This squelch circuit used in transmitters was found in a magazine for radio amateurs 73 in the 1980s. The circuit admits equivalent components.
This circuit works with small 5 V incandescent lamps but can be modified to operate with LEDs. The...
Found in Linear Technology documentation from the 90s, this circuit uses an operational amplifier...
The tone produced by this circuit depends on the capacitor and the adjustment of the...