The indicator for this circuit is a 0 to 1 mA milliammeter. The operational is from the 70s, when the circuit was published. Modern equivalent can be used.
Found in a 90s Popular Electronics, this circuit allows to select the operating ranges between...
This circuit was obtained in a 1960 transistor manual from Sylvania. The circuit uses small...
This simple unijunction circuit is from a Radio Electronics from July 1963. It can be assembled with a...