From a project coming from 1971.
Instructions :
1) set npn bjt beta to be measured in EC as you wish, for example = 300.
2) start the simulation with the switch opened and adjust the potentiometer at the bottom until the ammeter in oscilloscope show you 0 or the value closest to zero (balanced bridge).
3) close the switch : read the ammeter value in mA and multiply it by 100. This is the beta value searched.
The pot at the top (in real a trimmer) is already adjusted here and in real was to be adjusted only once to regulate instrument using an already beta known of bjt ( a measured sample given).
Real instrument could also works with pnp, inverting power polarity and diode direction via a commutator
