Hi Itsu,
The signal up and down in the drains is caused by 28 turns and 12+12 turns coils from the yoke.
 The way you wound that coils tell me that 28 turns have influence for 12+12 turns and you have a strange signal in the drains.
Maybe you must have one coil up to another. Is just my supposition
 Have a load for 28 turns coil and see the signal in drain.

  Itsu:
  Good to see you're still working hard on all of this.  I didn't know if you were still in the game.  Yes, No?  Looks more like... Yes.
 
  My inductor on the grenade also heats up, as well as the yoke. Although the fets stay fairly cool, even without fans or heatsinks.
 
   Do you find any benefit in using your home made TL circuit, compared the the ready made board that you bought through Ebay?
 As I'm still considering going that route myself, with the ready made TL board, in an effort to un-complicate things, if possible.
  I guess that there are no commercial mosfet driver circuit that can also be implemented in this case, to drive the IRFP260N?
 
   As there's been a lot of discussions about the mosfet snubber circuit, and which one to use. Is there one that you would still recommend to use along with the commercial TL board?

  As different loads can give different scope readings, and can also affect the shape of the wave forms. Maybe try some other bulbs on as well, to see if there's any difference in the wave form shape, and just how many of those bulbs it can light. Which would give some idea of the output power that those drivers can provide.

  Thanks for sharing your video, and ideas.
                                                                  NickZ
 
   

Dog-One,  Jeg,

that is basically the same snubber setup as in Olegs green box setup, he has only 1 resistor while you have 2, see blow up below (ignore the red circle).
I tried it but it did not work for me, i still had massive ringing (1.4MHz) when the MOSFETs shuts off.

It would be good to see if Jeg has better results

Itsu.
I have the same results with you. I mean that with allega's snubber, oscillations still exist. It is just that it cuts the first higher peak of the oscillations down to half value than without the snubber.

Your result using the snubber calculator is remarkable. I will try to do the same. Don't you think that a diode is missing from your drain? (cathode to drain anode to source)? It will ground the negative peaks as they can't be grounded through your tvs combo. I think.

I just looked at your video. It looks like what d1 described earlier. Your gate opens earlier than it should. This is because it sees a negative spike at its drain. Negative spike is being produced due to the positive front of the other mosfet.  Perhaps a diode as I told you before between drain and source can help.

Itsu.
I have the same results with you. I mean that with allega's snubber, oscillations still exist. It is just that it cuts the first higher peak of the oscillations down to half value than without the snubber.

Your result using the snubber calculator is remarkable. I will try to do the same. Don't you think that a diode is missing from your drain? (cathode to drain anode to source)? It will ground the negative peaks as they can't be grounded through your tvs combo. I think.

Hi Jeg,

the linked website to the RC snubber only mentions the RC, so i already added the Bat 46 diode across the R.
I know what you mean by adding another diode across the drain source, but thought it would not be needed.

But i did anyway now (another bat46) from cathode to drain and anode to source (so parallel to the internal MOSFET body diode) but it did not change the signal nor the behaviour with the gate lagging the drain 

I just looked at your video. It looks like what d1 described earlier. Your gate opens earlier than it should. This is because it sees a negative spike at its drain. Negative spike is being produced due to the positive front of the other mosfet.  Perhaps a diode as I told you before between drain and source can help.

i don't see that "Your gate opens earlier than it should", the scope screenshot  shows that the gate is not open yet while the drain is already on (if you know what i mean) 
And i don't see on the scope this "negative spike at its drain".

So somehow the drain is being activated by something else than its own gate
 
Thanks for your remarks.


Itsu

Itsu, how is your drain climbs at 72v while your tvs clamps at 54v? 

Itsu, in addition the diode in parallel with the resistance at your snubber, is upside down compares to akula. Check this in case..

Thanks skywalker66,

bucking mode, hmmm the primaries are both wound the same way (cw) does that put them in bucking mode?

And if they are in bucking mode, would that not eliminate most of the flux, rendering the secondaries almost useless?
They are certainly not useless at the moment.

I will double check on that once more,   thanks.

Itsu

I can't tell for sure from your video, I may misinterpreted your connections, maybe you can check this issue.
quote:
<And if they are in bucking mode, would that not eliminate most of the flux, rendering the secondaries almost useless?>
yap ! you right.