Kapanadze Cousin - DALLY FREE ENERGY

[verpies]

What do you mean "that's all I have".

That's your only adjustment for adjusting pulse spacing.

I don't have a normal scope signal if I only connect the scope to ONE channel of the two #9 and #10 pins, and ground.
The TL circuit and drivers work as I had shown on the video, ONLY, if I place BOTH scope probes on the 9 and 10 pins, and ground.

Maybe your scope is triggering from the other channel.

I burnt up two more fets last night while looking into the problem, which is what is making them overheat in seconds. I'm sure the problem is  something simple...

MOSFETs burn up because of excessive drain current or Drain-Source overvoltage or Gate-Source overvoltage.  To help you at a distance we need I_D vs. V_DS scope shots like we asked for.

[NickZ]

   OK,  we'll maybe I can take some scope shots next week when I get some more mosfets to burn.
I the meantime I'll try to find the problem.
I think that the problem is in the TL circuit itself, and not with the rest of these device or components.

[TinselKoala]

That's your only adjustment for adjusting pulse spacing.
Maybe your scope is triggering from the other channel.

Yes, if the scope shows the nice clean waveforms seen in the video when both probes are connected to 9 and 10, but doesn't show the corresponding single waveform when only one probe is connected... the scope is probably set to trigger on the disconnected probe's channel. Set the "INT" trigger switch to the correct channel in use, this will probably clear up that problem.

MOSFETs burn up because of excessive drain current or Drain-Source overvoltage or Gate-Source overvoltage.  To help you at a distance we need I_D vs. V_DS scope shots like we asked for.

Also they can overheat and burn out from overheating due to spending too long in the high-resistance linear region, meaning it is not getting enough current and/or too low a gate voltage from the gate driver to fully turn on the mosfet. This usually takes a bit longer to burn them out though. I have tested IRFP260n mosfets and they still work even when hot enough to melt the solder connections, so this probably isn't the cause of Nick's burnouts, but it should be checked anyhow.

[TinselKoala]

   OK,  we'll maybe I can take some scope shots next week when I get some more mosfets to burn.
I the meantime I'll try to find the problem.
I think that the problem is in the TL circuit itself, and not with the rest of these device or components.

The clean waveforms you showed in the video, with dead time (duty cycle)  and frequency adjustment, indicate that the TL494 is working properly, or at least it is doing what you want, and it is outputting the correct signals to drive the Gate Driver chips.

So when you can make new scopeshots, please do two sets: One with the probes on the outputs of the Gate Driver chips, and one with the probes on the Drains of the mosfets. Both sets referenced to ground, that is, the mosfet Source connection. 

You might also try using IRF3205 mosfets since they have lower on-state resistance and require less gate charge to turn on.

[apecore]

   OK,  we'll maybe I can take some scope shots next week when I get some more mosfets to burn.
I the meantime I'll try to find the problem.
I think that the problem is in the TL circuit itself, and not with the rest of these device or components.

Nickz,
I guess your fets get burned by to high Vds peaks....this was in my TL start-up situatiion the case.
I would advise you for the timebeing to use some bigger snubber caps.......20-30nf.
So the Vds will stay below the 240V
Use your scope to monitor the Vds...as Verpies mentioned.
You wil see what happens while tuning the D/C pot.

Greetings