Re: PIR vs. Computers

["Stanley Barthfarkle" <sbarth@xxxxxxxxx>]

"shady" <sh@xxxxxx> wrote in message
news:1cKkf.234086$ir4.174815@xxxxxxxxxxx
> Just wondering if there's a risk of false alarms on a motion (DSC's BV300,
> not pet immune) which faces a computer about 12-15 feet away (blinking
> led's, screensavers, etc.)
>
> It's been good so far... just don't want to have any problems over
> Christmas when I'm gone.


A Passive Infrared detector looking at a computer isn't a problem, unless
the computer is on wheels and happens to roll across the room.  :-)

The LED's don't put off enough heat, and are too small anyway. The fan
should be constant, and the air volume is small, so that shouldn't be a
problem. Screensavers, or any "movement" on the screen is invisible to the
PIR, since it is looking for changes in Infrared background radiation, and
"motion" on the screen is invisible at Infrared wavelengths.

Think "Night Vision"- That's Infrared.