This VCA was found in the July 1988 issue of Radio Electronics magazine. It uses an OTA op amp and has its gain adjusted by the voltage at the gain input.
This circuit can be used as an answering password system in a store, office, or other location....
May 2016 - Mouser Electronics already have to deliver the new integrated circuit Maxim MAX14724. It...
Found in a 1965 Motorola documentation, this circuit uses a neon lamp as a trigger element. The SCR...