We find this circuit in an Electronics Now. The indication of the logic level is done on a 7-segment display according to the connections given in the diagram.
This circuit was taken from a Popular Electronics from the 1990s. The circuit triggers a relay that...
Found in a Popular Electronics from the 90s, this theremin is played by the position of the hand...
We found this circuit in a transistor manual from the 1960s. The transistor is the Germanium...