When the folks over at PinMeTo moved into a new office, they were dismayed to find out an extra key would run them a whopping 500 sek (~$75 USD). Instead, they decided to build their own automatic door lock using the Electric Imp system.
If you’re not familiar, the Electric Imp is a small SD card designed to provide internet (Wi-Fi) functionality to consumer devices. While it looks like an SD card, you cannot just plug it into any SD card slot and expect it to work — it still needs a prototyping board. We’ve seen it used to make a wireless thermal printer, or even make a tweeting cat door to let you know of any feline intruders!
Anyway — back to the hack. To move the lock cylinder they’re using a basic RC servo connected directly to the Imp. A flex sensor is installed on the side of the door over-top the lock — this provides feedback to the Imp whether or not the door is in fact locked. The Imp then communicates to Everymote to allow for keypad access from your mobile phone.
It probably ended up costing more in time and money than a new key, but hey, it looks like it was a fun project to do!