Circuit Diagram Automatic Headlight Schematic Board
This circuit shows the timing capacitor C1 charges to 12 V and turns on transistor Q1, which drives power transistor Q2 into conduction.
Then it will energizes the relay which has its contacts connected in parallel with the headlight switch.
The relay will stay energized until C1 discharges to the Q1 turn-off level.
The lights-on period is determined by the value of C1, R1, and the characteristics of transistor Q1. With values chosen on the schematic, about 60 light-on seconds are provided.
Part list of Automatic Headlight Circuit diagram
C1 - 500uf electrolytic capacitor 15vdc or better
Ry1 - Relay DPDT, 10amp contact, 12VDC coil resistance
R1 - 300ohms, 1/2 watt resistor
R2,R3 - 560 ohms 1/2 watt resistor
Q1 - 2N1302 NPN transistor
Q2 - RCA4025 PNP transistor
S1 - Pushbutton switch normally open SPST