<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Also look at the schematic, and notice that the ground pin on the PSU connector is connected to one of the AC supply pins. Connecting the CT of a transformer to the GND pin will result in one side of the secondary being shorted.<div class=""><br class=""></div><div class=""><br class=""></div><div class="">Phil.<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 6. Jul 2022, at 09:05, Peter Pearson via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" class="">synth-diy@synth-diy.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class=""><a href="https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf" class="">https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf</a></div><br class=""><div class="">Read page 8 of the service manual where it says - and I'm quoting here - "<b class="">WHY IS THE POWER ADAPTER GROUNDED?</b>"</div></div><br class=""><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Jul 5, 2022 at 7:04 AM Gordonjcp <<a href="mailto:gordonjcp@gjcp.net" class="">gordonjcp@gjcp.net</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On Thu, Jun 30, 2022 at 02:41:07PM -0400, Peter Pearson via Synth-diy wrote:<br class="">
> <a href="https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf" rel="noreferrer" target="_blank" class="">https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf</a><br class="">
> <br class="">
> The schematic is here. A DC supply won't work. The theremin might be<br class="">
> fussy about grounding though, so you'll definitely want a center-tap on<br class="">
> your power adapter. I wouldn't recommend trying to cheat a barrel jack AC<br class="">
> power adapter in there.<br class="">
<br class="">
If you look at the power input circuit, there are only two connections. There's nowhere for a centre-tap to go.<br class="">
<br class="">
It's a simple transformer fed into a pair of half-wave rectifiers, same as the various crappy modular PSUs that are kicking around.<br class="">
<br class="">
Everyone is making this waaaaaaaaaaaaaaaaaaaaaaaaaaaaaay more complicated than it needs to be.<br class="">
<br class="">
A 15V transformer will be fine. It doesn't need a centre tap. Anything over 200mA will be fine.<br class="">
<br class="">
-- <br class="">
Gordonjcp<br class="">
<br class="">
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</blockquote></div>
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