Tom Pappano wrote:

The previous tennant of my office left behind a passive infrared
detector from his security system. I probably can integrate that into
the system as well, and adding a pot to set "turn off delay" will
give you an "auto start with time delayed off" function.

The detectors I've seen used in security systems have been low voltage units. If
you need 110v, the heat/motion detectors used for outdoor lights work well and
can be purchased separately from the lights. These usually have primitive adjustable
timers. Many of them also have photocells to keep them from operating during the
day, so, if you go this route, disable that.

George Patterson
Great discoveries are not announced with "Eureka!". What's usually said is
"Hummmmm... That's interesting...."