Tuesday, November 2, 2010

Simple Car Theft Deterrent

The purpose of this simple circuit is to deter potential car burglars by flashing a few LEDs on a seemingly very sophisticated control panel,implying that the vehicle is equipped with a sophisticated hi-tech alarm system. This simple deterrent is unique in the sense that it is based on just one single uni junction (UJT) and is connected to the car power supply system by just two wires.

The circuit partly relies on it self and partly on the psychological fact that on seeing a brightly lit and active control panel ( even when the car is off ) similar to an alarm system, many thieves, especially the more experienced ones, would don't like to.... to dare to attempt stealing the car at the risk of setting off the alarm.

The circuit as shown in schematic, is based on a UJT type 2N2646, which is wired as a low frequency oscillator. The frequency is determined by the timing  components R1 and C1. Two LEDs are used in flashing mode and two in normal forward conduction pilot mode.R2 and R3 limit the currents passing through the LEDs .       

The circuit Simple Car Theft Deterrent

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