This circuit was found in a 1970 IEEE publication. The circuit functions as a voltage controlled variable resistor and can be used with audio signals. Transistors admit current equivalents.
This circuit was found in a 1992 publication. The circuit uses common components and includes the...
The traditional circuit was taken from a French magazine Radio Plans that no longer exists but can...
The amplifier shown in the figure is characterized by the very high input impedance, given by the...