This circuit was found in an English publication from 1967. The circuit is for listening on a phone. Transistors are types of germanium of the time.
The integrator in the figure is characterized by low input current and is based on an LM101A. C1...
This circuit was found in an ancient American documentation. The integrated circuit is of the time...
This circuit, from a 1976 documentation, amplifies signals from 100 Hz to 600 kHz with a voltage fan...