[sdiy] Power supply for Big Briar Etherwave Theremin

Peter Pearson electrocontinuo at gmail.com
Thu Jun 30 21:18:19 CEST 2022


Those are all DC supplies from the looks of it.  They're also barrel plug
without a center tap.  You'll want a center tap.

And yes, you're basically looking at a transformer that plugs in the wall
on one end and has a cable going to your synth on the other.  If you've
ever cracked one open, you'll see that that's what's inside the box part.

https://www.youtube.com/watch?v=ue1-lnHVkpQ&ab_channel=FRY524

On Thu, Jun 30, 2022 at 3:11 PM brianw <brianw at audiobanshee.com> wrote:

> Yes, they're still making them. Look for Triad Magnetics on Mouser.com
>
>
> https://www.mouser.com/c/power/power-supplies/plug-in-ac-adapters/wall-mount-ac-adapters/?m=Triad%20Magnetics&number%20of%20outputs=1%20Output&output%20voltage-channel%201=13.5%20V~~15%20V&instock=y&rp=power%2Fpower-supplies%2Fplug-in-ac-adapters%2Fwall-mount-ac-adapters%7C~Output%20Voltage-Channel%201
>
> I recently designed a phono (turntable) preamp, and I wanted to have a
> bipolar supply while avoiding 120 VAC. The AC output Triad Magnetics
> products work well. They have a wide variety of output voltages, and I
> bought an assortment to use with power supply design variations.
>
> They don't seem to have 14 VAC exactly ... only 13.5 VAC and 15 VAC. You'd
> have to look at the specific components in the Theremin to see whether
> either would be compatible (e.g. maximum voltage ratings, potential
> consequences of under-voltage, etc.).
>
> Brian Willoughby
>
>
> On Jun 30, 2022, at 11:58 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
>
> +1 agree. An "AC supply" in this case is called a "transformer", surely?
>
> I know they're a bit out of fashion, but I *think* they're still making
> them, so it can't be that hard to find one that'll get you from your local
> mains voltage to 14VAC. 200mA is basically nothing, so that's not going to
> be the hard bit. It looks like it needs a centre-tapped output, but those
> are common too, so it isn't difficult.
>
> HTH,
> Tom
>
> On 30 Jun 2022, at 18:56, brianw <brianw at audiobanshee.com> wrote:
>
> I may be oversimplifying, but the vast majority of AC output "supplies"
> are nothing more than a transformer.
>
> If you live in the 220 VAC 50 Hz part of the world, then you'll need a
> transformer rated for 200 mA that can convert 220 VAC to 14 VAC.
>
> If you live in the 120 VAC 60 Hz part of the world, then you'll need a
> transformer rated for 200 mA that can convert 120 VAC to 14 VAC.
>
> It's possible to design a power supply circuit that actually generates a
> 14 VAC sine wave at the proper frequency, with 3 W of output power, but I
> somehow find it doubtful that Big Briar did that. The Apple II power supply
> was renowned for synthesizing a 60 Hz wave, with feedback to increase or
> decrease the frequency depending upon the correct output voltage. This is
> why the Apple II made an audible chirp when the power switch was flipped.
> But that power supply was a lot larger than the Etherwave, and certainly
> more expensive.
>
> Brian
>
>
> On Jun 30, 2022, at 10:10 AM, Didier Leplae wrote:
>
> I would imagine what’s indicated on your power supply must be correct. I
> also found another image online of a power supply and it had the same
> pinout. Perhaps the schematic has an error or perhaps there was another
> version. I should be able to open up the theremin and see if pins 2 and 3
> are both connected to ground.
>
> Now, does anyone have a suggestion for building a 14vac 200ma power
> supply? Or if I could find something with those specs I could put a 5pin
> din connector on it
>
> On Jun 30, 2022, at 11:33 AM, Ben Stuyts <ben at stuyts.nl> wrote:
>
> Oh bummer. Let me know if you want me to actually measure it.
>
> Ben
>
> On 30 Jun 2022, at 18:00, Didier Leplae <didierleplae at yahoo.com> wrote:
>
> Interesting because the pinout shown on your power supply is different
> than indicated in the schematic in the manual on fdiskc. There pin 1 is
> connected to power and pin 2&3 are connected to ground. I wonder if that
> means there were different versions?
>
> On Jun 30, 2022, at 10:43 AM, Ben Stuyts <ben at stuyts.nl> wrote:
>
> Here’s a photo of mine. Funny, the MIDI warning on the label.
>
> The connector on my Etherwave is a 5-pin connector, so the power plug can
> be either 3-pin or 5-pin.
>
> Ben
>
> <PSU_Etherwave.jpeg>
>
> On 29 Jun 2022, at 22:46, Didier Leplae via Synth-diy <
> synth-diy at synth-diy.org> wrote:
>
> I have an opportunity to buy a Big Briar Etherwave Theremin from a friend
> for cheap. The only problem is it is missing the power supply.
> Searching online, I find a lot of Moog Etherwave power supplies.
> Does anyone happen to know if these are compatible?
> The power plug on the Big Briar unit is a 5-pin midi style plug.
> Pictures of the Moog power supply look like 3 pins.
>
> https://www.bigcitymusic.com/products/power-supply-115v-us-for-etherwave-theremin
>
> I’m wondering if they just simply removed two pins and the three fit in
> the midi style plug.
> If not compatible, does anyone know where to get a hold of the Big Briar
> supply?
>
>
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