Xenotime, Librarian of Æther 16h ago
Any electronics people know a simple/cheap circuit to precisely measure current but have the measured side be dc isolated (it’s biased at 30V)?

my naïve thought is to just have a good shunt into a like difference circuit with an op amp and resistors and then an ADC can read that

is there a better way to do this?

edit (clarification): some folks picked up on this but I need to measure pretty small currents (<100uA) sensitively so magnetic sensors probably are out. thanks for all the ideas!
Show threadlumiya

@xeno
Another option that might be interesting would be magnetic based sensors.

This article is designed to sell you those. But could be a start. (Other manufacturers exist this was just the first link I found)
https://www.allegromicro.com/en/insights-and-innovations/technical-documents/next-generation-current-measurement

One big drawback is that strong external magnetic fields do influence the result.

Those as well as the shunt based sensors do have fully integrated options. As well as some with an integrated ADC and digital interface.

Next-Generation Current Measurement - Technical Article | Allegro MicroSystems

Introducing the Next-Generation Current Measurement Series: Advanced magnetic current sensors accurately detect magnetic fields generated by current flow, offering precise current level measurements.

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