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 TTL digital circuit from Texas Instruments documentation from the 1970s used the company's SN types...
This circuit was found in the December 1984 issue of Radio Electronics magazine. The circuit has a...
This circuit with bass and treble control and 10 W of power per channel is from the SGS manual of...