Car Alarm Arming Horn Beep Canceller
Electronic Schematics > Automotive > Car Alarm Arming Horn Beep Canceller

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. 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.

Schematic for Car Alarm Arming Horn Beep Canceller
Car Alarm Arming Horn Beep Canceller circuit

Parts
Part Total Qty. Description Substitutions
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 Boar

Title: Car Alarm Arming Horn Beep Canceller
electronic circuit
Source: unknown
Published on: 2012-09-20
Reads: 115
Print version: Print version

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Electronic circuits > Automotive > Car Alarm Arming Horn Beep Canceller