com Tabulation: Load regulation: Input voltage = (constant) Sl. Output voltage Resistance (k ohm) No Line regulation: Load constant: Sl. No Input voltage Output voltage vidyarthiplus.com 74 .vidyarthiplus. Vary the load in regular steps. 3.vidyarthiplus. Note down the corresponding output voltage using a voltmeter. 3. APPLICATION: It is used for regulated power supply. 5. Plot the graph: Vin Vs Vo LOAD REGULATION: 1. Rig up the circuit as per the circuit diagram. Connect the load resistance of higher wattage. Replace the fixed resistance by a decade resistance box. Rig up the circuit as per the circuit diagram 2. 2.com PROCEDURE: LINE REGULATION: 1. 4. Fix the input DC supply voltage (Say. Note down the corresponding output voltage across the load using voltmeter. 12 V) more than the regulations value. 5. Vary the input DC supply in regular steps.com 75 . 4. It is used for radio TV It is used for computer and all type of electronic item using this voltage regulated IC vidyarthiplus. vidyarthiplus.com vidyarthiplus.com 76 . What are the types of regulation? 4. What is +ve voltage regulator? 6. What is linear regulator? 11. What is the function of regulator? 2. What is negative voltage regulator? 5.com 77 . What is series regulator? 8.vidyarthiplus. What are the disadvantages of linear regulator? 12. What is zener voltage regulator? 7. How many terminals in the IC voltage regulator? RESULT: Thus the voltage regulator IC 7812 was constructed & its load & line regulation was determined.com EMPLOYMENT: This is very useful to regulate power supply industry. What is the output voltage value for 7905 IC? 10. What is regulation? 3. VIVA QUESTION: 1. Line regulation = ------- Load regulation = ------ ********** vidyarthiplus. What is the output voltage in 7805 IC? 9. com CIRCUIT DIAGRAM: vidyarthiplus.com 78 .vidyarthiplus. the capacitor C charges through resistor R1. PROCEDURE: 1.1µF 1 DRB 1 5 Resistor 10K 1 100K 1 6 Bread board . 6. OBJECTIVE: To connect the UJT as a relaxation oscillator & observe the output wave forms. 4. Switch off the supply 7. During the charging period. The next cycle then begins. 2. the UJT goes to conducting mode and the capacitor is discharged between E and B1. Switch on the power supply set VBB = 10 V & observe the wave form on the CRO 5. Note down the practical frequency.vidyarthiplus. the voltage across the capacitor rises in an exponential manner until it reaches the peak point voltage. vidyarthiplus. Note down the practical frequency. Connect CRO across capacitor. Now. Rig up the circuit as per the circuit diagram. 1 7 Connecting Wires . 8. 1 set THEORY: When the battery VBB is turned on.com 15. the UJT is switched off. allowing the capacitor C to charge again. No Apparatus Name Range Quantity 1 RPS (0-30V) 1 2 CRO (0-20 MHZ) 1 3 UJT 2N 2646 1 4 Capacitor 0. As the capacitor voltage reached the valley point (VV).com 79 . Connect CRO across R1 switch on the supply & observe the wave forms. TRACE THE WAVE FORM OF UJT RELAXATION OSCILLATOR AIM: To construct a relaxation oscillator using UJT & trace the wave form & also measure the frequency. Set VBB = 10 V (say) ( Supply voltage normally used lies in the range 10 to 35 V) 3. APPARATUS REQUIRED: Sl. com 80 .com Tabulation: Peak voltage (V) Time in sec Frequency = 1/t Hz Tabulation: Peak voltage (V) Time in sec Frequency = 1/t Hz vidyarthiplus.vidyarthiplus. 3. Used in radar equipment 8. 4. EMPLOYMENT: TV assembler This skill is used for army Oscilloscope assembler industry VIVA QUESTIONS: 1. How many classifications of oscillators? 8. How many terminals in the UJT? 13. 5. How the frequency of oscillation determined in theoretical? 12. Used in oscilloscope. Used as sine wave generator.off ratio? 11. What is the function of oscillator? 2. What is negative resistance region? RESULT: Thus the UJT relaxation oscillator circuit was constructed & its waveforms were drawn. How does oscillation start in oscillators? 6. 6. Used as a fast acting switch. Which Condition of region the UJT is off state? 14.com APPLICATION: 1. What is the difference between oscillator & amplifier? 7. Pulse generator for firing SCR. Which portion of the characteristics used in a relaxation oscillator? 3. In the negative resistance region.com 81 .vidyarthiplus. Which oscillator is suitable for RF range application? 5. 2. ********* vidyarthiplus. Used in TV 7. When the UJT is ON? Which region? 15. saw – tooth generators. it can be operated as a relaxation oscillator. Define intrinsic stand . Used in time delay circuits. What are types of oscillators based on frequency generator? 9. square wave generators. What is crystal oscillator? 10. Which oscillator is very suitable for audio range applications? 4. vidyarthiplus. - B1 2N2646 E B2 vidyarthiplus.com 82 .com CHARACTERISTICS OF UJT: 470 Ω (0-50) mA B2 470 Ω - + A + + E 2N2646 RPS V (0-15) V (0-30) V + B1 - + - RPS V (0-15) V (0-30) V . It has only one PN junction.vidyarthiplus. BY using RPS. the voltage VB1 B2 is kept constant. CHARACTERISTICS OF UJT AIM: To draw the V-I characteristics of UJT and find the peak point voltage APPARATUS REQUIRED: Apparatus Range Quantity RPS (0 – 30V) 2 Resistors 470 Ω 2 Ammeter (0 – 50 mA) 1 Voltmeter 0 – 15V 1 UJT 2 N 2646 1 Bread board 1 Connecting Wires 1 set THEORY: Uni junction transistor (UJT) is a 3 terminal semiconductor switching device. the emitter voltage (VE) and the corresponding ammeter reading (IE) are noted and tabulated. It exhibits a negative resistance characteristics and hence it can be used as a oscillator. The above process is repeated for two more constant VB1 B2 values.com 83 . PROCEDURE: Connections are made as per the circuit diagram. vidyarthiplus.com 16. It has no ability to control the AC power with a small gain. com MODEL GRAPH: TABULATION: VB1B2 = 4V VB1B2 = 7V VB1B2 = 10V S.vidyarthiplus.NO VE IE VE IE(mA) VE(V) IE(mA) (V) (mA) (V) vidyarthiplus.com 84 . Voltage across RB1. ********* vidyarthiplus.vidyarthiplus.7 Vp = 7.5 + 0. What is peak point voltage? 3.com 85 . It is used in relaxation oscillator to generate saw tooth output. The voltage will divide up across RB1 and RB2. When no voltage applied to UJT. VIVA: 1. V1 =( RB1 / (RB1 + RB2))VBB η = V1 / VBB. Why it is called uni junction transistor? 2.7v) Vp = η VBB + VD = 0. = RB1 / (RB1 + RB2) V1 = ηVBB 3. What is valley voltage? RESULT: Thus the characteristic of UJT was obtained. If a voltage VBB is applied between the bases with emitter open.65 x 10 + 0.2v APPLICATIONS: UJT is used in oscillator.7 (VB1 B2 = 10v) = 6. In pulse generating circuits.com CIRCUIT DESIGN: 1. the interbase resistance is given by RBB = RB1 + RB2 2. If rising positive voltage is applied to the emitter. Vp = η VBB + VD Vp – peak point voltage VD – forward voltage drop across the diode (for si 0. the diode become forward biased when input voltage exceeds η VBB by VD. com 86 .1 (0-30) V - - vidyarthiplus.com ZENER DIODE VOLTAGE REGULATOR: 5K R r + + RPS RL [DRB] Fz 5.vidyarthiplus. ZENER DIODE VOLTAGE REGULATOR: AIM: To construct a voltage regulator using zener diode.com 87 .1 1 Voltmeter 0 – 10V 1 DRB 1 THEORY: A zener diode can be used as a voltage regulator to provide a constant voltage from source whose voltage may vary over sufficient range. The series resistance R absorbs the output voltage fluctuations so as to maintain constant voltage across the load. The zener diode is connected in reverse direction.com 17. The load voltage remains constant even though the input voltage and load resistance may vary over a wide range. vidyarthiplus. APPARATUS REQUIRED: Apparatus Range Quantity RPS (0 – 30V) 2 Resistors 5K 1 zener diode F Z5.vidyarthiplus. com vidyarthiplus.com 88 .vidyarthiplus. The Corresponding zener voltage is noted. ********* vidyarthiplus.com PROCEDURE: Connections are given as per the circuit diagram. Can zener be used as a rectifier? 3. APPLICATIONS: It can be used as a voltage regulator in many of the rectifier circuit.com 89 . What for purpose we connect the series resistance in the zener circuit? RESULT: Thus the zener voltage regulator was constructed and the characteristics were observed. How does a zener diode maintain constant voltage across the load? 2. In any case the zener voltage is constant.vidyarthiplus. VIVA: 1. Vary the input voltage and note down the corresponding zener voltage. Fix the input voltage and vary the RL. com 90 .com vidyarthiplus.vidyarthiplus. e. vidyarthiplus. The input waveform can be clipped at different levels by simply changing the battery voltage and by interchanging the position of various elements. APPARATUS REQUIRED: S. The clipping circuit requires a minimum of two components i. Connecting Wires -.com EXTRA SYLLABUS 1. DC battery is also used to fix the clipping level.vidyarthiplus.com 91 . 1 6. Bread Board -. RPS (0 – 30) V 1 2. FGR -. CLIPPER CIRCUIT AIM: To construct the biased positive & negative Clipper circuits using diodes. Diode 1N4001 1 3. Resistor 10 KΩ 1 4. 1 7. 1 Set THEORY: It is a nonlinear wave shaping circuit. APPARATUS REQUIRED RANGE QUANTITY 1. NO. CRO 0-20 MHZ. a diode and a resistor. 1 5. com 92 .com vidyarthiplus.vidyarthiplus. vidyarthiplus.com PROCEDURE: Connections are made as shown in fig. Power supply is switched ON. Using Function Generator we can vary the frequency and fixed at particular frequency. Now the corresponding input and output waveforms are drawn. Amplitude and time, input & output waveforms are drawn. And graph is drawn for input and output waveform. Power supply is switched OFF. vidyarthiplus.com 93 vidyarthiplus.com vidyarthiplus.com 94 vidyarthiplus.com APPLICATION: It is used in radar applications. Used in digital computers Widely used in radio and television receivers VIVA QUESTIONS: What is clipper? What is meant by biased clipper? Mention the application of clipper? Differentiate between series and shunt positive clipper? vidyarthiplus.com 95 vidyarthiplus.com NEGATIVE BIASED CLIPPER Circuit Diagram A K IN 4001 10 KΩ FGR CRO - .5 VR + MODEL GRAPH vidyarthiplus.com 96 . ********** vidyarthiplus.vidyarthiplus.com 97 .com RESULT: Thus the Positive and Negative Clipper Circuits were studied and constructed and its input and output waveforms were drawn. 100 µF A IN 4001 K FGR 100 KΩ CRO vidyarthiplus.com CIRCUIT DIAGRAM OF POSITIVE CLAMPER: 100 µF .com 98 . + K IN 4001 100 KΩ FGR CRO CIRCUIT DIAGRAM OF NEGATIVE CLAMPER: + .vidyarthiplus. PROCEDURE: Connections are made as shown in fig. a clamping circuit uses a capacitor together with a diode and a resistor. 1 5.vidyarthiplus. 1 6. A clamping circuit should not change peak to peak value of the signal. Bread Board -. To do so. Switched ON the Function generator Now corresponding input and output waveforms are visible at the monitor of CRO. Diode 1N4001 1 2. vidyarthiplus. Clampers are also sometimes known as dc restorers. Connecting Wires -. APPARATUS REQUIRED: S.com 2. CLAMPER CIRCUIT AIM: To construct and study the output waveform of Clamper Circuit. it should only change the DC level.20 MHZ 1 4. Clamping is the process of shifting the input signal above or below the zero level. FGR -. 15 THEORY: Clamping is the process of introducing a dc level into an ac signal. APPARATUS REQUIRED RANGE QUANTITY 1. Amplitude and Time of input and output waveform is measured and tabulated.com 99 . CRO 0. NO. Capacitor 100µF/25V 1 3. com 100 .com MODEL GRAPH POSITIVE CLAMPER Amplitude (v) Time (ms) 2Vm Vm Time (ms) NEGATIVE CLAMPER Amplitude (v) Time (ms) Time (ms) -Vm -2Vm vidyarthiplus.vidyarthiplus. Used to produce a D. What is the difference between the clipper and clamper? RESULT: Thus the Clamper Circuits were constructed and its input and output waveforms were drawn. 2. What is the other name for clamper? 2.com 101 .com APPLICATION:- 1. Used in television receivers to restore the original D. ********** vidyarthiplus.C voltage whose value is multiple of peak AC input applied voltage. What is clamper? 3.C reference signal to the video signal. VIVA QUESTIONS: 1.vidyarthiplus. Mention the application of clamper? 4. com 102 .com vidyarthiplus.vidyarthiplus. APPARATUS REQUIRED RANGE QUANTITY 1. In this case the CE amplifier is followed by a frequency determining network.RC network may be used as positive feedback between input and output. and square wave etc. R2 combination provides dc potential divider bias and Ro. APPARATUS REQUIRED: S. Rheostat 1KΩ 1 4. CE provides temperature stability and provides ac signal degeneration. triangular.3KΩ 4 THEORY: It is a circuit which self generating some waveform like sine.1 µf 4 3. The R1. NO.com 3.vidyarthiplus. Transistor BC 108 1 2. The high pass or low pass RC . vidyarthiplus. It is basically an amplifier circuit with positive feedback introduced.com 103 . Capacitor 0. RC PHASE SHIFT OSCILLATOR AIM: To construct and draw characteristics of RC Phase Shift Oscillator. Resistor 3. vidyarthiplus.com 104 .com MODEL GRAPH RC PHASE SHIFT OSCILLATOR Amplitude (V) Time (ms) vidyarthiplus. The amplitude and time are measured then the graph is drawn.248 kHz VIVA QUESTIONS: Why is an RC phase shift oscillator so called? Mention two low frequency oscillators Why LC oscillators are not used at audio frequencies? What is the condition to initiate oscillations? RESULT: Thus RC Phase Shift Oscillator characteristics were drawn and constructed. Power supply is switched ON.com PROCEDURE: Connections are made as shown in circuit diagram.vidyarthiplus. ********** vidyarthiplus.com 105 . Now corresponding output is taken in CRO. Varying the RPS and kept at a fixed voltage between 6V – 12V. FORMULA: 1 F= 2 πRC 6 DESIGN: R = 200kΩ C = 100pF F=? 1 F= 2 πRC 6 1 = 2 π × 200 × 10 × 100 × 10 −12 6 3 = 3.