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400V/10A-100W mini dynamic electronic load

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--- Quote from: blackdog on April 16, 2023, 07:22:00 pm ---Hi,

The speed of your current loop depends on your opamp, the MOSFet used and your compensation.
The LT1014 is not a fast opamp but your compensation with the 10nF capacitor might be a bit too much.

A buffer behind the current loop opamp usually helps, so the opamp sees a much lower load and you have more current to drive the Gate properly.

Keep in mind, that the buffer should be wideband enough.
I still have a small collection of LT1010 buffers lying around that I then use for that kind of application.

Not everyone has a collection of IC buffers in stock, but for experimentation you can also put the two opamps of the NE5532 in parallel.
Those then come inside your DC loop of the opamp.
Because of this, you will not suffer from offset errors of the NE5532, resulting in at least 60mA of peak current for the Gate of your Mosfet.
You will have to experiment with the 10 Ohm resistor, and the combination of 3K3 and the 10nF capacitor.

Make sure you pay attention to the build-up, especially if the MOSFet is reasonably fast.
You may need a Snubber from the Drain to the ground point of your 0.1 Ohm resistor.

Happy experimenting!  ;)

Kind regards,

--- End quote ---
Thanks for the input.

So how this project goes on?
Worth repeating or not yet?


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