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 is the well-known lightning lamp that was published in the March 1988 issue of Saber...
Found in a 1980s documentation, this amplifier uses an operational aplifier of the time with two...
This circuit was suggested by Signetics in a 1980s documentation. The operational is old, but the...