Car Headlight Alarm

Here is the circuit diagram of car headlight alarm. This device can be set for one or two functions:
First, to indicate that the head lights (or the side lights) should be switched off after switching off the ignition contact. With this circuit, there should be no dead battery due to headlights that were left on.
Second, to indicate that the head lights should be on once ignition contact is switched on.

Car Headlight Alarm circuit diagram

Components List:

D1,D2,D3,D4,D5,D6,D7 : 1N4148
D8,D9                : 1N4007
ZD1                  : 2V4
R1,R2,R3,R4          : 47K
R5                   : 220K
R6,R7                : 470
R8,R9                : 10K
R10                  : 1M
C1                   : 100nF
C2,C3,C4,C5,C6       : 22uF/16V
C7                   : 470uF/16V
T1                   : BC547B
IC1                  : CD40106
IC2                  : CD4070
Buz1                 : Buzzer


Car Headlight Alarm Features:

  • Continuously repeated alarm tone for lights ON (may be disabled)
  • Repeated alarm tone for lights OUT
  • Only 3 wires are required for hook-up

This circuit come from Velleman product kit. Download the kit manual of Velleman car headlight alarm from the following link:


You may purchase the kit from electronic online store.