(Passive InfraRed sensor) A device used to detect motion by receiving infrared radiation. When a person walks past the sensor, it detects a rapid change of infrared energy and sends a signal.

this DIY motion trigger for a DSLR is a quick and easy build, and probably loads more fun. The BOM on [Jeremy S Cook]’s build is extremely short – just a PIR sensor and an optoisolator ...

Jennifer Pattison Touhy has a story on The Verge today about a technology debuting soon that turns existing smart lights into motion sensors: Sensify is a proprietary technology based on wireless ...