2B-DELUXE CAR COMBINATION LOCK
We have published a car combination lock circuit in the Volume 2 of our Tested Electronics Projects Book. In that circuit we have used 4 no. IC555 and one IC 4017. In the same series now we have presented this project which is of small size, cheap and very useful. You can use this project on the main entrance of your house, in your cash box or for your automobiles. The main attraction of this project is that its code no. works only when it is pressed before a fixed interval.
TECHNICAL DESCRIPTION AND WORKING
This project has been developed and tested O.K. in our TV Engineers Technical Lab. The components and PCB used in the projects published in our books are available for sale at resonable price.
In this modern electronic age the thief also has modernised because old technique is becoming useless now. The project presented is a new wonder of the electronic age. The main attraction of this project is that it does not operate if dialed on a wrong number or dialed before a fixed interval. The circuit which is based on the working of IC CD4066 seems to be very difficult unless you do not know the code for operating the gate. IC CD 4066 is a analog switch IC. The pin no. 1 & 9 is its supply pin. Pin no. 13,5,12 and 6 are the triggered pins. As shown in the diagram when we press S1 switch the supply from the pin no. 1 reaches pin no. 3 through the pin no. 2. Now we trigger the pin no. 5 through switch number 2. Now pin no. 3 and 4 are internally ON and supply reaches on the pin no. 11. After pressing switch S3 pin no. 12 is triggered through the pin no. 10 & 11 which are now internally ON. Now as soon as we press S4 pin no. 6 is triggered and now supply on pin no. 9 goes to on pin no. 8 and onword to the base of transister BC 148 through the resistance R5. The relay connected to the collector of this transister gets ON and relay operates. This process of triggering should be completed within 10 seconds.
PRECAUTIONS WHILE ASSEMBLING THE PROJECT:-
* The CMOS IC get spoiled through anti-static charge. Do not touch IC with hand because human body gets charged with anti-static charge.
* Do not solder CMOS IC directly on PCB. Use the IC base.
* While soldering diode take care of its polarity.
* Do not solder IC directly on PCB because due to leakage current from the soldering iron parts get spoiled.
* While soldering transister take care of its base, emitter and collector.
* Don’t touch transister with your body while checking it.
* Do not keep the project ON in case of shorts in transister.
PCB [CODE 6TP10]=1
4E7 [1/2W]=1, 4K7=1, 330K=4
SWITCH [PUSH TO ON]=10
Relay 12V =1