This circuit with output powers of 2 to 3 W depending on the power supply was found in the magazine Radio Electronics of April 1990. The speakers are 8-ohm.
Found in a 1967 Electronic Design, this transistorized circuit compresses and then expands a pulse....
This squelch is activated by its own noise, acting automatically. It is used in communications...
This is the battery-powered version of the previous circuit. The circuit is from the same Radio...