[sdiy] Power supply for Big Briar Etherwave Theremin

[Peter Pearson]

I looked at Didier's pic and yes the center pin specifically says "earth
ground".  I'll admit that I got out in the weeds here, however the ebay
link I had sent earlier also says GND on the center pin and has the added
benefit of already being a DIN plug.

https://www.ebay.com/itm/303827582131?hash=item46bd88fcb3:g:9D0AAOSweuFf6gew

I fail to see how this is a worse option than cutting a barrel plug AC
adapter and wiring it up yourself.

On Wed, Jul 6, 2022 at 4:55 AM Roman Sowa <modular at go2.pl> wrote:

> Exactly, it must be "grounded" in a sense of "earthed", and not
> "center-tap".
> If you connect center-tap transformer there, it will not be grounded, it
> will be floating. And also it will be very hot, because ground pin on
> the socket is shorthed to one of AC pins.
>
> You need a link from earth protect prong in your AC outlet to one end of
> your supply.
> It all becomes so clear when you look at power input schematics on page 4
>
> Do what Gordon says
>
> Roman
>
> W dniu 2022-07-06 o 08:05, Peter Pearson via Synth-diy pisze:
> >
> https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf
> > <
> https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf
> >
> >
> > Read page 8 of the service manual where it says - and I'm quoting here -
> > "*WHY IS THE POWER ADAPTER GROUNDED?*"
> >
> > On Tue, Jul 5, 2022 at 7:04 AM Gordonjcp <gordonjcp at gjcp.net
> > <mailto:gordonjcp at gjcp.net>> wrote:
> >
> >     On Thu, Jun 30, 2022 at 02:41:07PM -0400, Peter Pearson via
> >     Synth-diy wrote:
> >      >
> >
> https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf
> >     <
> https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf
> >
> >      >
> >      > The schematic is here.  A DC supply won't work.  The theremin
> >     might be
> >      > fussy about grounding though, so you'll definitely want a
> >     center-tap on
> >      > your power adapter.  I wouldn't recommend trying to cheat a
> >     barrel jack AC
> >      > power adapter in there.
> >
> >     If you look at the power input circuit, there are only two
> >     connections.  There's nowhere for a centre-tap to go.
> >
> >     It's a simple transformer fed into a pair of half-wave rectifiers,
> >     same as the various crappy modular PSUs that are kicking around.
> >
> >     Everyone is making this waaaaaaaaaaaaaaaaaaaaaaaaaaaaaay more
> >     complicated than it needs to be.
> >
> >     A 15V transformer will be fine.  It doesn't need a centre tap.
> >     Anything over 200mA will be fine.
> >
> >     --
> >     Gordonjcp
> >
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