The figure shows a way to apply gain control to the LM3600 OTA. The circuit is from a Radio Electronics from July 1988.
Found in an old Radio Electronics, this circuit applies to frequency meters for frequencies up to 100 MHz....
With changes, this circuit from a documentation of the 70s, can be adapted to use more modern...
I found this circuit in a July 1982 English magazine. The circuit is still viable by simply using...