In article , Kony wrote:
Which is not entirely applicable, since plenty of
non-recorders are made of circuit boards, ICs & other
discretes, and some plastic. Cell phone and pager are two
quite common ones.

More to the point, since someone was talking about an
office-like setting, would be things like SCR (triode) dimmer switches
built into the walls of the room, for perfectly good reasons. The
phrase is "false positive", and if anything they're even more corrosive
of ones confidence in the usability of a detection system than are
false negatives.
(Had a bad week last week with a poison gas detector system
going off every couple of hours. Every false positive meant that I had
to kit up with the breathing apparatus and go to check the situation
out.)

--
Aidan Karley, FGS
Aberdeen, Scotland
Written at Sun, 15 Oct 2006 20:46 +0100, but posted later.