This circuit was found in a 1968 General Electric documentation. It has an input impedance of 2 M ohms and excites a load of 16 ohms. The integrated circuit of the time is the PA237.
This circuit with transistors and a crystal microphone appeared in Radio Electronics magazine in...
This is one of the first radios with an integrated circuit. The circuit is from a Radio...
This circuit is from a Mallory 1968’s documentation. The integrated circuit is of the time and the...