We found this circuit in a Japanese 1968’s documentation. The circuit makes use of transistors from that country common at the time of publication. Observe the symmetrical power supply for the circuit.
Using LM3909 integrated circuits, this circuit was found in an American documentation from the...
This circuit was found in an ancient American documentation. The components of the time are not...
This circuit with low impedance output and 900k input impedance was found in the October 1993...