Figure 1 shows a way to control a light (or other 120-V ac appliance) with a passive-infrared (PIR) alarm sensor. The original concept was to turn a closet or shop light on whenever someone went into.

Detecting and measuring movement is an essential element for many industrial and commercial IoT applications – from lighting and security to assisted driving. Motion detection systems consist of a ...

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.