Based on an LM36000 OTA this circuit was found in the July 1988 issue of Radio Electronics magazine. It covers frequencies in the range of 45 Hz to 45 kHz.
This circuit uses an unusual electromechanical component: a mechanical blade resonator. The...
Found in a 1969 documentation, this circuit is reset by a push button. The activation time is 100...
This squelch circuit used in transmitters was found in a magazine for radio amateurs 73 in the...