This design is a case for a digital programmable timer relay, which turned out to be a handy little tool. You can use it to turn electrical devices (AC or DC) on and off at programmable intervals, or when activated by a switch. I used it for programming a time delay into a vapor polishing chamber project.

Specs: Relay Type : SRD-12VDC-SL-C Input Power: 12VDC Switchable Load: 10A, AC 250V/125V, DC 30V max; Size: 60 x 40x 20mm/ 2.4" x 1.6" x 0.8" ~$15 sold on Amazon here: http://amzn.to/1VMUb8a

See images for directions on using the timer.