On Thu, 30 Dec 2004 11:11:39 +0800, Old Nick
wrote:

On Wed, 29 Dec 2004 08:17:53 -0800, Winston
vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

Just a question about this. How then can a spider or spider web set it
off? This apparently is a common cause of false alarms....

The only way a spider can set off a "zoned" PIR is by crawling around
on either the circuit board, or the detector itself in the reflector
element. Spider webs cannot set off a PIR unless the web is the
consistency of a cargo net.

Gunner


Any infrared sensor relies on a sharp contrast in heat level between
'person there' and 'person not there'. You get that from exposed skin,
not by sensing tiny temperature differences on the surface of an
insulated jacket.

--Winston

"War is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and patriotic feeling
which thinks that nothing is worth war is much worse. The person who has nothing for which he is willing to fight,
nothing which is more important than his own personal safety, is a miserable creature and has no chance of being
free unless made and kept so by the exertions of better men than himself."
- John Stewart Mill