This silencer or squelch preamp circuit was found in a documentation for radio amateurs. It completely mutes the circuit when there is no sound picked up by the microphone.
The integrated circuit used in this project is unusual. We found this configuration in Motorola's Linear...
This circuit with only one transistor was found in Japanese documentation from the 1960s. The...
The operating frequency of this circuit is 465 Hz and the input voltage is 12 VAC. The circuit is...