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 nonlinear gain circuit was found in a 1965 Electronic Design. The configuration can be used...
This circuit is from an English documentation from 1969. The circuit can be designed based on...
This circuit, with adjusted sensitivity, can use common general-purpose transistors. The circuit is...