This circuit was found in documentation from the 90s. The operational amplifier is NE5514, which is uncommon today. The configuration can be adapted to use modern components.
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...