Burns B3 Guts

Posted: 3/27/2020 1:43:45 AM

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014

Pedro visit my TW webpage

The Finest Theremin Ever Conceived


Posted: 3/27/2020 7:33:43 PM

Joined: 3/26/2020

Pedro visit my TW webpageThe Finest Theremin Ever ConceivedChristopher

Impressive Mr. Christopher, really clean work, a true purist. But a few steps up from my knowledge.

Hope some day I can purchase some boards from yours. In the moment it's impossible to me.

Back to the point of the topic, here is my schematics to the B3 Burns Theremin:

The one I have in my bench is almost the same of the initial images of this topic, but the volume potentiometer is different in shape. And has a 78L regulator IC for each board.

What I'm curious about is the way he puts the signal out.. very interesting.

Recently I figured that many people complains about volume drop, or "tone suck", hope the schematic helps.

And thanks to the developer of this simple but functional device, my goal is to enlarge knowledge, as I can, to the comunity.

Posted: 3/28/2020 8:10:59 PM

From: Guadalajara, Jalisco, Mexico.

Joined: 7/5/2019

Thank you very much Pedro, confirm that my schematic was very close, I hope to try it soon and share the result.

Posted: 3/28/2020 8:35:56 PM

Joined: 3/26/2020

Thank you very much Pedro, confirm that my schematic was very close, I hope to try it soon and share the result.

Mr Goño, you was a hero! Tracing up the schem only by seen pictures of it, my respects to you.

Hope it to be helpful!

Now I'm working on the tone and output section.

Posted: 10/23/2021 5:31:30 AM

Joined: 10/22/2021

Pedro visita mi página web de TW El mejor Theremin jamás concebido ChristopherImpresionante Sr. Christopher, trabajo realmente limpio, un verdadero purista. Pero algunos pasos por encima de mi conocimiento. En el momento me es imposible.Volviendo al punto del tema, aquí están mis esquemas del B3 Burns Theremin: El que tengo en mi banco es casi el mismo de las imágenes iniciales de este tema, pero el potenciómetro de volumen tiene una forma diferente. Y tiene un IC regulador de 78L para cada placa. Lo que me da curiosidad es la forma en que emite la señal ... muy interesante.Recientemente me di cuenta de que muchas personas se quejan de la caída de volumen, o "succión de tono ", espero que el esquema ayude.Y gracias al desarrollador de este dispositivo simple pero funcional,

Hello Pedromariz88, the truth is if I made the circuit that you made in the diagram, but I only have a problem with the volume of the theremin, the pitch already works for me, any advice that you can recommend or will it be that I have to apply the schmitt trigger

Posted: 10/23/2021 12:28:10 PM

Joined: 3/26/2020

 Hello Theshieldevil,

I'm glad that the schematics inspires you to build.

Well, the low output I solve by adding a simple discrete transistor as an amplifier, after the output.

Any single transistor amplifier topology will work. I just don't recomend very high gain ones.

In other words, put a boost circuit at the output.

Posted: 2/11/2022 1:31:24 AM

Joined: 2/6/2022

Hi All,

Don't know if anyone is still watching this thread.

I'm new to the theremin and to this forum.

I recently bought a Burns B3 theremin, and find that the Volume field is a bit too wide for my liking, making it difficult to articulate notes.

Is there a relatively simple way to shrink the volume field to a smaller width/height?

I see in the photos here that there is a pot on the Volume board, but don't know if tweaking that would accomplish the desired result.

If not, I am comfortable enough soldering that I could augment the circuit by adding or replacing resistors.

I'm just not knowledgeable enough to know what to modify.

Thanks for any help with this.


Posted: 2/11/2022 1:54:31 PM

Joined: 3/26/2020

Hi smwells5,

I sugest you to make a pencil mark at the actual position of the trimmer that you will turn. And then make a litle turn and hear the difference. 

Remember the B3 is a too simple circuit, it works as it is and any change can unbalance the original circuit stability.

In the other hand, as it is too simple, it is a invitation for playing whit its controls, as far as you can return every trimmer to the pencil mark.

Hope it helped.

Posted: 2/15/2022 1:51:41 AM

Joined: 2/6/2022

Thanks Pedromariz88 for the tips.

I tweaked the trim pot on the Volume board and was able to dial in my optimal field.

I find it to be a very sensitive adjustment. The entire turn arc of adjustment is only about 5 degrees. Anything outside of that results in no sound.

Posted: 3/30/2022 8:44:42 PM

From: Guadalajara, Jalisco, Mexico.

Joined: 7/5/2019


Playing with the volume circuit (which works very well despite its simplicity) I have tried to replace the oscillator, I measured the oscillation of the antenna and it fluctuates a lot with the noise of 60Hz, I would like to keep it without inductors (although adding a small choke instead of the resistance, it increases the oscillation of the antenna very much, in addition to looking more like a sinusoidal wave), with the second oscillator, the oscillation of the antenna looks more stable and works the same, without modifying the rest of the circuit, powered by 12 volts and measured with my homemade 100x probe.


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