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 is suitable for calibrating old oscilloscopes. It was found in a 1980s documentation. It...
This circuit was suggested by the Texas Instruments optoelectronics manual. The same configuration can be...
This extremely compact circuit was obtained in a 1967 Japanese documentation. The original...