This circuit serves as an audio output for AM or even FM radios and was found in a Radio Electronics magazine from March 1990. Note the supply voltages.
We found this circuit in an American 1980s documentation, but it can be implemented with modern...
This circuit was found in a 1968 General Electric documentation. It has an input impedance of 2 M ohms...
This circuit appeared in a noverber 1962s Practical Electronics. The magazine is no more, but the...