A DIY Fluxgate Magnetometer based Current Probe

shabaz @ element14.com show us how to build a Current Probe based on DRV425 Integrated Fluxgate Magnetic Sensor IC. He writes:

Current measurement can be really awkward when working with circuits. Voltage measurements are (usually) straightforward, but when it comes to current measurements the story is different. One typical approach is to insert a known resistance by breaking the circuit, and then measuring the voltage across it. This is difficult if one end of the resistor is not at ground potential, because oscilloscope probes are (usually) designed with the ground leads all connected together, and it will damage things if the grounds of different channels on the oscilloscope are connected to different parts of the circuit.

This project describes a very sensitive home-made current probe that doesn’t require a known resistance to be inserted. It has not been fully characterized but the initial results are reasonably promising. It was tested at currents of the order of single-digit microamps up to 10mA (it can be assembled for higher current ranges if desired), and it functions from DC to around 20kHz, and is fully isolated.

A DIY Fluxgate Magnetometer based Current Probe – [Link]

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