The circuit shown was found in an American documentation from 1964. The circuit uses transistors of the time and the indicators are small lamps.
This transistorized receiver was found in Popular Electronics from February 1968. Transistors are...
This sound effect circuit was found in a 1987 publication. It is a circuit that drives a set of...
The circuit shown is from 1997 Linear Technology Applications. The components used were common at the...