hmm I thought I wrote the data down of the first 2 layers. strange.

anyway I now have 9 layers total
of which the first 2 are 1.5mm
and the next 7 are 1. 4mm diameter wire.

without the iron core, the inductance is
1.9757mH  Q=15.12
with core fully inserted:
7.085mH  Q=15.8
measured at 100kc/s

I will now test it again. My guess is the resonant frequency is much too low now.
I can then remove the core until I got the right frequency (48kc)

but I will probably remove some of the windings again, to get the core more in, as it will contain the magnetic field a bit more which might be good with all that cold current that will start flowing

I tested, and the push pull drive coil is still resonant around  63kc/s  which is bad. I need to reduce secondary windings.
I searched for a higher harmonic, and got it at 183.34 kc/s which is still very high. I blame the resonant drive coil for this.
With 10V and 0.3A from the PSU I only got 452. 76 V pp between the tuning coil and the HV coil capacitor plate (current and output coil grounded). scr758

This time I also grounded the primary PSU, but that should not have mattered, as it can float.

I then measured at the push pull secondary connection to the tuning coil (src760), and got even higher voltages of 618.15V pp
so... those 2 coils are dual resonant, while the main resonance should be with the coil capacitor.

This also means the tuning coil is in 1/2 wave mode, which means, when I get it into quarter wave mode, the frequency should drop drastically. Maybe half of what it now is, so 90 kc/s which is still high. but might be workable.

Lets rebuild that secondary of the push pull coil. to get its resonant frequency much higher, so I can drive it under its resonant freqeuncy. it will reatain more drive power, for the series resonance.  higher impedance into a low impedance load.

 at series resonance the electrical impedance is low and will demand high current,

 at the parallel resonance, the electrical impedance is high and it will demand high voltage.

hmm. so my push pull driver coil needs to be connected in  reverse?

not a 600v ac but... high current
hmm. thick wire few turns low impedance on the secondary.

I decontructed the push pull driver coil as it was all wrong.

Instead of 4, I used 2 stacked toroid cores for the new one.

I wound the primary with 17 windings of 1.5mm diameter wire, which gave 6.9mH (@ 100kc) with Q of 2.

The secondary will have thicker wire, with fewer windings for max current. but that will be done tomorrow.
enough done for today. its late

strange I hooked the coil up, saw the square wave at 50kcps but no current at 16.6Vdc supply ? is 6.9mH already to much?
yawn. tomorrow...

ah claculator says 2167.69893  ohm :huh:
ok... that explains it

XL = 2πfL
https://www.calculatorhut.com/physics/reactance.html

ok thus, rewind on just one toroid. fewer turns

I decided to wind a secondary on the toroid and see what it did. I gave it 3 turns.
series resonant frequency appears at 135 kc/s which is still high. but, this is without the parallel resonant coil (as it is now fully grounded).

voltage is very low, due to the push pull coil still being "bad"
I compared the voltage on each end of the HV coil, and it appears to be higher at the loose ends, so that's good.
I used 16.6V at 0.01 A to drive it, so the coil definitely needs less windings :)
back to winding.
I'll get there

green was current between tuning coil and coil cap. orange is the voltage at the same place. yellow the push pull primary
scr762 was the voltage at the loose end (orange)

lol I see I placed a 3.3uF cap where a 4700 uF cap should have been on the push pull section...
oopsy

not bad. but still...

oops. NO WRONG. that cap was good. OH well now I replaced it.... doesn t matter more capacity

OK, made a new push pull driver coil with 5 windings on a single iron core toroid, and the primary 1 winging (4 wires bundled).

I must be doing something wrong Or I fail to understand it.

Maybe the ground loop connection is to long?
maybe the push pull driver doesnt work correctly?

I should have gotten large currents... but dont.

need to check and recalculate.

ok lets forget about the push pull driver coil. that idea is nuts.

I will give my tuning coil a primary which will directly connect to the push pull circuit

and I will test my push pull circuit with a resistor. see if can get it hot with current

I have been working on getting the series resonance to. work.

the capacitor is the 3 coils.

I now have 2 coils tight together to. ground.

but one of them is the parallel resonant coil, which will produce the cold current.

and the cold current comes from the changing voltage.

So that voltage change is low, but the current it sets moving is high. So that would make sense it also drives the series resonance.

as the cold current is moving the coil capacitor field, thus should also drive the series resonance!

so it might need to working from both ends.

658 uH at 135kc/s = is still 558 ohms (Xl)
so with 16,6 volt/558= 30mA hmm

and that is the primary of the push pull

 I will reduce it to 1 winding

a single winding on the push pull primary measures 53uH at 135kc gives 45 ohms
16.6v/45=0.37 A which is still way to low.

So good to drop this iron core, and make a (single) winding around the tuning coil, measure that, and raise the voltage if needed to get the amps

A single winding around the tuning coil measures around 2uH at 125kc this gives 1,7 ohm
16.6/1.7=9.8 Amps.
ok that is better.

I will give it 3 turns, so I can increase the voltage to higher levels

3.75 uH for four turns at 135kc=   3.18086 ohms reactive
16.6V/ 3.18= 5.22 A

This is 4 turns of the thick induction cooker wire, which I also used for the high current coil.
Lets try and see

yes this works. 
psu 8V 3 A DC (24W)

frequency shifted higher (due to the primary windings close coupled) to 185 kc/s
voltage now at 1.6 kV pp
Still needs to adjust but going in the right direction.

yellow is the primary voltage which looks it can be improved (scrubber circuit?)

I could give the tuning coil even more windings, or... I could place more isolation between the primary and secondary coil, to give it a slightly looser coupling, and give the primary one more turn to get a bit less amps.

the mosfets now also need active cooling. I have 12V fans, which can be hooked up in series, and then to the 16.6V supply

I reverse connected the tuning coil, so the thicker 1.5mm diameter wire around the core is the resonant end connected to the coil cap. And the primary sits on the grounded side.
Frequency somehow moved up higher to 188 kc/s
but current draw from the PSU went down. I increased it to 15.2 V which demanded 3.55A DC (54W)
orange now shows the end of the HV coil cap (connected the same as before) and shows 3kV pp
square wave (yellow) from the primary also looks much better now.
I like where this is going.

Maybe...
Maybe its time to start including the parallel coil and tune it.
Although...
the frequency is still very high...
I could make a choke coil for this frequency, it will be good practice

Maybe it is time to rewind the tuning coil.
Use more toroid's, making it wider (I had made it smaller for the winding jig, but I wind it by hand).
I then can leave the primary on one side, leaving the other side as the resonant side open and uncoupled.
windings will be closer to the core.
core will still be removable. so It can be fine tuned.

now it has 5 cores, I might go to 7 or even 8. not more then that.
I also will need more windings to get the frequency down.
also less capacity to get the voltage up.

a zvs with a flyback,
uses a resonant primary with small coil and large caps to get high voltage in the secondary.

I have a flyback made from coper tape or something like that.

So... what if I use a large capacitor over my primary, and drive it into resonance with my push pull?

hmm yes. that will create the huge amps that I need to drive the coil into high voltages.

I still have two of these flyback transformers,
one is a bit damaged, but still should work fine.
I wonder what frequency it works at.

and If I can make the primary resonant, to get high currents flowing in that core

I.m just going to use my flyback coil that came with the zvs driver.
it ran at 68kc/s if I remember correctly.
it has 2x 4 windings, with 0.66uF in parallel.

I want to use my push pull, with 4 windings and to get the same frequency I would need... 0.66uF?

oh no... that coil has a rectifier diode built in... so it will not give ac

I want high voltage low current,
from a low voltage sourcd so I need high currents.

I decided I will use 2 12v lead acid batteries im series to get 24V with high current.

That should be a good power source.
also I can tap the series connection for the push pull half voltage.

I wonder if these high voltage laser flyback transformers also have diodes built in
if not I could use one of those

ah wait! I have car ignition coils
those are AC
lets see of I can Make  those work

hmm no, the ignition coil is a pulse transformer, not for continuous ac.
maybe it still can work but probably not.

So... My primary will be series resonant, with low inductance (few windings) and a large series capacitor.
This will generate high currents in the core from a low voltage power supply (26V)

The secondary is driven by the magnetic flux of the core.
The secondary has  a large turns ratio. low capacity.
In series with the secondary is the high voltage coil which also has inductance, and this coil has capacity to the ground of 175pF so it will also be resonant in total.

The impedance of the primary should be matched to the impedance of the secondary, for Ideal power transfer.

Thus... both are series resonant, but one side has large current low voltage,
while the other side has large voltage low current. both are resonant.

now how to design this?

the primary can be bifilar wound, to get larger capacity and current in the coil.
the secondary must not be bifilar. since it produces high voltage, it is best to isolate the windings.

I'm already windings the coils.
lets calculate what we need based on what we have.

assume f=85kc/s
C2 = 180pF
L secondary is asked. (I will calculate inclusing the series high voltage coil inductance, and later substract it)
https://www.calculatorhut.com/physics/lc-resonance.html
gives: 19.477mH
minus 1.337uH=18.14 mH that is the inductance of the secondary coil

at 85kc/s this is a Inductive reactance Xl= 9688.04343 Ohms
wire resistance will make it a bit higher.

Lets first measure what I now have on my secondary. I have around 15 layers made from 0.5mm diameter wire. Each 5th layer is taped over.