Can anyone suggest a good place to order standard logic ics to do the sort of very low switching speed requirement things needed in projectors, like AND together a signal from an attic thermostat and an on/off switch? Any suggestions on what to look for (input levels, package sizes, etc.)?

Thanks!

Just wire the attic switch and power switch in series with the coil of a relay.
I'll assume you have a 12VDC wall wart and a relay with a coil of the same voltage.

(12VDC positive) +-------> power switch <-------> attic switch <-------> 12VDC relay coil <------ -(12VDC negative)

Other voltages may used also as long as the wall wart voltage matches the required relay coil voltage.

It's been a long time since I've had to order parts such as this online but I recall these sources.
MCM Electronics, Parts Express, Mouser, and Radio Shack.

Hey Pal what is a wart????

Guess that's an Americanism. Those small AC or DC power supplies that plug directly into a wall receptacle that appear to be a black
wart growing out of the wall. You probably have a box of them sitting around somewhere from old modems and such.

ahhhhh,,, that one has escaped me,,,, we call them battery eliminators,,

plug paks etc etc

That makes way more sense than the unnecessarily complex tangle of voltage dividers and ICs I was conjuring up in my head. Wire in series for an AND, in parallel for an OR. Thanks for diverting a time-wasting wiring adventure with a little common sense