19-04-2011, 05:00 PM
PRESENTED BY
Biswajit Das
Mukesh Kr. Guleriya
Nikhil Sood
Ankur Chauhan
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LIST OF COMPONENTS
1. LDR
2. LM 324
3. ULN 2003
4. RELAY
5. VOLATGE REGULATOR (IC-7805, 7812)
6. LED (White & red)
7. RESISTOR (10KΩ, 220Ω)
8. CAPACITOR (2200µF,110µF)
9. DIODE
10. Transformer (12-0-12)
PROJECT WORKING
The circuit presented here can be used as a lock for important electronic/electrical appliances. When card is inserted inside its mechanism, depending upon the position of punched hole on the card, a particular appliance would be switched on. The card is inserted just like a floppy disk inside the disk drive. This card should be rectangular in shape with only one punched hole on it
The circuit uses four LDR and four white LED’s. When there is no card in lock then light is fall on LDR, the strength of LDR is adjusted by variable resistor (1kΩ). When light is fall on LDR, the resistance of LDR varies according to the incident light, so the resistance of LDR becomes low and current starts flowing through it. The LDR is connected to comparator IC (LM-324) and other input is given directly. At pin 4 and 11 the supply input is given, 5 Volt and 0 Volt respectively. The output is taken from pin no. 1, 7, 8 and 14. These output is connected to the ULN2003 and corresponding red LED’s. The ULN2003 IC works at 12 volt which is given at terminal 9 and terminal 8 makes ground. When output of LM324 is given at terminal 1, 2, 3, 4 then output is obtained at terminal 16, 15,14, 13 respectively means corresponding output is obtained and Relay’s is connected to these outputs for driving the corresponding appliances.
When card for appliance 1 is inserted then LDR of corresponding card is working and then comparator IC compare both the inputs, if output is high the signal is given to the ULN2003 and corresponding LED is glow and corresponding output of ULN is obtained at other side. Relay is connected between the ULN and appliance. When signal is applied at the Relay, it connects to the corresponding appliance for working and the appliance start working.
