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This induction heater is based on the popular “Royer induction heater” schematic.

Changes made to the design include:

Higher rated MOSFETs
Bigger Zener diodes
RC filter on the Gates
Flyback Diode (D8)
Gate resistors to limit ringing (R8, R9)

In short, all of the changes help to improve the durability of the induction heater. It has been reported with the original design, often the MOSFET gate’s would be damaged from flyback after extended use. To be fair, I haven’t tested the circuit without my additions so I can’t confirm or deny this. Gate resistors have to be added as ringing was quite a problem without them. The ringing would cause the MOSFETs to become quite hot & this can lead to premature failure. With the addition of a pair of 18R gate resistors. The ringing was reduced to an acceptable level.

2x Wakefield-Vette, 694-50 Heatsink Click here
2x IRFP4668PBF MOSFETs Click Here
10x WIMA, MKP1J034706B00KB00, 470nF, 630VAC Capacitor Click here
2x 2.2uF Ceramic 100v Capacitor Click here
2x FR307 Fast Diode Click here
2x 47R, 5w Metal Oxide resistor Click here
2x 470R, 5w Metal Oxide resistor Click here
2x 12v, 5w Zener Diode Click here
2x 100uH, 15A inductor Click here (see below for details)
2x 10k, 1/2w resistor
1x 4.7k, 1/2w resistor
1x 5mm LED of your choice (power indicator LED)”

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