FluxProbe – measure currents without touching the conductor


flux probe
Flux Probe is a test prod for measuring currents without touching the conductor it is flowing through. More accurately it is measuring the magnetic flux. This way you can measure currents on PCB traces without having to put a resistor in between.
This test gear enables you to trace faults in your PCB (for example search for a short circuit). This is use full for commissioning of you circuit for example.
Do you remember this awe full measuring technique? : Strommessung “in Circuit” In much cases this is not needed when your lab is equipped with a flux probe;-)
FluxProbe – measure currents without touching the conductorThere are similar current probes like this: I-prober 520. The prices of these might make them unaffordable to hobbyists, which is the intended audience for the flux probe tool.

theory of operation

The central part of the circuit is a hall sensor. These sensors detect (static of altenating) magnetic fields. Thus these can measure DC current contrary to coil based measuring principles.
The physics behind these sensors are explained at wikipedia perfectly – so I will spare this part here.

circuit explanation

A part called A1324 (oder similar like A1321) is used for the hall sensor. This one is available in a SOT-23W footprint which enables me to put it on the edge of the pcb.
Because the sensor has a heavily off setted voltage, which is about VCC/2 offset at a used voltage difference of some mV for Amps measuring. This voltage can not be read accurately using multi meters or oscilloscopes. This is why I inserted a offset compensating circuit.

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