On Thu, 7 Aug 2008 10:42:01 -0400 "Rich" wrote: > If you design a 50-60 Hz sinusoidal generator and feed it to an op amp > and then to a complementary symmetry pair and take the output from the > common emitters, then, if you put the 120 VDC across the collectors > (PNP to the minus side) you should get 120 VAC output between the > collector of the PNP complement and the emitter junction. I am sure > that someone else will correct or add to this idea. You should be sure > to properly heat sink the output transistors because they will produce > a lot of heat. You'd get 85V AC. Remember AC is specified as RMS - so the peaks of AC are 1.41 times greater, and the input rectifier of the PS detects (and needs) those peaks. There's little need to generate sines at all - you could simply generate a square wave, so you wouldn't have problems with the output transistor dissipation. There are only two problems - 1) the PS would probably like 120VAC*1.41 = 160+V, and 2) as Bob pointed out, if the PC is more or less new, you will need the separate +5V. John -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist