[ladyada] has a freshly-published and amazingly thorough tutorial on passive infrared (PIR) motion sensors. Most often seen in security floodlights and automatic doors, in creative hands these sensors ...

Moderately priced Passive Infrared PIR Sensor modules are now widely available. By using these readymade and pre-configured PIR sensors, even an average electronics hobbyist can construct his/her own ...

Recently, I exhausted my stock of common passive infrared (PIR) motion sensor modules and was looking for a new one to play with. I searched the web for a small type with self-contained electronics.