Auto On/Off Light Circuit
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Auto On/Off Light Circuit
Being that I was frustrated that our car doesn't come with some of the finer things in life, like automatic lights, I decided to build my own.
I purchased all of these parts at my local radio shack for about 30 bucks.... They can be bought online for much cheaper (10 bucks)


I purchased all of these parts at my local radio shack for about 30 bucks.... They can be bought online for much cheaper (10 bucks)


Last edited by Rotary Rasp; Apr 29, 2007 at 10:52 PM.
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The circuit uses a photocell to trigger a time delay circuit. When the photocell senses dark, it samples for 10 seconds, then turns on the lights. When light is detected, the circuit samples for 6 seconds then turns the lights off. This on/off delay prevents false signals caused by trees and tall buildings. The circuit shuts down when the key is removed. There is also a delay that is activated when the lights are on, it keeps the fog lights on for a set amount of time after the key is removed. This time is adjustable from 0-60 seconds. This circuit only functions when the lights were previously on. The on/off sensitivity is also adjustable.


Photocell (light sensor)



Photocell (light sensor)

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Lastly, If you want to disable the annoying chime that is triggered when the key is in and the door is opened... unplug this connector. This does not affect any other buzzers or chimes.
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Hooking the circuit to the car is very easy. All I had to do is tap 4 wires and attach a ground. I grounded it to a bolt on the steering column. Directly under that are the three wires coming from headlight switch. Tapped one for the running, fog, and head lights. The last wire runs to any power source that is only on when the car is on. I used the cig lighter. As for as the circuit itself, I have a crappy hand drawn schematic that I made. If I get time this week I'll remake it on the computer.
your electronic projects never cease to amaze me...
ever put any thought into window/sunroof mods similar to what lurch and some have done? things like, auto close on all 3 when the alarm sets?
ever put any thought into window/sunroof mods similar to what lurch and some have done? things like, auto close on all 3 when the alarm sets?
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Originally Posted by paulmasoner
your electronic projects never cease to amaze me...
ever put any thought into window/sunroof mods similar to what lurch and some have done? things like, auto close on all 3 when the alarm sets?
ever put any thought into window/sunroof mods similar to what lurch and some have done? things like, auto close on all 3 when the alarm sets?
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503wtq Boosted Bimmer
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Oh man, this was soooo last year. 
If I were to do it again, or actually sell them, I think I'd modify the circuit some more. Most notably, I would replace the relays with transistors.
There are a few things I've learned since making this.

If I were to do it again, or actually sell them, I think I'd modify the circuit some more. Most notably, I would replace the relays with transistors.
There are a few things I've learned since making this.




