Day/Night sensor with 3hour delay?
I need to build a circuit for a friend. He has a billboard that needs to be lighted every night, but it needs to be lighted only for about three hours (until he closes shop).
The only problem is, there is no way to get mains power to the billboard, so we figured that we'd set a small 12v battery, solar cells, and some led tape, that would be enough.
Now all i need is a 12v circuit that would detect low-light conditions (night) and would turn on a timer which would turn off the whole circuit after 3 hours.
I searched the net and my local electronics stores, but couldn't find a circuit that would suit my needs...
So any help would be greatly appreciated!