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.
This circuit was found in a 1975 documentation. Current general-purpose transistors can be used,...
We found this circuit in a publication for radio amateurs in 1974. The bipolar transistors can be...
This conventional humidity or water alarm circuit was found in an English documentation from 1974....