<html><body><div style="font-size: 12pt; font-family: "times new roman", "new york", times, serif; color: rgb(0, 0, 0);"><div>I used to have a Big Briar Theremin and often ran it on a two-wire extension cord. That obviously negates any "earth ground" on the pin.</div>
<div>I never had an issue with function, so maybe there are cases where an earth ground is essential... but I didn't find one.</div>
<div> </div>
<div>Harry Bissell</div>
<div> </div>
<div>
<div id="OLK_SRC_BODY_SECTION">
<div id="OLK_SRC_BODY_SECTION">
<blockquote style="margin: 0 0 0 .8em; border-left: 1px #ccc solid; padding-left: 1em;"><hr id="MESSAGE_DATA_MARKER"><strong>From: </strong>Peter <synth-diy@synth-diy.org><br><strong>To: </strong>Roman <modular@go2.pl><br><strong>Cc: </strong>synth-diy <synth-diy@synth-diy.org><br><strong>Date: </strong>Wednesday, 6 July 2022 9:21 AM EDT<br><strong>Subject: </strong>Re: [sdiy] Power supply for Big Briar Etherwave Theremin<br><br>
<div dir="ltr">
<div>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.</div>
<div> </div>
<div><a href="https://www.ebay.com/itm/303827582131?hash=item46bd88fcb3:g:9D0AAOSweuFf6gew" target="_blank" rel="noopener noreferrer">https://www.ebay.com/itm/303827582131?hash=item46bd88fcb3:g:9D0AAOSweuFf6gew</a></div>
<div> </div>
<div>I fail to see how this is a worse option than cutting a barrel plug AC adapter and wiring it up yourself.</div>
</div>
<br>
<div class="gmail_quote">
<div class="gmail_attr" dir="ltr">On Wed, Jul 6, 2022 at 4:55 AM Roman Sowa <<a href="mailto:modular@go2.pl" target="_blank" rel="noopener noreferrer">modular@go2.pl</a>> wrote:</div>
<blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left: 1px solid #cccccc; padding-left: 1ex;">Exactly, it must be "grounded" in a sense of "earthed", and not <br>"center-tap".<br>If you connect center-tap transformer there, it will not be grounded, it <br>will be floating. And also it will be very hot, because ground pin on <br>the socket is shorthed to one of AC pins.<br><br>You need a link from earth protect prong in your AC outlet to one end of <br>your supply.<br>It all becomes so clear when you look at power input schematics on page 4<br><br>Do what Gordon says<br><br>Roman<br><br>W dniu 2022-07-06 o 08:05, Peter Pearson via Synth-diy pisze:<br>> <a href="https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf" target="_blank" rel="noopener noreferrer">https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf</a> <br>> <<a href="https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf" target="_blank" rel="noopener noreferrer">https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf</a>><br>> <br>> Read page 8 of the service manual where it says - and I'm quoting here - <br>> "*WHY IS THE POWER ADAPTER GROUNDED?*"<br>> <br>> On Tue, Jul 5, 2022 at 7:04 AM Gordonjcp <<a href="mailto:gordonjcp@gjcp.net" target="_blank" rel="noopener noreferrer">gordonjcp@gjcp.net</a> <br>> <mailto:<a href="mailto:gordonjcp@gjcp.net" target="_blank" rel="noopener noreferrer">gordonjcp@gjcp.net</a>>> wrote:<br>> <br>> On Thu, Jun 30, 2022 at 02:41:07PM -0400, Peter Pearson via<br>> Synth-diy wrote:<br>> ><br>> <a href="https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf" target="_blank" rel="noopener noreferrer">https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf</a><br>> <<a href="https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf" target="_blank" rel="noopener noreferrer">https://manuals.fdiskc.com/flat/BigBriar%20Etherwave%20Service%20Manual.pdf</a>><br>> ><br>> > The schematic is here. A DC supply won't work. The theremin<br>> might be<br>> > fussy about grounding though, so you'll definitely want a<br>> center-tap on<br>> > your power adapter. I wouldn't recommend trying to cheat a<br>> barrel jack AC<br>> > power adapter in there.<br>> <br>> If you look at the power input circuit, there are only two<br>> connections. There's nowhere for a centre-tap to go.<br>> <br>> It's a simple transformer fed into a pair of half-wave rectifiers,<br>> same as the various crappy modular PSUs that are kicking around.<br>> <br>> Everyone is making this waaaaaaaaaaaaaaaaaaaaaaaaaaaaaay more<br>> complicated than it needs to be.<br>> <br>> A 15V transformer will be fine. It doesn't need a centre tap. <br>> Anything over 200mA will be fine.<br>> <br>> -- <br>> Gordonjcp<br>> <br>> _______________________________________________<br>> Synth-diy mailing list<br>> <a href="mailto:Synth-diy@synth-diy.org" target="_blank" rel="noopener noreferrer">Synth-diy@synth-diy.org</a> <mailto:<a href="mailto:Synth-diy@synth-diy.org" target="_blank" rel="noopener noreferrer">Synth-diy@synth-diy.org</a>><br>> <a href="http://synth-diy.org/mailman/listinfo/synth-diy" target="_blank" rel="noopener noreferrer">http://synth-diy.org/mailman/listinfo/synth-diy</a><br>> <<a href="http://synth-diy.org/mailman/listinfo/synth-diy" target="_blank" rel="noopener noreferrer">http://synth-diy.org/mailman/listinfo/synth-diy</a>><br>> Selling or trading? Use <a href="mailto:marketplace@synth-diy.org" target="_blank" rel="noopener noreferrer">marketplace@synth-diy.org</a><br>> <mailto:<a href="mailto:marketplace@synth-diy.org" target="_blank" rel="noopener noreferrer">marketplace@synth-diy.org</a>><br>> <br>> <br>> _______________________________________________<br>> Synth-diy mailing list<br>> <a href="mailto:Synth-diy@synth-diy.org" target="_blank" rel="noopener noreferrer">Synth-diy@synth-diy.org</a><br>> <a href="http://synth-diy.org/mailman/listinfo/synth-diy" target="_blank" rel="noopener noreferrer">http://synth-diy.org/mailman/listinfo/synth-diy</a><br>> Selling or trading? Use <a href="mailto:marketplace@synth-diy.org" target="_blank" rel="noopener noreferrer">marketplace@synth-diy.org</a><br>> </blockquote>
</div>
</blockquote>
</div>
</div></div></div></body></html>