This circuit was found in a 90’s 303 Circuits. The components are from the period and the heating system depends on the resistive element.
This circuit with transistors was found in an old Japanese publication, translation of an American...
This 8 W amplifier with germanium transistors was found in a Japanese documentation from 1967. The...
This circuit of the 80's makes use of components of the time. The circuit is from an American...