microammeter

This circuit can be used for current measurements in five ranges, from 1 µA to 10 mA f.s.d. (D.C.). The opamp is used in a virtual earth circuit. The current Ix to be measured flows direct to supply common, and the circuit supplies an equal current from the opamp output through the corre- sponding feedback resistor to the inverting input terminal; the polarity of this current is indif:ated in the diagram.