Elysian Theremin Power Supply

Do you think there is a more portable option?

Kalib said: Do you think there is a more portable option?

It says it weighs 4.3 lbs, I am sure you could pick that up.

Do you want something you can put in your shirt pocket?

Won't happen because using a heavy transformer is the best approach for you.

In my own design, I solved all theremin issues, I took into consideration the need to use any type of power supply.

With theremins earth-ground is very important, difficult to explain to on the floor wrap cable around me experts.

Christopher

Kalib, if you have 19VDC unregulated and want 15V regulated just buy a 7815 and stick it in there.  If it gets hot put a small heat sink on it.  If you put the 7815 in the Theremin cabinet itself it will also help protect the rest of the circuitry from overvoltage and such.  Good voltage regulation is essential to keeping drift low.

If you have a switching supply hanging around that can do 15V give it a try, all the gloom and doom people say about not being able to use them with Theremins may not be true for your particular case.  Even if it is noisy, you may be able to filter that out as it is usually fairly high frequency.

Regardless, you will need a good ground.  I did some experiments a while ago, and as long as the ground is through a small enough resistance, or a large enough capacitance (0.01uF IIRC), then it should work.  A wire straight to AC ground is the blameless solution, you've done all you can short of grounding your body.  I haven't tried a wire on the floor (don't know how Christopher got it in his head that I had) but if it works it's because the capacitance to ground is large enough.

Hi All,

Unfortunately using a grounded power supply (Tekpower Linear Power Supply 15V @ 2A, TP1502D, Digital Display $45) didn't resolve the no volume control or audio out the speaker or headphone jack. In fact it shifted the pitch control in a way that Null could no longer be found at 2 o'clock as I could with the ungrouned power supply! https://www.amazon.com/gp/product/B015H0UPWU/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 Pitch just goes to low to the left, high to the right now. Was hoping the lack of ground was the root cause. Oh, well.

I can confirm that the pitch antenna's responsiveness and accuracy if far superior to the Etherwave or Theremini. It was much easier to find notes by adding extended fingers in sequence. Seemed more linear too. So, this might still be worth exploring.

K

"Unfortunately using a grounded power supply (Tekpower Linear Power Supply 15V @ 2A, TP1502D, Digital Display $45) didn't resolve the no volume control or audio out the speaker or headphone jack. In fact it shifted the pitch control in a way that Null could no longer be found at 2 o'clock as I could with the ungrouned power supply! https://www.amazon.com/gp/product/B015H0UPWU/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 Pitch just goes to low to the left, high to the right now. Was hoping the lack of ground was the root cause. Oh, well."  - Kalib

This is what you get when you don't use internal voltage regulation.  Having the oscillators highly dependent on the quality of voltage regulation coming into the unit is nuts IMO.  There is no single thing you can do to stabilize the oscillators more than voltage regulation - 3 terminal regulators are super cheap and really easy to incorporate into the design.

"I can confirm that the pitch antenna's responsiveness and accuracy if far superior to the Etherwave or Theremini. It was much easier to find notes by adding extended fingers in sequence. Seemed more linear too."

The Theremini pitch field linearity is crap, and the Etherwave can be bad too if it's not properly tuned.

"They state nowhere if the negative side is directly earth grounded. The description, for lab work and the round power cords says it should be."

I don't think the output on this supply is referenced to ground. Many lab power supplies have three output jacks; negative, ground, positive. You put a jumper from negative to ground or positive to ground and then whichever side is grounded is held at ground and the other output gives the voltage relative to ground. i.e. 16.7V positive relative to ground, or 16.7 volt negative relative to ground.
I think this unit "floats" with no reference to ground at all.
I'm not sure that matters. I think the amplifier provides the ground. Otherwise my Melodia would not be playable because it runs on a 6 volt battery.

I like that power supply, it will have value for you in other projects.

Unplugged just stick your ohm meter probe in the negative side and touch the lead to the ground terminal on the 3 prong plug.

If zero ohms it is directly earth grounded, high ohms it is not.

With any troubleshooting you need to begin with this solid and regulated power supply set at 15 volts, maybe drop down to 12 volts as a test.

Christopher