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 obtained in an American documentation translated in the 80's. The circuit can be...
This circuit is from a 1998 Electronics Now and can be easily assembled since it uses a common...
This circuit was suggested by National Semiconductor in its Linear Application Handbook. The...