This commercial circuit is from a Japanese magazine from 1967. It uses germanium transistors, and the coil can be made with 80 to 100 turns of fine enameled wire on a ferrite rod.
The purpose of this circuit is to add millivolt scales to a common multimeter. Used transistors are...
I found this circuit in an old Argentine publication from 1973. The components are no longer...
The circuit is from the National Semiconductor Linear Applications Handbook published in 1994. The...