I reversed everything back to normal again.
HV coil end= where the hv coil is closest to the HC coil.
no load, load coil grounded on the open ended side of the hv coil again
Tuned into the max voltage, where current is in phase (hc coil still not perfect tuned)
no HC psu, only HV psu.
I could tune the drain voltage to this beautiful curve (orange)
slow rise in voltage.
fast decline.

only that ringing doesnt site well with me after the fast change in voltage.

I bound the voltage leads to gether, to get less ringing and it does seem to work a bit.

lost of amps again, for relative low voltages.
6.6App 1.8Vpp
14.9kc\s

only HC psu now.
0.01A 15.2V 0.15W
tuned to max current, which was already good tuned.

orange is the drain. ringing madly at turn off of the mosfet (from discharge choke magnetic field)
Then right before it counts voltage drops. 20/div is around 10V being switched.
slight ring at turn on of the mosfet.

It suprises me again and again to see the current max is not in phase with the mosfet switch.

also 3,8A from 0.15W it is a lot for almost nothing.
using the displacement current to produce magnetic current is definitely lucrative

same setting as last post, but now added the HV psu
2.13A 2.7V
HC psu has now 0.02A instead of 0.1, still 15.2V

current amplified to 8.1144App
at 14.9kc/s

higher voltages start discharging somewhere, 1.8kV pp was safe. need to check


I really need to get those voltages up, but I dont dare to push it
especially the HC coil DC voltage is low, but the choke needs some protection,
still dont understand

those ornage voltages look very good again. proper tuned

I taped the open connections of the HV coil. now I have a prefect sine again.
I also moved the loose coupling away from the metal of the hv probe so it can spark through the thin plastic tape.
this works good.
I gave a lot of power in the the HV coil
4.80A 7.2V 34.6W

So the actual voltage must have been somehwere around 20kV or higher.

The HV coil now is hissing, from the corona discharge. I should use more tape over it, but it will keep hissing, since there is so much air.
next time I should wind and tape it even better.

I removed the current probe

look at that orange voltage. 20V (drain, hc coil)
which is without the HC psu on.
20V just from the HV coil capacitive coupling.
While the HC coil is connected to neutral through the choke, and the HV psu capacitor.

If I would remove the positive voltage supply hc psu, and choke. then the coil would float
and produce much higher voltages, that then could be switched to neutral by the mosfet.

since the voltage of the HC would be Floating, it should not damage the mosfet?
but, the voltage change would not work, as the floating coil then only relativly changes its voltage, which has no effect on the displacement field. it is not a real voltage change by itself. just a reference point change.

current probe was turned off

caps are in, tuned it again, with 5x 1uF plus 4x 330nF all in parallel.
I put the blue probe on the output coil open end (other side earth grounded)
20V peak to peak.

current is 13A pp
voltage is 3.2kV (loose probed) so around 15kV?

frequency is 14.5 kc/s

orange (drain) is 43V at discharge, very nice.
still has a bump, after mosfet turn off, which not gives a ring?

mosfet turn on, gives a ring? weird. mosfet turn on is not perfect timed, but signals look awesome
HC psu 0.02A 11.5V 0.23W
HV psu 3.62A 5.3V 19.2W

nice is that the hv psu isnt loaded at all when the lamp is connected (at least that will I check now again)

I tried measuring the current in the open ended output coil,
but it is impossible, as the current probe pics up current in mid air (a sign of displacement current? or probe not properly grounded?)

lets load it, but first put some more lamps in parallel to get the resistance down

cold halogen lights also have a different resistance than hot ones.
maybe I should make something of resistance wire.

6x 20W 12V halogen lamps in parallel.
worthy of 10A

but as my dual psu shows it is slightly different.
put in parallel mode, where current can be added.

why are the channels unbalanced ?
needs calibration?
any way they glow nicely

cold resistance is 0.3 Ohm or lower.

12V/10A =1.2 Ohm hot

loaded 6x 20W!
not glowing

no voltage (orange) on load (6x20W 12V parallel)
2.6App on current coil is low. should be more like 20A
0.01A 13.9V on HC psu, square wave looked good, nice fast discharge

voltage is 3.1kv pp on the edge of corona discharge (hissing and scope noise)

I played with tuning the square wave to the max volt point.
but no luck so far

I romeved that cursed choke,
and instead connected the HC directly to the hv AC transformer (neutral removed).

so the AC transformer is driven half wave, one side to the HV coil, other to the HC coil.

HC coil has mosfet that can switch the HC coil to neutral.
Since the mosfet has a body diode, the negative cycle is grounded to neutral.
only the positive cycle builds up a positive voltage.
At the positive maximum this is then discharged.

This is very interesting. but no magnetic current is developed, must reverse connect the HC coil to see If I can create currents.

Blue is the HC coil (hard probed)
yellow is the HV coil (loose probed), you see the voltage shoot down to more negative.

orange is the mosfet signal.

Very interesting to see all of this.
And without any large ringing from that cursed choke.

I reverse connected the HC coil.
Still no amps.
voltage still oppositive, and the same effects.
I might need to reverse connect the mosfet (drain source).
because that reverses the body diode,
then I could discharge the negative cycle.

but as long as the voltages are out of phase, It wont really matter.

I should switch the non r3sonant sode of the hc coil,
which is where the ac coil is conmected.

the mosfet bosy diode still connects the ac coil to t neutral.at the negatice side.


then the oositive side the voltage grows positive and it then again swit hed totnneytral.

hc coil stillnis allowed to become resonant with the cap.

I needed to retune.
removed 2x 330nF, leaving 5uF plus 660nF
Res at 15.2kc/s

blue is the connecting between HV ac trans and HC coil, loose probed.
This is also where the mosfet will connect, leaving only the positive half, then is then switched to neutral.

Green in the current. 5.6A pp and that is only from the HV psu, As I now will not use the HC psu any more (no dc offset, no choke).

The current must be high from the AC coil feeding it voltage (blue).
But this will be disturbed, by the body diode, and the mosfet switch, thus only leaving a quarter wave to feed the resonance.
The parallel resonance thus must be powered by the strong displacement currents caused by the mosfet discharging the high voltage.

What is weird to me, is that the mosfet stays very cool. I had it switching several hundred volts.
lets see how fast that dV/dt is.
And no severe ringing. very clean

Load is fully decoupled. load coil is not even grounded.

I connected the mosfet drain  to the AC coil,
and at the same place, I connected the HC coil with the center tap (bifilar)

Didn't check tuning, seemed to be ok.

yellow (loose probed) HV coil jumps up in voltage at the discharge (orange=gate, when high, AC coil is neutral grounded)

Now the green current is clearly present (probed at HC coil near cap) 2A pp

Blue voltage is quickly high, this is directly probed. 150V

Yellow voltage is around 390V pp but would be around 3x higher say 1kV pp (very low)

The green spikes clearly show the massive displacement current, that are already present at these very low psu settings.

when pushed to higher levels, my audio again crackeled and stopped. I guess I might not have a proper audio ground.

I'll zoom into the discharge voltage to see how fast it is

psu 0.64A 0.9V which is slightly more then previous post
yikes that is fast!
13ns discharge of 250V :shocked:
that is a proper mosfet
So this blue is at the drain, connecting the AC transformer to neutral

Yellow shows the jump in the HV coil. balancing the system.
but we need an unbalance. So now the load coil will be needed, including the ground connection.

I am impressed
 :cool:

This is with the output coil grounded.
only 140V discharge.
HV coil is higher, 950Vpp (x3 is around 2.8kV pp)
current 6.68 A very nice and high.
dont know how much psu I gave, but it was low.

orange and blue are slightly ringing, from the AC that connects to neutral.
I dont have any earth ground so this is fine. the ungrounded pcb is allowed to swing when measuring earth referenced (scope probes are grounded to earth)

load connected.
Now the current drops low. 170mA pp
rest is mostly the same.
altought the HV coil does look like it has less voltage jumping at the discharge.

When I go to higher psu levels, everthing start gliching again.
indication of high radiant displacement currents?

discharge is low. 110V, I have room for another 800V.

Iam not yet prepared to push higher..

but I will need to . the 784 (2kV) is much to low in my opinion.
I would like to see it at 20kV

the current probe also spikes like hell... should remove it.

Also... The phase. 
I switch at zero magnetic current, because the magnetic current is now phase shifted, from being connected ot the load.

MAybe I should also need to check tuning again.

zero current is high reactance, giving high voltage, displacement current is also zero.
so displacement and magnetic current are in phase. this is good.

If needed, could I reduce voltage of the AC coil, at the HC coil?

if the AC coil was a tesla (long) coil then, I could place the primary on the HC coil.
This way it functions more in the quarter wave mode.
still giving out of phase AC on both ends, but mostly at the HV coil side (extra coil)

yes this will be a good solution.
But my precious expensive AC high voltage transformer cant do this.

I would really need a tesla coil with a primary, tuned to such a low frequency.
I could go higher somewhere around 50 kc/s but for a tesla coil that is still very low.
I would need a variable center core to tune it.

vey dodgy, as the high voltage will easily jump to the ferrite core. although I remember using just one iron core, at the base, which was enough to tune it to 60 kc/s hmm...
lets find this coil again.

I should check if changing pin 13 will make me able to get 50% duty

and check the temperature of the mosfet. see if it gets cold

I have the bifilar HC coil connected tot the AC HV coil at the series connection .

and I noticed with or without the load the current is in phase with the voltage .

I need to check of the load is properly connected because normally it phase shifted whereby the current became -90 degrees oit of phase with the hv.

also the ac hc coil now has no direct access to the the parallel capacitor .

I again had a disruption at higher levels
this time I recorded the scope.

it showed the square wave gate ring increase and starting a trigger signal before it was supposed to be high.

this caused the tl494 to retrigger, loosing phase lock, reversing the phase 180 degrees, causing the mosfet to trigger in the negative voltage, which makes it appear as a flatline om the drain.

I do not fully understand
but I feel it is the neutral of the pcb that cant handle the 13ns discharge when the mosfet turns on

I also came to the conclusion I need a tunable ac transformer.

I want to make a tesla coil for this. the primary is to be shiftable. placing it not on the middle and not on one end, but slightly on the first few windings with the goal of giving ac hv on on end (extra coil)
while the other end gives out of phase lower voltage ac for the mosfet drain.

to get the frequency workable low, I intend to place a iron core toroid in the tesla coil at the hight of the primary.

I checked the load, and It was fully connected .
I wonder why there was no phase shift.
is it how the HC coil is connected tonthe ac coil? center tap gives no phase shift?

will reconnect the coil to.check this.

Voltage in phase looks fun but we need them in phase in the load.

So I prefer the displacement current in phase with the magnetic current ,

so both can induce voltage and current in phase in the load coil

I connected the AC hV coil to one end of the HC coil (left side) instead of the (series connection of bifilar).
Again with load, voltage and current are in phase (in this case 180 degrees out of phase)

Is this a tuning matter?

lets compare with the unloaded situation

this is with only the load coil connected to ground (right side) other end open ended.
same psu setting (0.7V)
notice how the values are almost completely the same.
That 120W load seems invisible.
but again this is at very low power settings.

I also want to earth ground the neutral of the circuit to see if it stays stable that way