ZVS induction heating coil

I made a small induction heating coil with a normal ZVS Mazilla driver.
IRFP260 Mosfets.
Did trial and error with a variety of coils.
At first I used an 5 + 5 to 12 turns isolating transformer which didn't work at all, then decided to wire a 4 + 4 direct coil onto the ZVS which worked well but very rapid heating of the mosfets.
A 6 + 6 coil works pretty well.
Copper work coil made of 2.5 mm² Ø solid wire.
A normal square headed screw heats up to curie point in about 10 seconds.
( 4mm² Ø )
The heating on the work piece starts from the center point of the coils and goes to the outer ends.
Interesting to note is that a thicker piece of iron yields a larger current in the driver circuit.
The 6 mil² steel rod destroyed one 10 Amp and a 16 Amp HRC fuse and one of the IRFP260 mosfets.
The latter was replaced with an IRFP250 and works well.
The voltage cross the driver is about 1 Volts with a 5 + 5 heating coil and about 50 Volts with a 5 + 5 drive ( 1mm² ) coil into the TV flyback transformer.

Operating frequency is about 100 kHz.

TV flybacks do output very High Voltages, and have to isolated and shorted out, to discharge the internal Capacitor to prevent an electric shock.

Thanks for watching.

A bit more R & D is needed to improve the design, but for the time being I am pleased with the results for now.
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