"Okay then, i will try to make the 40mHy coil as a single layer air core (0.15mm wire), or maybe start with one of the samller ones" - El Pepe
The 19mH I wound took maybe an hour to do, and even with the 3D printed ridges to guide the wire it was kind of a bear, with many starts and stops to remove accidental overlaps and such. 0.15mm wire is in AWG 35/36 territory, which is even finer than the AWG34 I wound my 19mH with. To me it seems that every two AWG steps up roughly doubles the winding difficulty (for single layer solenoids). Anyway, good luck!
I have succesfully (?) made the 40mHy coil. 11cm of diameter and 13,8 cm long, quite a task. i upshoot just in case (i hadnt used the coil calculator before) and the measurements indicate around 44.5mHy i reality, but i can reduce it.
I connected the coil where it should and after a few minutes of tweaking, it produced an expected behaviour and dynamic range of around 0-2kHz with antenna-only manipulation, splendid! Still, this behaviour was very instable and it seemed to depend on the orientation of the coil (almost like it had loose conections or the conection cables were interfering, i thought).
The issue is that after some more minutes of tinkering, it sadly stopped having that behaviour entirely
To be precise, the antenna lost all its sensitivity. The strange thing is that disconnecting the antenna to the coil, let me use the coil itself as an (super sensitive) antenna, as it is known, but connecting it removed even that possibility.
Below some videos to show the behaviour
(if it looks like there there is change in frequency but the tunning is off, its not that. I already checked on a lower frequency)
I thought about the coil connections i made, to be honest they look like trash but that shouldnt cause this. Apologies if this looks like a dummy's troubleshoot, i think i may be missing something obvious.
"To be precise, the antenna lost all its sensitivity. The strange thing is that disconnecting the antenna to the coil, let me use the coil itself as an (super sensitive) antenna, as it is known, but connecting it removed even that possibility." - El Pepe
That's a big honkerin' coil!
I notice in your second video that the antenna wire is very close to one of your smaller coils. The wire acts like an antenna too, so it's best to keep it away from stuff. Similarly, in your photo the coil wire is laying against the windings, which is also kinda bad.
The pitch side of an equalized Theremin has three resonances: 1. The fixed oscillator LC tank. 2. The variable oscillator LC tank. 3. The EQ inductor L and the antenna C.
The resonant frequencies of 2 & 3 need to be very close to each other and precisely tuned in order for it to work. So the variable LC tank needs an adjustable L or C to accomplish this tuning. An the fixed LC needs to be tunable too so you can place the null point where you want it.
You can use clear nail polish (like coil dope) to fix the windings. Run a few lines down the length, you don't have to coat the whole thing.
I notice in your second video that the antenna wire is very close to one of your smaller coils. The wire acts like an antenna too, so it's best to keep it away from stuff. Similarly, in your photo the coil wire is laying against the windings, which is also kinda bad.
That makes sense, i feel that ive tried this but im not sure, i would be relieved if this was the problem.
The pitch side of an equalized Theremin has three resonances:1. The fixed oscillator LC tank.2. The variable oscillator LC tank.3. The EQ inductor L and the antenna C.The resonant frequencies of 2 & 3 need to be very close to each other and precisely tuned in order for it to work. So the variable LC tank needs an adjustable L or C to accomplish this tuning. An the fixed LC needs to be tunable too so you can place the null point where you want it.You can use clear nail polish (like coil dope) to fix the windings. Run a few lines down the length, you don't have to coat the whole thing.
Yes, im still waiting my variable inductors to arrive, they would make everything much easier on that aspect but maybe ill try by moving windings.
Im gonna keep trying with this coil and make the smaller inductors to see if they solve the problems in the volume circuit too.
