I want to build this induction heater but the picture seems to include two more resistors that are not in the schematic. Also even though color markings on the resistors are visible, they don’t seem to match what is in the photo of the finished devise.
can anyone submit probable values of the 4 resistors? I think there is only two values. One for what I believe to be pull down resistors and the other showing in the schematic as 220 ohm but the color markings don’t agree.
Appreciate an opinion
Thanks

 

I see two 10K and one 6.8K and one obscured resistor. The diodes do not appear to be connected as in the schematic.

 

The diodes appear to be cross-coupled from one drain to the opposite gate, so I'd suggest that D1 should connect to the blob next to R2, not to R1.

 

I see two 10K and one 6.8K and one obscured resistor. The diodes do not appear to be connected as in the schematic.

Yeah, I thought the two resistors from the gate to the source pins on each mosfet were 10K(pull up) too (but not on the schematic. The other two are the same also weso if you think 6.8K then the other one is a 6.8K. Odd that the schematic has 220 ohm resistors?
I’ve tried to get a message through to the YouTube channel “SR Electronics 2.0” but no joy….like this pic is not the project that goes with this schematic

 

I suspect that it isn't a very good circuit. If I wanted to use a MOSFET at the sort of frequencies an induction heater would require, I'd be using a gate-driver IC.

 

The diodes appear to be cross-coupled from one drain to the opposite gate, so I'd suggest that D1 should connect to the blob next to R2, not to R1.

The cross coupling seems correct to me, so perhaps the schematic is wrong.

The 220 might have been correct for BJTs and changed to 6.8K for MOSFETs.

 

The cross coupling seems correct to me, so perhaps the schematic is wrong.

The 220 might have been correct for BJTs and changed to 6.8K for MOSFETs.

That makes sense, you wouldn't use a gate driver with a BJT. The BJT would probably be something like a BU208 horizontal deflection transistor

 

The diodes appear to be cross-coupled from one drain to the opposite gate, so I'd suggest that D1 should connect to the blob next to R2, not to R1.

This is a pretty standard schematic for a simple heater. The resistors here are clearly marked and

 

View attachment 368408This is a pretty standard schematic for a simple heater. The resistors here are clearly marked and

Other components are clear

 

Royer style ossilator the most popular for small units.
Also L1 can have low turn secondary if needed, If doing repeated operations copper tube with water cooling may be needed.

 

Also, your oscilator frequency is decided by the mass of the parts to be processed.
e.g. Very Large steel plate would be as low as 60hz on a industrial opperation.