As far as a motion detector, I was afraid that a bird landing on it or snow blowing by may trigger it. If I point it downward from the roof, might even a dog walking by trigger it? I don't know how sensitive those things are.
[This message has been edited by Vic (edited October 20, 2000).]
possums and deer set them off. (I doubt if birds would.)
Also, they only work in low light, so if you wanted to use one to power an alarm of some kind, it would only work at night.
I think it's still not a bad idea. Anyone who is about to steal something and has a light come on in their face isn't likely to stick around. You can use a flood light bulb that shines right on the spot.
Some of them can be set for a fairly narrow range, so the person or animal that sets it off would have to be in just the right place.
Motion detectors work on heat patterns, but cold is also a heat pattern. Some motions work on microwave technology, and some on a combination of both, and even others have both and a micro prossesor. Regaurdless none of these will do what you want without false alarms. What may work is an out door duel Beam. Less expensive would be a siamese coax cable. This is a cable used in CCTV installs, it has a pair of 18 gau wires running in the same insulation as the coax that could easily be tied to the dish as a tamper circut without any signal loss.