The following circuit diagram apply for Car Alarm and Immobilizer System. This circuit features exit and entry delays, an intermittent siren output and automatic reset, an instant alarm zone. You can immobilize the vehicle and flash the lights just by adding an external relays. The circuit uses a Cmos 4011. It has four two-input NAND gates. These gates only have a low output when both inputs are high. While at least one input is low – the output pin will remain high.
The electronic components used include resistor, transistor, diodes, CMOS IC, zener, capacitor, 25 watt electrolytic and a relay. The design has a number of advantages. It operates automatically when you turn the ignition off – so there’s no need to remember to activate it. The relay uses no current while the ignition is off – so there’s no drain on the battery. To de-activate it you’ll need to have the ignition key and you’ll need to know the whereabouts of the push-switch.