Current fine adjustment used with 100ohm 10 turn. 1.5V supply. Use for 4 wire resistance measurement of shunt resistors. In place of 651 mohm resistor place shunt or low value resistor. Adjust the current to 100 mA. Multiply voltage across resistor by 10 to give resistance in mohm. It is usable for 7 ohm down to as low as your voltmeter can accurately measure.