In the microcontroller era today, Arduino is more than just a tool to accomplish hobby tasks. There is actually a close relationship between microcontroller technology and home security, since you can ...

[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 ...

A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors.

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.

Unlike infrared optical sensors that use an LED transmitter and IR receiver, the PIR emits nothing. As its “passive” name suggests, it responds only to infrared energy radiated by the object being ...