Cool intercom addon to unlock front door
If you have an analog intercom in your apartment and feel bored every time you need to unlock the doors, this might be your next project!
It is an addition to your analog intercom which is installed in the apartment and is used to unlock the front door by entering a secret passcode. Of course, the passcode is not a traditional numerical one, it actually consists of short and long rings! To make project even more interesting and fun, the author added an audio playback option to play funny lines when wrong passcode is entered.
Entire project is open source so you can build one for yourself and even customize it more.
[ Source: Paweł ]