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 circuit was found in the June 1985 issue of Radio Electronics magazine. The idea is to use a...
Two inverters, of the 6 available in a Low-power Schottky 74LS04, are used in this anti-ring...
The capacitors on this circuit determine the frequency that this circuit can detect. We can adapt...