[sdiy] Dual DC-Power from a single AC-supply

[Paul Schreiber]

Meh....I did that in 1980 in the Radio Shack MODEM I 300-baud modem :)

And I did it with only 3 discrete diodes.

Paul S.

----- Original Message ----- 
From: "np" <np at planetarc.de>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Saturday, May 02, 2009 7:54 AM
Subject: [sdiy] Dual DC-Power from a single AC-supply


> Hey!
>
> I recently had the problem to get a dual DC voltage from a single AC 
> transformer winding. I've asked around on the net and a old tube-guy 
> showed me a circuit that I haven't seen anywhere before.
>
> http://torus.untergrund.net/tubes/double_rectifier.png
>
> It's voltage doubling with two cascaded bridge rectifiers. I have built 
> the circuit and use it to power a OpAmp circuit. The power I get from this 
> rectification is of better quality than what I get with DC voltage 
> doublers/inverters (less hiss), and it has advantages over simple diode 
> voltage doubling:  I get less and higher frequency ripple. It's easier for 
> the transformer as both half-waves are used and you need less filtering.
>
> For the AC coupling-capacitors I use 470µF.  These work fine even if I 
> draw 50mA from each rail
>
> Since it works so well and only need three additional cheap parts  I 
> thought I'd post it here. Maybe the one or another can now put salvaged 
> 12V single supply trannies or AC wall-warts into better use..
>
> Cheers,
>  Nils
>
>
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