[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 ...

I recently had to build an infrared close proximity sensor that could tell if something was dropped in a parcel delivery drop box. After some searching, I ended up using a microcontroller and a piece ...

This is an Infrared beam breaking alarm ideal to use in entry or passages.It is based on the working of the popular IR sensor Module TSOP 1738 which senses 38 kHz Infrared pulses from the IR LED of ...