basic experiments

JPascal, do you know of any coil software that helps you design things like RF chokes?  You know, multiple multi-layer windings "donuts" on the same former (like in the Etherwave)?  There's plenty out there for single layer solenoids, and even two single layers.  And there's a couple for multi-layer, but only for a single donut.

Do you plan to share the schematics?  I would love to build one.  One reason I asked about a PCB is because I can help with that, I am an electrical engineer and would be willing to help move this project forward any way I can.

Yes I do. And I am very interested in a trusting collaboration with an electronics engineer with experience in RF and in music electronics. But let me take some time to explain the innovations in an overview article. My experiences with sharing “out of the box” results vary widely.

If you do something that's a little bit different from the general consensus, many experts feel like they have to pounce on you, find a small mistake (since you're not equally professional about everything), and put you in your place. The other extreme is the complete refusal to even acknowledge what is creatively new. Examples of this include Dominik Bednarz's revolutionary volume solution, which I was able to rethink (during a rehab stay without the usual stress) based on his published demonstration and develop into my own solution. There have also been a number of things like this in this thread over the years. That's also because we obviously didn't explain it clearly enough.

My difficulties with English also easily lead to my results being downgraded. But that is a broad field. This forum is increasingly becoming a wasteland and will soon run out of life, as we know from the moderator.

JPascal, do you know of any coil software that helps you design things like RF chokes?  You know, multiple multi-layer windings "donuts" on the same former (like in the Etherwave)?  There's plenty out there for single layer solenoids, and even two single layers.  And there's a couple for multi-layer, but only for a single donut.

For a single donut coil you can trust this tool:
https://www.electronicdeveloper.de/InduktivitaetLuftMehrl.aspx

After this you have to define a couplingfactor between two of them (experimentally i would recommand). And the third coil couples similar. The Q is also then simple to estimate. That would be my way.

Thanks JPascal!  

There's also this with a handy AWG list and more practical solving targets:

https://coil32.net/online-calculators/multilayer-coil-calculator.html

Links up at the top and off to the side to various calculators.

I can't believe there isn't software, or at least some form of ancient table or other manual guidance to make these things which were pretty common only a few decades ago.  I imagine a ferrite core would really complicate things, with various formulations, distances, etc. but an air core RF choke seems very analytically solvable.

For coupling one might be able to use two single layer windings in INCA.  Even small distances seem to hugely reduce coupling.

Coupling is nice because it boosts the inductance value, and can therefore be used to reduce the DCR and increase the Q.  But beyond that I'm not sure how important coupling between the donuts actually is.  We obviously want the "cold" drive end somewhat physically separated from the "hot" antenna end in order to minimize self C.  I've read that the cross section of the windings should ideally be square, which makes sense in terms of packing the turns together for coupling within the donut, but IIRC it's a broad maxima.

Taking the square donut winding cross section as something of a given, I imagine the optimal number of donuts would be rather high?  Not that it matters, scramble winding on a 3D form (in spindle slots) would be much easier than making a single layer solenoid, particularly when the AWG gets above 30 or so.

I guess I could select an AWG that makes sense for a given DCR / Q / mH, then experiment with these programs.  Physical tests could perhaps scavenge the wire back to do many such tests without creating a lot of waste.

There's the possibility too of counter-winding half of the turns, which would give negative coupling, but would be something of a "humbucker" for AC magnetic fields.

Do you plan to share the schematics?  I would love to build one.  One reason I asked about a PCB is because I can help with that, I am an electrical engineer and would be willing to help move this project forward any way I can.Yes I do. And I am very interested in a trusting collaboration with an electronics engineer with experience in RF and in music electronics. But let me take some time to explain the innovations in an overview article. My experiences with sharing “out of the box” results vary widely. If you do something that's a little bit different from the general consensus, many experts feel like they have to pounce on you, find a small mistake (since you're not equally professional about everything), and put you in your place. The other extreme is the complete refusal to even acknowledge what is creatively new. Examples of this include Dominik Bednarz's revolutionary volume solution, which I was able to rethink (during a rehab stay without the usual stress) based on his published demonstration and develop into my own solution. There have also been a number of things like this in this thread over the years. That's also because we obviously didn't explain it clearly enough. My difficulties with English also easily lead to my results being downgraded. But that is a broad field. This forum is increasingly becoming a wasteland and will soon run out of life, as we know from the moderator.

Well I am interested in continuing the conversation in a productive manner, whatever form that takes.  I am particularly interested in how the timbre was achieved.

Thank you Triode. Would I always be retired, it were no problem to start just now. 

To the multilayer coils. I did a simple test configuration with two coils. Here the results with the increasing inductance. The shortest distance is here 7 mm between the middle of the thickness when the coils are in touch.

 

Thank you for going to all that trouble JPascal!  Your results are very similar to those of INCA, where the two coils are single layer.  Not a huge total inductance difference with k.

Yes I do. And I am very interested in a trusting collaboration with an electronics engineer with experience in RF and in music electronics. But let me take some time to explain the innovations in an overview article. My experiences with sharing “out of the box” results vary widely. If you do something that's a little bit different from the general consensus, many experts feel like they have to pounce on you, find a small mistake (since you're not equally professional about everything), and put you in your place. The other extreme is the complete refusal to even acknowledge what is creatively new. Examples of this include Dominik Bednarz's revolutionary volume solution, which I was able to rethink (during a rehab stay without the usual stress) based on his published demonstration and develop into my own solution. There have also been a number of things like this in this thread over the years. That's also because we obviously didn't explain it clearly enough. My difficulties with English also easily lead to my results being downgraded. But that is a broad field. This forum is increasingly becoming a wasteland and will soon run out of life, as we know from the moderator.

Thanks Jean for pointing to the velocity volume solution. Appreciated! Another feature i build in optionally is white noise. New innovations by either Dewster or you come to mind: dirty-freq-filtering directly at the antenna and frequency dependent harmonics.

Now to one of the last unanswered questions for me and others in the community regarding linearity and timbre change in the very low beat frequency range of an analog theremin.

There are some premises, I have detailed the math behind them in this thread “basic experiments” with some formulas and a row of experiments:
1) Pitch is almost linearly proportional to hand capacitance.
2) The hand capacitance is a function proportional to the reciprocal of distance x ln(distance/rod radius)
3) The pitch knob is used to set the beat zero position. An offset of the fixed oscillator to the variable oscillator is used for this purpose.
4) The "pitch linearity" is only given in those sections of the hand distance in which its logarithm over the distance is a nearly straight line. Than all octaves have the same distance.

Point 4 is not possible both in the very near field and far away of the antenna. 

But can the coupling (inductive or capacitive) between the to oscillators influence this behavior, in the best case create linearity in the zero beat zone? I mean yes, if a proper coupling occours. Coupling has here three effects: 
A) The beat frequency is than more or less compressed with respect to the distance change. This can lead to better linearity in the far away zone.
B) If the coupling is too strong, both oscillators snap into the same frequency, beat remains zero in a certain distance range.
C) The timbre (overtone behavior) changes strong near zero.

"But can the coupling (inductive or capacitive) between the to oscillators influence this behavior, in the best case create linearity in the zero beat zone? I mean yes, if a proper coupling occours."  - JPascal

Years ago I read somewhere (FredM maybe?) that the tVox uses oscillator coupling to improve the linearity.  I wonder if ILYA could incorporate coupling into his simulator?  I have no idea how the math would work out though, it would likely require a certain amount of experimentation.

I believe the EPro, Hobbs, and the recently updated (and discontinued) Etherwave have a coupling adjustment.