Posted on Sep 25, 2012

See (a) for the timing information for the alarm circuit in (b). When leaving your vehicle, flip the arming switch and close the door to arm the device. Subsequent opening of an entrance triggers both timers. After the expiration of the entry delay timer, the alarm sounds for a time determined by the second timer. The value of R should be less than 1 KO. If you use an incandescent lamp instead of a resistor, you get an extra function-an open-entrance indicator.

Click here to download the full size of the above Circuit.

By keeping the resistance low, you avoid false tripping should water collect under the hood. If your door switch connects the courtesy light to 12 V rather than ground, use a single transistor as an inverter at the input.

Leave Comment

characters left:

New Circuits



Popular Circuits

How to design A class amplifier
Warble Alarm Circuit
Audio 5 Band equalizer using IC BA3812L
fan control circuit using ntc and tl082
cable tester uses quad latch
fm transmitter colpitt oscillator
22 Watt Audio Amplifier Circuit
Electronic Torricelli Barometer
Modular Signal System Implementation
GSM/GPS Localizer with SIM908 module
Peak Reading Audio Level Meter
The same capacitance parameters 12dB-oct low-pass filter