This 1967 General Electric circuit makes use of an array of 3 (integrated) transistors for an amplifier stage. The circuit has a 500 mV output.
This circuit is from an American magazine that no longer exists, Modern Electronics, in a February...
Found in a 90s Popular Electronics, this circuit aims to find the voltage of a zener diode up to...
Found in a Popular Electronics from the 90s, this circuit is suitable for testing and tuning...