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 generates a pulsed tone whose frequency depends on C2 and whose flashing depends on...
This circuit of a Popular Electronics from the 80's selects tones around 60 Hz, acting as a filter...
This circuit samples the current in a load and in case of excessive value it activates a...