This circuit uses a common multimeter on the voltage scale. The calibration of the scale should be done based on transistors with known gains.
We found this circuit in an American publication from 1977. Operationals can be type 741 with...
Found in an American 1980s documentation, this circuit makes use of a sensor of the era uncommon...
This somewhat unusual configuration, mainly in the form of adjustment, is from a 1978 publication. The...