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 shield circuit was found in an American publication from the 80's. The triac is of low...
In this circuit of a 1978 publication, the noise generated at the collector-base junction of any...
This circuit is from a year 2000 documentation. It generates pulses as fast as a battery or as...