This project is a derivative of a uCurrent project by Dave Jones of EEVBlog.com.
He designed a circuit to measure nA and uA without the problem of burden voltage.
Special Thanks to Dave Jones for providing free schematic and board layout.
This device is a must have for a home lab. It can be very difficult to measure very small or very large currents.
I have duplicated Dave's design and I've added my own high current circuitry capable of bidirectional current up to 100A using a Hall Effect series current sensor.
This whole box will be powered by 2) 18650 Lithium-Ion cells. I like the bannana plugs he's using, I'd also like to add a BNC for directly connecting to an Oscilloscope and have the output = 1/10th the actuall current that way the O-scope can be set to a 10x probe to compensate.
2) 18650 cells have a max voltage of 8.4v and a minimum safe voltage of 6.0v. So the actually voltage range will be limited to 10x the actual battery voltage = 60-84A which should suffice for most application.
The high current sensor is bi-directional and the output at 0A = 2.5v (1/2 of Vdd). So the output of the high current sensor will be a differential signal (+) = Vout and (-) = 2.5v constant. After gain the output will be 100mV/A.