IR sensors rely on an emitter (IR LED) and a detector (photodiode or photoresistor) to measure infrared light and convert it ...

The presented schematic shows how to build a simple PIR motion sensor. PIR sensors allow motion sensing, it is almost always used to detect whether someone has moved in or out of the sensors range.

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.

Movement-based lighting suggests activity inside, which helps deter opportunists. Automatic light on stairs, landings and entrances reduces falls and avoids leaving circuits on. Hands-free access ...