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 was found in a documentation from the 50's. The transistor is made of germanium and...
In other circuits we have seen a circuit for this application whose calculations have been...
This preamplifier is intended for the use with magnetic pick-ups. Power supply must have voltages...