I have a question about designing a timer circuit. I have two LED's wired in series running at 18 mA on a 12VDC circuit. All I want is a way to have them stay lit for about 5 minutes after they loose their switched power. I know I have to supply them with a steady power and ground. I want to be able to turn them on with a switched power/ground and then when they loose that switched power/ground they stay lit for roughly 5 minutes. I was just wondering if there is some kind of simple chip or way of wiring them so that this is possible.