This circuit was found in American documentation from the 90's. The circuit applies to any operational. The power supply can be between 5 and 15 V depending on the operational.
This VCA was found in the July 1988 issue of Radio Electronics magazine. It uses an OTA op amp and...
Found in US documentation, this circuit changes the waveform and phase of a sine signal. The...
Found in an American amateur radio documentation by the name of “antennascope” this circuit is...