Elektronsko sandučeElektronsko sanduče vas upozorava kada vam je pristigla pošta. U kolu se nalazi ultra brajt bela dioda i foto-otpornik (LDR). Kada poštar ubaci u sanduče pismo, pismo pada između led diode I foto-otpornika tako prekida kolo i zujalica se aktivira. Zujalica ne prestaje sa radom sve dok ne izvadite poštu. Da bi rad ovog kola imao efekta morate LED diodu i LDR držati na suprotnim stranicama poštanske kutije. Odlično strašilo za poštare. The circuit uses a high bright White LED and an LDR to detect the arrival of mail in the box. IC NE 555 is designed as a Schmitt trigger by shorting its trigger pin 2 and threshold pin 6. When the light from the LED illuminates the face of LDR, it conducts taking the pin 6 of IC low. Output pin 3 then remains low inhibiting the buzzer. When a mail falls between the LED and LDR, light from LED will be blocked and the LDR becomes non conducting. This makes the threshold pin of IC high and its output goes high. The high output makes buzzer active and music will be heard. The music stops only when the letter is removed from the box. Keep LED and LDR at the opposite sides of the box. Read more: http://electroschematics.com/3800/electronic-mail-box/#ixzz1EzEehDud Čitaj dalje> Čuvar biljaka 14. jun 2010. Logička kola Ostavite komentar Oznake: biljke, cmos, LED, logicka kola, zalivanje Ovo kolo je za ljubitelje biljaka koji su zaboravni. Kolo je namenjeno da vas obavesti kada je vašoj biljci potrebno zalivanje. LED dioda vas upozorava kada je dno vaše saksije suvo tako što trepće niskom učestanosti. Podešavanjem R2 otpornika podešavate osetljivost kola u zavisnosti od saksije i okruženja. Zanimljivo je da ovo kolo troši 150µA kada je LED ugašen, a kada radi LED dioda troši 3mA. Što znači da će vam uređaj raditi godinama na dve AA baterije. This plant watering monitor circuit is intended to signal when a plant needs water. A LED flashes at a low rate when the ground in the flower-pot is too dry, turning off when the moisture level is increasing. Adjusting R2 will allow the user to adapt the sensitivity of the circuit for different grounds, pots and probe types. Read more: http://electroschematics.com/5837/plant-watering-monitor/#ixzz1EzEFI67k IC1A and related components R1 and C1 form a 2KHz square wave oscillator feeding one gate input of IC1B through the voltage divider R2/R3 made variable by adjusting the Trimmer R2. If the resistance across the probes is low (as when there is a sufficient quantity of water into the pot) C2 diverts the square wave to ground, IC1B is blocked and its output will go steady hight. IC1C inverts the high status to low, thus keeping IC1D blocked: the LED is off. When the ground in the flower-pot is becoming too dry the resistance across the probes will increase and C2 will be no longer able to divert the square wave to ground. Therefore, IC1B output begins to transfer the 2kHz signal to IC1C which, in turn, passes it to the oscillator built around IC1D. No longer disabled by a low level on its input, the IC1D oscillator slowly pulses Q1 base low causing the LED to flash, signalling the necessity to water the plant. The short low pulse driving the base of Q1 is actually a burst of 2kHz pulses and therefore the LED flickers about 2,000 times per second – appearing to the human eye as if the LED was steadily on for the entire duration of the pulse. Some notes on this plant watering monitoring system • • A square wave is used to avoid problems of probes oxidization. Probes are made with two pieces of bare, stiff lighting cable of 1mm diameter and should be about 60mm long. • • • The probes should be driven fully in the pot’s ground about 30 – 50mm apart. Please note that all parameters regarding probes material, dimensions and spacing are not critical. Current consumption: LED off = 150µA; LED on = 3mA for 0.1 sec. every about 2 sec. allowing the battery to last for years. The quiescent current consumption is so low that the use of a power on/off switch was considered unnecessary. In any case, to switch the circuit completely off, you can short the probes. Plant Watering Monitor circuit diagram Components Values R1,R4 – 470K 1/4W Resistors R2 – 47K 1/2W Trimmer Cermet or Carbon R3 – 100K 1/4W Resistor R5 – 3K3 1/4W Resistor R6 – 15K 1/4W Resistor R7 – 100R 1/4W Resistor C1 – 1nF 63V Polyester Capacitor C2 – 330nF 63V Polyester Capacitor C3,C4 – 10µF 25V Electrolytic Capacitors D1 – 1N4148 75V 150mA Diode D2 – 5mm. Red LED IC1 – 4093 Quad 2 input Schmitt NAND Gate IC Q1 – BC557 45V 100mA PNP Transistor P1,P2 – Probes (See Notes) B1 – 3V Battery (2xAA, N or AAA 1.5V Cells in series) Read more: http://electroschematics.com/5837/plant-watering-monitor/#ixzz1EzECskXG Svjetlo/mrak aktivirani relej Sve dijelove je lako za kupiti. S trimerom se podešava razina na kojoj se uključuje okidač. Bolje koristite 1N4001 diodu ako ste u mogućnosti! Zamjena za 2N2222: NTE123A, ECG123A, PN100....