12volt

Here's what I would like to do, if you can help that would be great. When I disarm my car alarm I would like the headlights and backup lights to come on, that’s the easy part I know how to wire the relays. Here is the hard part. I only want this to happen when it is dark out so I want to use a photo sensor to power one side on the coil only when it is dark. I would ground the other side of the coil from my dome light relay in the alarm. So, in theory when ever I disarmed the alarm it would ground the coil of that relay, but the relay would only have power when dark by means of the photo sensor.  Then I would wire the relays to power the headlights and backup lights.

Any help any one could give on the best way to do this would be great. I am not sure on what all I would need to do this, just a photo sensor, what else?

I did some searching and found a few links that you'll probably find helpful......

  http://www.aaroncake.net/circuits/hdlights.htm