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From: mkr5000 on 30 Sep 2009 11:55
I've never used a "voltage inverter" -- I see that Maxim makes a chip
that will convert +5v to -5v and I would imagine
they can be used in a dual polarity supply.

However, I want to build an audio power amp supply for an LM3886 --
wonder if there's a chip or circuit that will
do the same thing at higher voltages (+ and - 30v -- even higher
maybe).

Always used a center tap transformer for this but was wondering about
the creative use of a single secondary
transformer.

Or should I stick to the conventional dual winding approach? (I do
hate potential problems).

Thanks.
From: Phil Hobbs on 30 Sep 2009 12:03
mkr5000 wrote:
> I've never used a "voltage inverter" -- I see that Maxim makes a chip
> that will convert +5v to -5v and I would imagine
> they can be used in a dual polarity supply.
>
> However, I want to build an audio power amp supply for an LM3886 --
> wonder if there's a chip or circuit that will
> do the same thing at higher voltages (+ and - 30v -- even higher
> maybe).
>
> Always used a center tap transformer for this but was wondering about
> the creative use of a single secondary
> transformer.
>
> Or should I stick to the conventional dual winding approach? (I do
> hate potential problems).
>
> Thanks.

How about a full-wave voltage doubler? Ground one end of the secondary,
connect A of one diode and K of the other to the other end. Makes two
half-wave rectifiers of opposite polarity, total voltage ~2.5 to 2.8 x
VRMS.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
From: George Herold on 30 Sep 2009 12:46
On Sep 30, 12:03 pm, Phil Hobbs
<pcdhSpamMeSensel...(a)electrooptical.net> wrote:
> mkr5000 wrote:
> > I've never used a "voltage inverter" -- I see that Maxim makes a chip
> > that will convert +5v to -5v and I would imagine
> > they can be used in a dual polarity supply.
>
> > However, I want to build an audio power amp supply for an LM3886 --
> > wonder if there's a chip or circuit that will
> > do the same thing at higher voltages  (+ and - 30v  -- even higher
> > maybe).
>
> > Always used a center tap transformer for this but was wondering about
> > the creative use of a single secondary
> > transformer.
>
> > Or should I stick to the conventional dual winding approach?  (I do
> > hate potential problems).
>
> > Thanks.
>
> How about a full-wave voltage doubler?  Ground one end of the secondary,
> connect A of one diode and K of the other to the other end.  Makes two
> half-wave rectifiers of opposite polarity, total voltage ~2.5 to 2.8 x
> VRMS.
>
> Cheers
>
> Phil Hobbs
>
> --
> Dr Philip C D Hobbs
> Principal
> ElectroOptical Innovations
> 55 Orchard Rd
> Briarcliff Manor NY 10510
> 845-480-2058
> hobbs at electrooptical dot nethttp://electrooptical.net- Hide quoted text -
>
> - Show quoted text -

Phil are you sure you get the doubling effect AND two polarities?

you mean a circuit like this,
http://www.play-hookey.com/ac_theory/ps_v_multipliers.html

But most likely I just misunderstood.

George H.

From: mkr5000 on 30 Sep 2009 12:50
You mean just like a simple half wave with another rectifier in
parallel but reversed?

I never tried that -- didn't even think of it ! -- (or have even seen
it in many schematics
for that matter). (Of course, I wasn't looking for it, so maybe that's
the reason).

I'll be darn -- except for the ripple compared to a bridge, it will do
the job just as well?

Is it a good idea to match the rectifiers as far as forward and
reverse resistance?

Using an over rated diode in a half wave is always a good idea too,
isn't it?

Thanks.

From: Jan Panteltje on 30 Sep 2009 13:16
On a sunny day (Wed, 30 Sep 2009 09:50:44 -0700 (PDT)) it happened mkr5000
<mikerbgr(a)gmail.com> wrote in
<8642149e-b1a9-4cbf-851a-bab6e9c499b5(a)p23g2000vbl.googlegroups.com>:

>You mean just like a simple half wave with another rectifier in
>parallel but reversed?
>
>I never tried that -- didn't even think of it ! -- (or have even seen
>it in many schematics
>for that matter). (Of course, I wasn't looking for it, so maybe that's
>the reason).
>
>I'll be darn -- except for the ripple compared to a bridge, it will do
>the job just as well?
>
>Is it a good idea to match the rectifiers as far as forward and
>reverse resistance?
>
>Using an over rated diode in a half wave is always a good idea too,
>isn't it?
>
>Thanks.

My bass amp:
http://panteltje.com/panteltje/amplifier/sch_lay.pdf
From:
http://panteltje.com/panteltje/amplifier/index.html


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