DIY Digital Combination Clock
Ever wondered how a digital combination lock works?
Instructables member Nino123 is kind enough to demonstrate the inner workings, with a step-by-step HowTo on building your own.
"You can connect it to anything from 1v to 400v (or maybe more that depends on the RELAY), DC or AC, so you could use it to control another circuit, or even to electrify a fence! (please don't try that, really dangerous)…"