I used a pressure switch off of a household well water pressure tank. Got it at the local plumbing supply store. I used a pressure switch that turns the compressor on at 40 psi and off at 60 psi. For now it is hooked up to a little compressor that came inside of one of those roadside assistance kits, but I'll save some pennies until I can afford a "real" 12v compressor. But that's the fun of this hobby - making stuff work using whatever (safe) means possible.
That original box and instructions is way cool too.
Craig
