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 is the commercial circuit for the TRF-44 amplifier sold in Japan in the 1960s. The circuit...
This circuit uses a common cathode display and TTL integrated circuits. We found it in a 2001...
This circuit was found in a 1992 publication, using an operational amplifier not very common...