On 06/02/2011 03:03 PM, Dwayne Reid wrote: > 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=3DIRFIB= 7N50APBF-ND >> >> > 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 > there is exposed metal at the back of the device. Unfortunately, the > datasheet doesn't say. > > Part of the problem is that this is the front end of the project - > now I'm told that I may need as much as 150W dissipation. So - now > I'm looking for larger parts. > > The device will be operated in the linear region for use as a heating > device on a flat aluminum plate. Thus the large dissipation > requirement. Max temperature will be somewhere near 15C or so - this > device is simply used to keep the internal temperature of an outdoor > piece of equipment warm enough to stop it from failing because of > extreme cold. I plan to use a thermistor tightly coupled to the > aluminum plate to avoid excessive transistor temperature. > > Simple project, except for finding the insulated transistor! > > Many thanks! > > dwayne > I may be showing my ignorance here, but why not use something *designed*=20 as a heating element? Or at least a simple cement power resistor? -Pete --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .