Michael Watterson wrote:
> Three IR LEDs on a horizontal bar, occasionally pulsed A -> B -> C
> then
> C -> B -> A, appropriate distance from PIR. Or possibly even three
> small Metal Oxide  resistors!

The PIR sensors I've worked with are not that sensitive to near IR LEDs.
They work, but you'd need them close.

LEBs (Light Emitting Bulbs) make great IR emitters that PIR sensors pick up
easily.  You don't need to run them at full voltage either.  If you can see
a orange glow, they're putting out plenty of IR.  Used that way, they last
pretty much indefinitely.  Unlike resistors, they are actually intended to
radiate.


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