In hacking (thanks, Kyle) through getting both the script working (hey, had to modify it for my own install, which is a good thing...:)) and addressing the proper node/dongle number...and getting the parts to build the circuit (at Radio Shack, believe it or not...) as shown at the DMK site so I could actually drive my cooling fans (with 3 repeaters, a 100w amp, and batwing spectra transmitter that gets Real Toasty even at 12w out, the amount of constant noise is a bit much, even in the basement...not to mention the electricity consumption), it's all up and working. However, in talking with Scott KB2EAR, he brought up the issue of the possibility (not remote..) of the controller or a dongle hanging or going brain dead in between the time that the radio keys up and the fan controller script turns on the relay...with the possibility that the radio would key (along with the amp...) but the fans would never come up. So...belt and suspenders time. I have an extra box of shalco thermoswitches...NO contacts, close at 115c, reopen at 95c or thereabouts. Since the relay (I like electromechanical stuff, ok? Nothing like the sound of contactors closing all around the shack when you press one button...brings me back to the days of running BIG transmitters and the plate contactor closing when you pressed 'PLATE ON' and saw the plate voltage meter swing to 18KV @ 2.6A) that's being driven by the DMK circuit is actually controlling the B+ to the fan string...putting one of the thermo switches across the armature and NO contact of the relay...well, if the computer hangs, or the relay fails, and the transmitter and amps are up...when they get warm enough, the secondary mechanical (rather than logical) circuit takes over and STILL turns the fan on. I'd rather fail, if that's the scenario, with cooling flow across the heat sinks than not. Obviously, this implies that the logical circuit is driven from the same power supply as the fans (mine are...) to eliminate that issue. Anyway...wired that up as an addition to the relay circuit; actually, it's just a pair of wires coming back from the shalco and paralleled across the leads from the relay. Just throwing that out there for y'all's consideration, if you're building the circuit from DMK to do something like this. (Still have to mount the DMK circuit on perfboard in a small project box and clean up the wiring...right now, it's just hanging by its wires in front of the repeater shelving unit (plastic...one of those Sears 5-shelf organizers...). Final cost, by the by, of the DMK circuit, using bits and pieces from the Shack, was under $10 USD, btw. And the biggest cost was the big piece of perfboard (which I cut down, so I have lots extra to use for other projects) and the small DPDT relay. Bought the 10-pack of transistors, 10-pack of diodes, and couple sleeves of the 4.7K resistors, so, have some extras to build other interfaces... 73 -- Bryan In this world, you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant. You may quote me. Sent from my MacBook Pro.