Electronics > Beginners
Using opamp to sense current over a shunt in both directions ?
Renate:
--- Quote from: Vovk_Z on January 24, 2020, 09:08:31 am ---Item on the photo looks like automotive fuse...
--- End quote ---
That's because it is.
This is my setup, the fuse has a resistance of about 0.5 milliohm.
I use it as current sense shunt.
That way I don't need extra wiring or separate shunt.
Yes, I had to calibrate it.
I'm planning on upgrading the INA219 to an INA226.
I just have to disconnect the tiny wires, not disturbing anything.
I can even run both the old and the new sensor at the same time to check calibration.
Zero999:
Did you calibrate it at different currents? The fuse's resistance will quite likely have a significant positive temperature coefficient. If you've not taken that into account, I doubt it's worth using a supper accurate sense amplifier.
Renate:
--- Quote from: Zero999 on January 25, 2020, 05:25:05 pm ---The fuse's resistance will quite likely have a significant positive temperature coefficient.
--- End quote ---
Oh, I presumed that it would have some sort of temperature coefficient.
The main reason for using a better ADC would be to have a standard breakout board for other projects that use real sense resistors.
For this specific case getting something with a lower / more stable offset will be useful.
I'm more concerned with whether the electrons are going in or out.
Absolute accuracy is not that critical.
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