In this video, we demonstrate using a Mazilli or Royer oscillator driver with 100 nF resonant capaicutor and using IRFP260N and MOSFETS to drive a gapped ferrite core at a resonant frequency of 218 kHz. At this high frequency we can heat small metal objects very quickly. This will allow braising of small metal parts. This is especially useful in jewelry and in annealing brass cartridges from spent ammunition. Typically, approximately 60V DC from a SMPS will work great, but also AC from a variac can be used. The video here demonstrates the heating effect of the high permeability ferrite toroid with a small gap cut in the ferrite to reduce ferrite heating and cracking.
There is a tradeoff between permeability of the gapped ferrite and heating of the ferrite versus heating of the workpiece.

The gates of the MOSTETs are powered separately with 12 V wall adapter.

Schematic:
https://drive.google.com/file/d/1U3Cp...

Latest Gerber:
https://drive.google.com/file/d/1vwFN...

BOM:
https://docs.google.com/spreadsheets/...