[sdiy] Power supply for Big Briar Etherwave Theremin

[Roman Sowa]

If you have any AC source at hand around 11 .. 16V, then wire it 
yourself. There's no magic in original supply. Then connect GND with 
separate wire to earthing pin.

Roman

W dniu 2022-07-06 o 15:14, Peter Pearson pisze:
> 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 
> <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 
> <mailto: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>
> 
>      >
>     <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>
>      > <mailto: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>
>      >   
>       <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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