lw1ecp
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I need to measure the current on the power transistors of a resonant induction-heater generator. I know the current towards the load is quite sinusoidal, and expect a half-wave at the drains or sources. If I use a 0.1 ohm shunt built with 18 paralleled resistors, 1.8 ohm each, I get an oscillogram close to the ideal. But if I use a homebrew 0.1 ohm four terminal shunt built with a few millimeters of nichrome wire, the wave is GROSSLY distorted!. The anomaly is not related to self inductance. The same happens with a few centimeters of plain iron wire, with non inductive winding.
What is going wrong?. If this is not known to you, I can post some photos. I am not speaking about ringing at the beginning, nor common-mode coupling into the scope.
Or: what are the commercial alternatives?. The peak current is 30A at 50kHz, I may soon need 100A at 200kHz.
Thanks!
What is going wrong?. If this is not known to you, I can post some photos. I am not speaking about ringing at the beginning, nor common-mode coupling into the scope.
Or: what are the commercial alternatives?. The peak current is 30A at 50kHz, I may soon need 100A at 200kHz.
Thanks!