AZL Book: Electrical Math - Measuring Current with Analog Voltage Input

in #azlbookslast year


This circuit can be used to measure the current going through a load, using an analog voltage input. This is a pretty specific case, but at one point I was stuck with a full DAQ chassis and no analog current inputs available, only voltage. I came up with this so I could measure load current without having to modify my DAQ configuration.

This is based on Kirchoff’s current law, essentially stating that the current at all points in a closed loop will be the same. In other words, the current through the load in this diagram is going to be the same as the current through the resistor. Now, if you go too high in resistance, you’ll have a more significant impact on the current (the current in the loop will be higher because of the resistor), but if you go too low you’ll have a wimpy little voltage drop that can’t easily be read…so this has to be optimized on a case by case basis, but could be handy if you’re ever in such a pinch.

Thanks for checking out some more of my work! As always, I hope you enjoyed witnessing as much as I enjoyed creating!

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