Kapanadze Cousin - DALLY FREE ENERGY

[Void]

Hi Itsu. Ok thanks for the info. So your series RC snubber is similar to
what I ended up going with as well. Your switching overshoot spikes were
similar to what I am currently getting as well. Hopefully the info I provided to Nick will
help him to solve his problem with resistor overheating in his series RC snubbers,
as I am also using IRFP260 MOSFETs right now. I will experiment further with that Allega
snubber setup again and see if I can get it to work for me to limit those switching overshoot spikes.

P.S.
Nick: I think you use Mouser.
Here is a link to Mouser for 2 Watt carbon film resistors, filtered for resistances in the
range of 50 ohms to 1 kilo ohm. I think these should be suitable for use in snubbers.
If you want to help reduce hassles of possible burnt resistors, use two, 2 Watt resistors
in series to make up the total required resistance value you want. That way the combined series
resistors will be able to dissipate up to 4 Watts. For example, if you need a resistance of say around
200 ohms,  then use two, 100 ohm 2 Watt resistors in series to make two hundred ohms total.
Then you will have the equivalent of a 200 ohm, 4 Watt resistor.
Mouser 2W Carbon Film resistors

All the best...

[NickZ]

  Void:
   I've been using some of those 2 watt carbon film resistors in the snubbers, but it didn't make any difference. Those resistors get just as hot, and perform the same as the smaller carbon one, as far as I can tell. I've already tried doubling them up, both in series as well as in parallel at the same time, which also did not help much with the snubber heating issue. In any case, my fets are staying reasonably cooler, but it's at the expence of the snubber resistors which take up the shocks.

   Jed made a video about his problem with the snubbers also not being able to bring down the spikes. You may want to see that video. He also made a lossless clamp windings for his yoke, which also did not help much with bringing down the spikes. You can look for it on YT. After that he seems to have given up on the device, and has not posted any more on this thread.

  The HV impulses from the Kacher circuit rides on the magnetic induction circuit's wave form. So, I think that some ringing is needed on the tops of the square wave and not just a clean flat top square wave signal. Or like Itsu you may end up with a clean 100v square wave signal that does absolutely nothing to provide any additional output at the bulbs when the Kacher is also on.
However, if the peaks aren't tamed to run under 200v, the fets won't last, either. So, there has to be a balance of heating between the fets, and both snubber circuits. Or which ever one gets hotter first, will go up in smoke, and that's all she wrote.
My snubber resistors start to smoke in 1 minute's running time. The more load I add the hotter those resistors get, as the voltage goes higher and higher, with each additional bulb added, to over 350v with NO snubbers on. And that's why I've burnt a pile of fets, previously. And that's why I bought a bunch more of them, just to be sure that I have enough of them, to not worry about risking frying a few more.

  Itsu: That last scope shot of mine is showing the device signals while running in the best resonant frequency, which I can find to tune it to. And it does add some increased gain to the 3t coil's capacitor circuit's output when the Kacher is also on, as well.

[Hoppy]

Nick,

Try small incremental changes to the 3-turn yoke circuit capacitors whilst monitoring the heat on the snubber resistors. The energy transfer to load needs to be optimised, otherwise the energy just gets dissipated in your components as excessive heat. If as you say, by adding load the spike voltage increases, it suggests that the impedance of your series resonant yoke circuit is being progressively mis-matched to the load impedance. Optimal matching is either achieved by altering the source impedance to match the load impedance or vica-versa. In your case I think changes are needed to the value of your yoke circuit caps, such that there is optimised impedance matching to the load you wish to drive.

[NickZ]

  Hoppy:
  The problem is that the better optimized the 3t/cap circuit gets, the brighter the bulbs are, and the higher the heating on the snubbers. And not the other way around. Using a 50w bulb, or even a 10 to 20w bulbs, there is little heating, but that's not the results that I'm after. I need to get all 3 or my 200w bulbs going at once, at least like I showed on the video, when one of my fets blew, at least.  But, without blowing the fets.

[Void]

Hi Nick. Ok on that. Just for comparison purposes to my own test setup, what value of C and R
were you using in your series RC snubbers when you posted your previous scope shots? Also, were
you using the Allega snubber as well when you made those scope shots?
All the best...