How can I make a motion detector?

Question

How can I make a motion detector, from two cellphones, a floodlight, and a few other things? think third episode of Burn notice, where Michael had it rigged to set off the cell phone so he could tell when something was wrong. Anyone know how to make one?

Answer 1

Look for a kit at Radio Shack, or try one of these sources:

http://search.yahoo.com/search?ei=utf-8&fr=slv8-msgr&p=motion%20detector

Some of these products sell for as little as $30.