This article describes how I have set up a simple “door-sentry” at home. The door-open detector is designed to alert you to an unauthorized entry in a confined area. It uses a little ATtiny85 ...

[Andrea] just sent us this great student hack he made for his room. He’s constructed an Arduino keypad door lock — without using any proper fastening hardware! The entire build is made out of scrap ...

This compact and affordable door sensor mechanism uses a Hall-effect sensor fixed at the corner of the door frame and a standard bar magnet fixed on the door panel close to the Hall-effect sensor.