The circuit is of the Motorola Linear Databook of 1990. The power source must be symmetrical and the characteristics of the circuit are given next to the diagram.
With this simple tester you can measure the gain of an NPN or PNP transistor. The instrument can...
I found this circuit in an old Argentine publication from 1973. The components are no longer...
Used with telephones at the time, this circuit was found in Popular Electronics from the 90s. The...