jrn@booth.uucp (Jim Norton) (05/22/91)
Hi everyone! A friend and I are designing a Pulse Width Modulation Amplifier that will pump out 800 watts ( 200 watts / 4 channels) and have come up with some specifications for the whole circuit. (assuming 8 ohm speakers for load) It seems obvious that we need a power supply that can put out 40 Volts at 20 Amps and be highly filtered. Does anybody know how to build such a beast of a power supply? Is it possible to buy one? If so how much? Has anybody got any schematics? Any know where is the best place to get these higher power handling diodes and capacitors? We need any help that people can offer..... We have the rest of the amplifier designed.... Just need the power supply now.... :-() Thank you! ====== jrn@booth.UUCP (Jim Norton)
mcarrick@gara.une.oz.au (Mick Carrick) (05/23/91)
From article <1991May22.060038.20285@booth.uucp>, by jrn@booth.uucp (Jim Norton): > > Hi everyone! > > A friend and I are designing a Pulse Width Modulation Amplifier that will > pump out 800 watts ( 200 watts / 4 channels) and have come up with some > specifications for the whole circuit. (assuming 8 ohm speakers for load) > > It seems obvious that we need a power supply that can put out 40 Volts at > 20 Amps and be highly filtered. > > Does anybody know how to build such a beast of a power supply? Is it possible > to buy one? If so how much? Has anybody got any schematics? Any know where > is the best place to get these higher power handling diodes and capacitors? > > We need any help that people can offer..... We have the rest of the amplifier > designed.... Just need the power supply now.... :-() In Audio Amateur 1/1980, James Boak published a low impedance regulated power supply that I have successfully modified to allow 15 Amp @ 70 V output. Just use heavier pass transistors and modify a couple of resistors and capacitors as suggested by Boak. A followup note by Walt Jung contained suggested modifications which are well worth including. The power supply is quite robust. In testing a power amp using these supplies, I accidently used a 0.2 Ohm resistor across the output instead of 200 Ohms, causing about a 70 Amp current to be drawn. The output track (1/4 inch wide) on the board vaporized but the rest of the supply survived. I was quite impressed. If you can't find the articles mentioned, email me about it. I am currently trying to find some reasonable PC board design software preferably on a Mac, to redesign the very clutzy board I am now using, so can't offer a sensible board design at present. I think back issues of Audio Amateur can be ordered from PO Box 576, Peterborough, NH, 03458, USA. Good luck with your beast Mick Carrick q s A A A