Lenzless resonant transformer

[verpies]

I watched the video and did not notice any error, can you explain what was wrong ?

Just that a light bulb is a false power indicator when it is not the load itself.
In your test, the bulb on the input side does not constitute a load - it is only in series with the load (the primary winding in this case), thus you cannot draw any conclusions about the input power based on the brightness of this bulb due to MPTT.

However, you can do so with the other bulb on the output side, because there the bulb is the load and the power measuring device, in one.

The video also shows that the input bulb is off and the output bulb is on, but the circuit still draws significant power from the sig.gen.

Any idea what would happen in the primary when the load is disconnected ? Would primary go out of resonance and light there would lit up again ?

I assume that by the word "load" you mean the bulb connected to the secondary winding.  This is not obvious because the primary LC Tank can also be considered a load to the sig.gen and the input bulb.  You must be more precise when using the word "load'.

If the secondary winding was interrupted, then it would act as if it was not there.  The impedance of the output bulb would cease to be reflected by mutual inductance to the primary winding, which would cause its apparent inductance (and inductive reactance) to increase.  This would detune the primary LC Tank from the resonance frequency and the input bulb would light up. 
You can almost see it at 3:57 when the primary winding is still over the ferrite rod but already away from the secondary.

[Jack Noskills]

Did some testing using shorter secondaries and result was not good. I got the same behaviour as before but not much light in the output. About 90 turns primary and 22 turn secondaries, so all I got was a stepdown action.


This means no resonant rise in the output and not scalable to high power as such. Something is still missing.


I see if I get lucky with my tiny E-I ferrite, I will try to make isolated resonant LC in the middle and use the other two coils for load, also resonance there.

[Jack Noskills]

I finished playing with the ferrite E-I. I used 200 turns in each coil, also the primary had about 200 turns. Best results I got when I placed capacitor in the middle of the ferrite so it formed an isolated tank circuit. Other two secondaries were connected together via another capacitor, same setup as before.


I could vary the inductance of the middle coil, 50, 150 or 200 turns. I also varied capacitors and tuned whole system as a whole. There was always a sweet spot and when the drive frequency was the same then shorting the output had no effect on source. Also putting a load had no effect on source. I was unable to tune the primary but still it worked well.


Side lobes of the ferrite core were 3mm x 8mm and about 50 turns fitted in it. Middle was 6mm x 8mm. My source had 5 watt halogen and no light there while output was 10 watt halogen and almost full brightness.


I tried the same using bigger nanoperm core but it was not as good as the tiny ferrite. So E-I is much more efficient than toroid since there are three coils working together instead of two.


Now I wish I had a scope so I could see the voltage waveform in the isolated tank compared to voltage waveform of the output when the whole system is tuned.

[wistiti]

Hi jack!
How do you connect the load on the primary serial or paralele with the source?
I gave it a try with a tv yoke this weekend but did not acheive great result

[Jack Noskills]

There is a picture in the PDF how to tune output part and when tuned how to connect the load.


Were you able to find resonance at both sides ? It does not work well without resonance. Also if you find resonance but there is not enough turns in your primary it also does not work well.


A good starting point is to 1:1 ratio with all coils and enough turns in your primary so it blocks current flow without capacitor. Then you can begin to explore it, you will have a working baseline setup to compare against and see what is good and what is bad. Start from low voltage so it is safe to handle. Gain knowledge of it and then gradually increase voltage.