[Colin Merkel] had a little problem: he was continually forgetting his electronic key card, locking himself out of his own dorm room. Like any normal Hack a Day reader, rather than getting in the habit of always carrying his card, the natural impulse of course is to build this elaborate rig of electronics and duct tape. Right?

The result is an additional keypad that can be used to gain access…not by altering the existing electronic lock, but with a secondary mechanism that operates the inside door handle. An 8-bit PIC microcontroller scans the outside keypad (connected by a thin ribbon cable), and when a correct access code is entered, engages a 12 volt DC motor to turn the handle. It’s a great little writeup that includes a parts list, source code, and explains the process of keypad scanning.

It’s similar to the RFID-based dorm hack we previously posted. By physically operating the handle, most any approach could be used: facial recognition, other biometrics, DDR pad, or whatever inspired lunacy you can dream up.