I'm short one PIR (and our home haunt walk-thru opens friday) and happen to have a HC-SR501 PIR sitting around for an arduino-based project I won't get to this year. Aside from the pinout being different (middle pin is the output, left 5-20V and right is GND) should the PIR work on a PROP1 as a replacement for the parallax PIR?
Thanks,
Chris

I have a few of those, they should work similar to the Parallax PIR, especially if you use JonnyMac's PIR code.  You may have to play with the two knobs that control the settings.