Let me introduce another simple microcontroller-based do-it-yourself circuit that detects motion and excites a light source in a flash. The “snooper” here is an ordinary passive infrared (PIR) motion ...

First let's discuss the hardware. The sensor selected for this design is the Glolab (www.glolab.com) PIR325 dual element pyroelectric sensor. There are a number of different PIR sensors available, ...