Automatic Headlight Delay

When the driver depresses pushbutton switch S1, timing capacitor C1 charges to 12 V and turns on transistor Q1, which drives power transistor Q2 into conduction. This, in turn, 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.

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