All: If anyone is looking for a very simple, temperature-dependent fan speed control, check this out: http://www.heatsink-guide.com/content.php?content=control.shtml It uses a 10k pot, NTC thermistor, MOSFET and 12v fan. I just built one using a 40mm Sunon fan for a small SBC enclosure and it works great. All parts (except the fan) are available from Radio Shack and cost about $7. Rich Rich Cini Collector of classic computers Lead engineer, Altair32 Emulator Web site: <http://highgate.comm.sfu.ca/~rcini/classiccmp/> http://highgate.comm.sfu.ca/~rcini/classiccmp/ Web site: http://www.altair32.com/ /***************************************************/