Hello, i would like to make one.

What is the principle of operation of these devices, showing in attached pictures?

They have passive element from parallel mosfets?

 

Use replacement Elements for an Electric-Stove/Range.
Any other type of High-Power Resistance-Element is crazy expensive.

For testing a Welder, precise Current measurements are not needed,
but immunity from the tremendous amount of
Electrical-Noise that they produce is an absolute requirement.

It's very easy to instantly smoke a big pile of expensive parts with a Welder.
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