John Park in the Maker Shed: PIR Arduino motion alarm
Want to learn how to hook up a passive infrared (PIR) sensor to your Arduino? Check out this video I put together doing just that. These sensors are very nice to work with either by themselves (along with a transistor or relay) or on a microcontroller. You get about a 20 ft. range for detecting motion from humans, animals, other things that emit a decent amount of infrared radiation. WILL NOT DETECT THE UNDEAD