Induction Balance Stuff - Single/Multi Frequency Response, GB, Disc, Measurements, Ideas, Fun, etc.

[Aziz]

Hi all,

I have changed slightly the LC-tank circuit. And put a DPDT power toggle switch simulation via jumper.
There is only one big tune capacitor Ct (instead of two bigger). FKP1 foil capacitor with low losses if possible.
The small capacitors Cs2 and Cs3 are now doing the voltage division (capacitive voltage divider).
Keep Cs2 as low as much. Change Cs3 if required.
Cs1 is a compromise between power and high-Q. Make Cs1 bigger and you get more power to the TX coil but the Q will go down.



Below is a zipped LTSpice simulation file for your convenience. It simulates a time-domain circuit behaviour for -0.5%, 0% and +0.5% change of TX-coil inductance approx. 200 Hz above the resonant frequency. If you make an AC analysis, Q can be calculated in the graphs. Q = I(Ltx) / I(Cs1), this is now the correct calculation.

Aziz

[ivconic]

Nerds all over the place!
God help us!

[Aziz]

Alternatively, we can operate the transmitter at two different frequencies close to the resonant frequency (fr) of the LC-tank.
Left-channel: fr-100 Hz
Right-channel: fr+100 Hz
We get a nice 200 Hz modulation of the TX-ref signal however.

[Aziz]

Hi all,

this is the high-power High-Q transmitter I am talking about with additional capacitor (C1) and choke (L1). So there is enough power to operate it even in IB-coil configuration.
Note, that the input is only 1 Vrms (+/- 1.414 V peak to peak, typical line-out level). We can increase the input coupling capacitor Cs1 to get more power (470 pF in this configuration). This won't degrade our TX-Q much.

By carefully setting C1 and L1, we can increase the TX power further. It's own resonance frequency should be lower than the LC-tanks resonant frequency. C1 and L1 is beeing operated at low-Q only and it steps-up the line-input voltage.


The configuration is very sensitive to TX-coil inductance changes and resistive losses. Let's look, where we want to operate it:
- close low side to the resonant frequency
- at exact resonant frequency
- close high side to the resonant frequency.


Aziz

[Aziz]

Google AI gave me further interesting software concepts for the external free running LC-oscillator too.
Implementing a combined SPLL (Software PLL) with Lockin-Amplifier. The complex output can still be used for the Hilbert-Transform for instantaneous Evelope(t) and d Phi(t)/dt analysis.
The SPLL tracks the oscillator frequency and locks into it. Nice.
Aziz

[Aziz]

I have another version with more TX power. The feed-in is made via another capacitor and choke. This will decouple the source impedance further and will increase the TX coil current due to inherent source voltage step-up of the input. But this is not efficient as a lot of energy is not going to the LC-network. I will test the basic variant first.

[Aziz]

Hi all,

this is the basic tuned High-Q transmitter I am going to test soon. Q is almost 300 (theoretical without the losses of the capacitors).
Note, that the coupling capacitors Cs1 and Cs2 are kept very low to maximize the Q. The series split of the resonant capacitor (Ct1, Ct2) is required to decouple the LC-network from the input impedance of the sound card. So the LC-network may not be loaded much by source and measurement impedances.
The phase change around the resonant frequency is very very steep. Bandwidth (BW) is very low (<200 Hz). So it minimizes the incuded EMI noise outside of the BW. This could increase the detection sensitivity on mono coils. Also the ground effects.


Aziz

[Aziz]

Hi all,

I had interesting chats with the Google AI recently. The fkn machine taught me some basic interesting concepts.
Then I found an interesting way for the mono coil VLF. There is a very simple way of increasing the response sensitivity.
High-Q, narrow bandwidth (<200 Hz) driven parallel LC network. For Q > 100, 200, up to max possible...
I am peer-reviewing this concept with spice simulations now.

I haven't given up the mono coil concept yet.
Aziz

[Aziz]

Hi guys,

yep, Windows is a very special case. It's a pure bloatware.
I had three active add-ons on Firefox browser recently: Adguard, Savefrom.Net Helper, Youtube Adblock
One of them did occupy the harddisk 100% so you couldn't work with the PC anymore. It was active within 2-5 minutes, if the PC was inactive (no user interaction).
WTF, one of them is spying me and my files. I have deactivated all add-ons now.

Windows 10, 11 is doing similar work in the background. No thanks.
Aziz

[ivconic]

Why using Win7? I missed something?
Win10 is very good. Set it up as you prefer and at the end use WUB to prevent any unwanted Win11 update.
I have Python 3.10.11 on it with all the requirements needed. Works like a charm.
Ain't no faster way from the idea to final code.

[moodz]

Hi all,

it's a shame. I couldn't install python on Windows 7. (It must be a bloody amateur coding work.)
I have asked Google AI and followed the instructions. It succeded then. Version 3.8.10. This is the latest version on Windows 7 (64 bit).
I am expected 1001 more troubles using python. Yep. It's a bloody amateur coding work.

You are absolutely right Aziz.... Windows is written by amateur coders, .Windows updates and associated restarts waste roughly 47,500 man-years of productivity annually globally.

[Aziz]

Hi all,

it's a shame. I couldn't install python on Windows 7. (It must be a bloody amateur coding work.)
I have asked Google AI and followed the instructions. It succeded then. Version 3.8.10. This is the latest version on Windows 7 (64 bit).
I am expected 1001 more troubles using python. Yep. It's a bloody amateur coding work.

[Aziz]

Hi Paul,

PS the secret to using CC is not to tell it what to do ..... tell it the problem you are trying to solve.

Yes, I made the CC a very complex query. But it still solved well. I have to learn to make right queries to the AI yet. I'm a bloody beginner. I'll try another queries soon.

Aziz to even be in the ballpark ... you need a few orders more of sensitivity.
The method I use results in a frequency sensitivity of 16 uHz or 0.000016 hz at the phase detector. ( 100 nV of signal to noise )
If the target is 2.5 diameters away from the coil .. thats a very small change in the far field to get back into the detector.

100nV is around -200 dB! That's a long way to get there.
I don't know yet, whether I can get into the same region. But the "damped ringing PI" is a good candidate for. The complex demodulators reduce a lot of noise and are translating the signals into the low frequency time-domain signals without additional noise. And I don't need any front-end amplifiers.

Cheers,
Aziz

[moodz]

This is nothing special ... a basic crystal oscillator on a CPU board such as I am using will have 20 ppm spec over a wide temperature range.
Basic crystal oscillators can hold a stability of ±20ppm over a wide temperature range (e.g., -40 to +85°C). So 16 uHz is not a big thing.
The CPU is dividing the 25 Mhz clock down to 5 - 100 khz .. so spec is even tighter.
The main problem for the Franklin oscillator is that it might have stability as far as LC oscillators go .. but is far away from the stability of even $1 crystal oscillators.

[moodz]

Hi all,

I have now 2 Google AI and 1 CC solutions for the Complex FIR-Bandpass. All behave same.
I can detect frequency changes of 0.001 Hz of my Franklin LC-Oscillator now. This is insane. The Complex FIR-Bandpass is the most powerful tool ever.
I will get rid of the standard Hilbert-Transform. The bandpass works only for the Q-channel.

Aziz to even be in the ballpark ... you need a few orders more of sensitivity.
The method I use results in a frequency sensitivity of 16 uHz or 0.000016 hz at the phase detector. ( 100 nV of signal to noise )
If the target is 2.5 diameters away from the coil .. thats a very small change in the far field to get back into the detector.

PS the secret to using CC is not to tell it what to do ..... tell it the problem you are trying to solve.