Looking for an analogue CV output only theremin circuit design

Posted: 1/27/2017 6:57:35 PM

From: Moncton, New Brunswick, Canada

Joined: 4/24/2015

Hi folks,

I'm looking for a circuit design for a CV output only theremin. 

Something simple will do... no need for audio output, or any fancy adjustments... just CV output only.

Having both pitch and volume antennas would be great... as would the ability to tune each of them... however... worse case scenario, I could work with just a single pitch antenna outputing a single CV.

I'm hoping to etch a bunch of these boards... build 13 of them to be functional.. and then have another 13 boards, that are etched, but don't get assembled at all as I will be integrating them into some 2-D visual art projects that hang on the wall... that's why I'm looking for something analogue... would like it to be on a single board... 2-D as possible.

If anyone has dabbled in making CV output only theremins... I would love to hear about it!

Thanks so much!






Posted: 1/27/2017 7:26:04 PM

From: Colmar, France

Joined: 12/31/2007

I fear that the only reasonable concept for that is actually the open.theremin uno v3. I had breadboarded something very similar, a pitch and volume CV only theremin (with the idea to add midi later), a few years ago, but behind the analogue front end (oscillators), there was an ARM Cortex M0+ processor, though, so it wouldn't have met your requirements.

Posted: 1/27/2017 8:07:17 PM

From: Northern NJ, USA

Joined: 2/17/2012

People tend to have more analog than digital background, and so gravitate to analog solutions.  There are devils in the details of both analog and digital (DSP), but if you're looking for true simplicity, analog generally loses to digital.  This has been the case for decades now.


Posted: 1/27/2017 8:27:09 PM

From: Moncton, New Brunswick, Canada

Joined: 4/24/2015

Simplicity is not the reason for looking for analogue... it's more conceptual...
however, if there is a design that can be built on a single board... I'd be into it even if it has a digital chip or processor.


I'm looking for a schematic design because I'm working on custom PCB etching with intricate decorative designs... just looking for something I can etch onto a single board.  If it has a digital chip or processor, that's fine if it's the only solution.



Posted: 1/27/2017 8:47:37 PM

From: Northern NJ, USA

Joined: 2/17/2012

How accurate does the CV have to be?  If this isn't a musical pitch case, you might get by with something more akin to the volume side of a Theremin, where you're measuring phase offset of resonance.  I believe at least one Theremin uses this technique for both axes, it's similar to FredM's "upside down" approach.  Drive an LC with a fixed oscillator and look at the phase offset between drive and resonance, or just look at the amplitude (envelope) of what the LC is doing.  That's the simplest method I can think of for getting a voltage directly from LC resonance, and can be done either analog or digitally.

Posted: 1/27/2017 9:00:35 PM

From: Moncton, New Brunswick, Canada

Joined: 4/24/2015

It doesn't have to be super accurate.

The CV will only be triggering 13 different things... so it's not like I need multiple octaves or microtones.... The whole range will only be divided into 13.... and both the "pitch" and "volume" antenna circuit could be built identically...


I'm just looking to have electrons from the human body... go through the air... to the antenna... to send a control voltage...

My conceptual interest is in the human body being part of a capacitor to ground.
so I'm trying to avoid proximity sensors and photo cells and workarounds like that... the important thing for me is the human body to air to antenna part... that then sends a control voltage.

Posted: 1/27/2017 10:33:32 PM

From: Northern NJ, USA

Joined: 2/17/2012

Your project isn't clear to me.  "Triggering?"  Will you be dividing one CV into 13 ranges?  Or will there be 13 sensors that are thresholded?  

Posted: 2/2/2017 3:51:57 PM

From: Birmingham, England

Joined: 2/2/2017

I'd also love a simple theremin design made from basic components! Any one got one they can give us a look at?

Posted: 2/2/2017 10:45:10 PM

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014

."I'm just looking to have electrons from the human body... go through the air... to the antenna... to send a control voltage... "

I love your poetic expression for electronics, so many have lost touch with the natural, even the divine?

Avoided my medication today so I could type this. The other day got rid of the red haired RS clown and now back here with half a brain and memory. If you find no other way I have commercially made PCB's I give away. This Main board will control either pitch or volume. The boards are identical with minor parts changes and can give full analog theremin audio sweep, 24” control field. Either board can give a clean square wave at any regulator voltage. 5v, 9v, 12v. My board will also give you an ideal controlled 0 to 5vdc or 0 to 10vdc.

Do you have someone assisting you in building and principles?

I can send you a couple of boards but do not have the brain-power to troubleshoot anymore, so let me know. The boards are only partially stuffed in the photo. The Mouser parts list I can easily bring up to date, building only one board is about $35 in stuff.


Posted: 2/3/2017 12:07:35 AM

From: Moncton, New Brunswick, Canada

Joined: 4/24/2015

Sorry for the belated reply... we had a big ice-storm in New Brunswick... I was without power for 6 days (which means no running water either since I'm on a well).... and still have no phone or internet 10 days later... (tethering from my cell phone data right now).  They figure phone lines will be back up next Saturday... eep!

k. so.

Thierry, when you said that your breadboarded concept wouldn't meet my requirements... why is that?  Is that because of the ARM Cortex M0+ processor?  Because it wouldn't be fully analogue?  I would still be very much interested in that if you would be willing to share the schematic... It doesn't have to be fully analogue... I am in the end converting it to binary anyway.

Dewster, sorry if it wasn't clear... I'll try better... so, I made a prototype using a Moog Etherwave Plus... ran both the volume and the pitch CV into an arduino ADC where I wrote a program to convert the continuous CV into binary, using slip packets... then the binary information was sent into another program written in SuperCollider to trigger one of the 13 audio wav files (contact mic recordings I made of 13 radio towers)... the information was also routed into another program written in Processing to trigger 13 images... so when it was all set up, the theremin pitch and volume CV were each routed into a little black box containing the Arduino ADC... which was then connected to my laptop via USB... and the laptop was running the SuperCollider and Processing programs that used the binary data to trigger the 13 audio and image files... so when I played the theremin, instead of hearing the sound of the theremin, I was triggering (or playing) the recordings of the radio towers and the images of them... the programs contained fades as well so I could fade between audio recordings and images... there is apparently video documentation of this performance that I did in Toronto last fall... but I don't have it yet...

The next step, is to build 13 of these, so they can be played by dancers... but I can't afford 13 Moog Etherwaves... and I only need the CV output... not the audio, and no need for any of the waveform or brightness adjustments. 

I also ran this set up with a PAiA Theremax 9505... I thought of trying to modify that circuit so it would only have the CV outs and not the other options... but it is a bit over my head to know which components to eliminate from the schematic.

I did build a version of this last fall, using capacitance sensors (that had to be touched) to build a large scale version of this for an arts festival... it worked great... and in theory, I could just use that one for my performance this spring... but I'd really like to make it work with theremins instead of capacitance sensors (I used copper dish scrubby pads for the capacitance sensors)... Vice Magazine did a little video spot on that installation... you can see it here... I want to rebuild this same installation with theremins instead of capacitance sensors:


Does that give a more clear idea of what I'm trying to do?


Christopher, I would definitely be interested in checking out those boards you mentioned! Do you want to send me a direct message and let me know the best way to go about this?  Thanks!





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