Electronics > Beginners
CurrentSense Comparators for electronic load
RoGeorge:
--- Quote from: Vovk_Z on January 30, 2020, 09:23:53 pm ---May be something like that (here is usual way to make el. load, X4 is for 1k potentiometer):
https://www.eevblog.com/forum/beginners/currentsense-comparators-for-electronic-load/?action=dlattach;attach=918004;image
--- End quote ---
I would like to know how well it performs in practice, what instrument is that schematic from, please?
Vovk_Z:
It works ok, there isn't only additional resistors 1M÷2M from 1.2V to inv. opamp imputs.
And, C1, C2 better increase to 2.2-3.3 nF.
It isn't from instrument, it is classical usual mosfet electronic load circuit. A circuit is from my last project. I made electronic load for myself long time ago but it was made on universal pcb. That circuit was made for my collegue to he could made modern beautiful (Chinese) PCB for me (I don't like making PCB).
RoGeorge:
I didn't suspect it of not working OK, just curios of reading the specs because I wanted to build something similar.
Vovk_Z:
Specs depend on you - you choose mosfet, shunt (and opamp - usual or precision type).
What exact specs do you need to know?
That my module on my last photo with 2xIRFP460 is 250V, 10A, 100W rated. With IRFP460 it works from about 1 V and more.
Kleinstein:
For stability with difficult inductive sources a CC sink may need a parallel RC at the inputs. Depending on the circuit something like 0.1-1 µF and 10-100 Ohms in series could be enough.
The other point is that the circuit runs into a kind of windup, when the DUT voltage gets too low (e.g. not connected). So there can be a significant current peak when connecting a source while the load circuit is already turned on. A diode in parallel to R5, R7 can at least shorten/limit the peak a little.
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