Simple Car Alarm Arming Horn Beep Canceller Project

This is the Simple Car Alarm Arming Horn Beep Canceller Circuit Diagram Project. It's a great convenience that most modern cars come with a built in alarm, however it is nothing but noise pollution that the horn sounds when the alarm is armed. Disconnecting the alarm system from the horn relay will eliminate this, but prevent the horn from sounding in the even of an actual alarm. This circuit serves to silence the arming beep yet maintain the alarm by introducing a small delay into the signal. 

 

Car Alarm Arming Horn Beep Canceller Circuit Diagram

 

 

 

It sits between the alarm and horn relay. The alarm must provide a constant horn signal for at least 3 seconds before the horn relay is activated. That way the quick "beep" will never activate the horn relay, while the constant alarm signal will.


Part           Total Qty.             Description
C1                   1           0.01uF Ceramic Disc Capacitor  
C2                   1           100uF 35V Electrolytic Capacitor  
R1                   1           1K 1/4W Resistor  
R2                   1           10K 1/4W Resistor  
R3                   1           15K 1/4W Resistor  
R4                   1           470 Ohm 1/4W Resistor  
D1, D3, D4      3           1N4004 Rectifier Diode  
D2                   1           Red LED  
U1                   1           555 Timer IC  
K1                   1           SPST 12V Automotive Relay  
MISC               1          Board, Wire, Socket For U1, Case