This circuit lets through the 300 Hz to 3kHz range that corresponds to the human voice. We found it in the Radio Electronics magazine of February 1990. The circuit uses both parts of the LM381.
This dual balanced modulator configuration was obtained in a 1980s telecommunications...
Found in Linear Technology documentation from the 90's, this circuit mixes two analog video...
This voltage controlled oscillator, which can be used as a shield, generates signals in the 1.5...