This Linear Technology circuit can measure currents from 100 pA to 100 uA. The circuit is from the 80's, using a component of the era. Transistors are general purpose types.
This circuit simulates the effect of an inductance. Equivalent operational amplifiers can be used,...
This circuit generates quadrature signals in frequency that depend on the 18 pF capacitors. These...
This control of DC motors for currents up to about 200 mA was obtained in an American publication of...