That will result in about an 84VAC (RMS) output, which is just barely outside the range of most full range power supplies (90VAC minimum) I wonder if there's a telco (48V or 60V) ATX power supply inexpensively available? A dumb (ineffecient) buck regulator from 120VDC to 48VDC might not be a bad path. Another really old school method is to do mechanical voltage conversion - use the 120VDC to drive a motor, which drives an AC generator. Some control circuitry is required to drive the speed so the output is near 50-60Hz. Add a flywheel and you've got a few seconds of backup power too... You might be able to get a used solar power inverter that runs on 120VDC for not a lot of money. Chances are good you'd solve a whole bunch of conversion problems if you just got the right inverter off the bat - and you might save money by not having to buy specialized equipment. I doubt this is the only thing you want to run off the 120V batteries. I'm curious why you're using a 120VDC battery, though, it seems the 60VDC and 48VDC are a lot more common and therefore have inexpensive and efficient converters widely available. Can you change the battery to 160-170VDC? Then you can go straight to modified AC sinewave with a simple H bridge. -Adam On 8/7/08, 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. > > > ----- Original Message ----- > From: "Cedric Chang" > To: "Microcontroller discussion list - Public." > Sent: Thursday, August 07, 2008 3:20 AM > Subject: Re: [EE] affordable full range 20+4 ATX power supply that may work > on120V DC? > > > >> Or can anybody think of some tricks that may be applicable to make > >> any old > >> PS work on 120V DC? > > > > The PC power supplies I am playing with now, double the AC input > > voltage to 320VDC. > > They were very unhappy when I tried to run them at 160VDC. > > > > I think your cheapest solution is going to be obtaining a cheap > > converter. a) 120VDC to 120VAC or b) 120VDC to 320VDC > > The voltage regulation on solution b does not have to be very good. > > > > cc > > -- > > http://www.piclist.com PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- EARTH DAY 2008 Tuesday April 22 Save Money * Save Oil * Save Lives * Save the Planet http://www.driveslowly.org -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist