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 ...

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.

An Arduino is a microcontroller — a single board designed to control something and perform a specific task. Unlike a ...