Car Theft Alarm Circuit

Auto security systems are essential today to prevent our vehicle from robbery. So, nowadays people spend lots of money in  auto security systems could be a 5-20% of the cost of that vehicle. Since the auto security systems and auto alarm systems that are available in the market, may cost you huge, here is a car theft alarm that looks very simple in design and may easily implemented if you have the right ideas. This will be useful for small cars to prevent from theft. It can also be used as a auto home security system with necessary alterations.


        This auto security circuit contains two 555 timer ic as the core. The output of the circuit may be connected to  horn relay of the car. 

Setting the Circuit

Download and zoom the circuit image to get the details

To set the circuit we have to turn on the switch S1 and turn off switch S2. But door of the car  must be closed immediately within 6 seconds after S2 is turnned off. Because the timer starts working within that time and it switches the supply to horn automatically when anyone tries to open the door of the car .

Working

The IC1 is used to set the time for closing the door and IC2  is used to set the time for sound the horn after the door is opened. We can set time delay of the burglar alarm using the C1,C2,R1,R2 capacitors and resistors.

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