With this circuit it is possible to vary the resistance by adjusting the mark/space reaction of the 555. The circuit was found in the November 1989 Radio Electronics magazine.
Found in an Electronic Design from the 90s, this circuit does not need sinks for its components. The...
The figure shows a way to apply gain control to the LM3600 OTA. The circuit is from a Radio...
This circuit was found in a 1968’s General Electric documentation. The circuit has a control range of...