At 03:06 PM 6/2/2011, Oli Glaser wrote: >You have probably already seen it, but is this one any good? Seems to be >about the only option I could find on there that meets your specs. >http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=3DIRFIB7N= 50APBF-ND=20 > > Yeah - that was the first part I ran across. Then I found these: and This last device is in a plastic TO-247 package but I don't know if=20 there is exposed metal at the back of the device. Unfortunately, the=20 datasheet doesn't say. Part of the problem is that this is the front end of the project -=20 now I'm told that I may need as much as 150W dissipation. So - now=20 I'm looking for larger parts. The device will be operated in the linear region for use as a heating=20 device on a flat aluminum plate. Thus the large dissipation=20 requirement. Max temperature will be somewhere near 15C or so - this=20 device is simply used to keep the internal temperature of an outdoor=20 piece of equipment warm enough to stop it from failing because of=20 extreme cold. I plan to use a thermistor tightly coupled to the=20 aluminum plate to avoid excessive transistor temperature. Simple project, except for finding the insulated transistor! Many thanks! dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .