[sdiy] Power Supply Question

[harrybissell]

Center tapped wall warts DO exist... although they are as rare as the proverbial
noiseless vinyl zzzzzzzzz ........

<bfg>

H^) harry

Scott Gravenhorst wrote:

> "Ray Wilson" <raywilson at comcast.net> wrote:
> >Does anyone have a circuit idea (schematic, web-page, etc) that shows how to
> >use a wall wart to get a + and - 9V supply at about 50 to 100 mA per side?
> >Do they make dual supply wall warts? Do they make wall warts with center
> >taps?
> >
> >Any help appreciated.
>
> Wow, what a relief from the analog better, no digital better, no vinyl
> better, no CDs better...  I broke my delete key on that one.  Whew.  So thank
> you for this,  a REAL SYNTH-DIY question!
>
> I've not seen center tapped wallwarts, but I suppose they could exist.
>
> The current demand you need isn't large, so you may be able to do it by using
> two halfwave rectifier circuits from one non center tapped wall wart.  This
> is exactly how it's done in the FatMan (see schematic at www.paia.com).  In
> fact, the FatMan supply has 3 regulated outputs for +5, +8 and -12.  One
> halfwave circuit provides that + raw voltage, so it's diode will be one way,
> the other diode which is reversed will produce the negative raw supply.  The
> other transformer conductor is the system's common or ground.  You'll want to
> make sure the filter caps are big enough, but again, 100 ma isn't that much
> and should be easy to do.  In the case of the FatMan, as 12 volt transformer
> is used.  I think you'd want to find a 9 volt transformer, and you'll want to
> regulate the output voltages.
>
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