This circuit was obtained from an Electronics Design of 1964. The circuit makes use of tunnel diodes that are uncommon today. The circuit works with very weak signals.
This is a possible setting for a Colpitts oscillator operating in the audio track. The shunt coil...
We found this circuit in documentation from the 1950s. The circuit basically applies to germanium...
This excellent 3-transistor audio preamplifier is suitable for use with high-impedance...