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Courtesy Light Delay For Cars

Simple circuit has an adjustable delay from 7-40s and fades the lights out at the end of the delay period. And the same circuit suits all cars.

By John Clarke

A courtesy light delay is a great feature for your car. It enables you to see to insert the ignition key and find your seatbelt when it is dark outside, without having to leave the door open.

However, many cars lack this feature, particularly older models. When the car door is opened, the cabin lights do light up but as soon as the door is closed, the lights go out. This happens just when you are about to get settled into the seat. Of course you can fumble around and find the interior switch but wouldn’t it be nice if the lights stayed on automatically for a short time instead?

And wouldn’t it be classy if the lights faded out at the end of the timing period instead of a sudden switch off?

Another feature that would be useful is to have the courtesy light(s) automatically switch off whenever the parking lights are switched on. This would allow you to drive off if ready to go, before the courtesy lights had timed out.

The final feature of this new design is its ease of installation. Past courtesy light delay circuits have presented real problems for installation because of the various wiring combinations for courtesy lights in modern cars.

In presenting this new design, we particularly wanted solve the connection problems presented by the popular "Electronics Australia" design from the April 1997 issue. This design needed to be built in one of four versions, meaning that it was a game of chance if the car’s wiring configuration was not known. By contrast, in our new design, the same circuit will work in all cases.

Main Features
  • Adjustable delay period from 7-40s
  • Lights fade out at end of time period
  • Courtesy lights switch off if parking lights switched on
  • No standby current drain from battery when lights are off
  • Universal circuit works with any 12V car system
  • Low parts count
  • Easy to install

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