This circuit was found in a 1967 US documentation. It shows how to build a gain control by digital signals. The circuit can be used as a shield. FET can be a modern equivalent.
This circuit was found on a Radio Electronics of July 1984. It consists of a source with the 741...
As part of a larger project, we found this modulation meter in the August 1994 Electronics Now...
Found in an American documentation from 1968, this circuit senses the temperature through an...