Car anti-theft system
On the basis of just two cheap integrated type 555 timers(CRUI), you can collect affordable automobile anti-theft system. It a schematic diagram is shown in the figure.
Integral timer And gives you the stamina needed for the driver, sitting in the car, managed to disable anti-theft system. This eliminates the need for an external switch. The thyristor prevents the timer In otherwise from sensors-switches located at vulnerable points on the machine.
The timer And performs a dual function - provides exposure time (it is approximately equal to 1.1 RaCa), sufficient not only for the driver, including anti-theft system, managed to get out of the car, but also to ensure that he, sitting in the car, managed to shut down the system. Due to this, the exposure time may be necessary to set out the interior of the car switch what always uncomfortable, not to mention the fact that the attacker can always detect this switch, In this case the toggle switch for on and off the system can be hidden somewhere behind the dashboard of the car.
When the system is turned off, the decay of the output pulse of the timer And starts the timer When the system is turned on, the thyristor allows you to start the timer In only from actuation of one of the sensors - switches grounding type located at vulnerable points on the machine.
Publication: N. Bolshakov, rf.atnn.ru