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basic split rail PSU
basic split rail PSU
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Old 28th January 2003, 02:31 PM   #1
mcai7et2 is offline mcai7et2
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Default basic split rail PSU

I am building a stereo power amp using boards from Avondale Audio. I have got to the stage where all I need is a PSU, a simple split rail, unregulated (for now) 50-0-50 (approx) power supply.

I am pretty sure that I am on the right track as to how to do this, but I would like confirmation before I start any fires. I am going to use a single discrete rectifier with Schottky diodes, a 700Va 2x40v toroid and two 22,000uf 63v capacitors.

Is there a simple circuit or guide online which will explain how to wire this up? I have found lots of complicated circuits for regulated PSUs but nothing to fulfill my simple needs.

Kind regards,

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Old 28th January 2003, 03:27 PM   #2
mcai7et2 is offline mcai7et2
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Default Found some

I have just found an excellent resource at TNT Audio, I would still welcome and guidance from the members here though:

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Old 30th January 2003, 02:40 AM   #3
NickC is offline NickC
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hey watch out for the Schottky diodes that can't take high voltage normally better get one with atleast 200v PIV(i think forgot the terminology here) or not stick with normal diodes and just bypass them with small caps diagram shown in the tnt audio
with 40-0 VAC u should get 40*1.41-1.4(assume silicon turn on voltage one diode is 0.7v and there are two diodes to account for, schottky i not sure) u would get above 50 volts
well good luck then, since this is your first ps supply go for bridge type, easy and good and don't forget that if your caps are big the diodes needed to be rated big also for current demand when turn on
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Old 30th January 2003, 05:24 AM   #4
Nelson Pass is offline Nelson Pass  United States
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basic split rail PSU
Look at any of the schematics for power supplies
at www.passdiy.com or elsewhere. They're pretty

Those Schottkys will need a 100 V rating for +-50 V

Maybe you want to try something more conventional
first time out, like a $3 bridge from Digikey.
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Old 30th January 2003, 09:27 AM   #5
RichardH is offline RichardH
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Location: Hertfordshire, UK
Have a look at the bottom of this page http://sound.westhost.com/project3a.htm - this should help.
I'm guessing you've bought the
Have you bought the modules complete, or just the boards? Be interested to hear how you get on sourcing the parts, if the latter - particularly if you're in the UK.
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Old 30th January 2003, 11:06 AM   #6
carlmart is offline carlmart  Brazil
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Default Power supply basics

There's a very good article on how to design your own power amp supply here:


Also talks about diodes/bridges quality you can use, as well as caps. An obligatory reading, in my opinion, from both a subjective and objective point of view.

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Old 30th January 2003, 12:10 PM   #7
mcai7et2 is offline mcai7et2
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The Schottky bridge is being bought as a pre built module, designed specifically for the amp modules. I am building the modules from bare boards, most of the parts have come from Farnell's, with Maplin contributing some resistors and other simple components.
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