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.
We found this circuit in the May 1996 Electronics Now magazine. The relay must have a voltage...
The shield circuit shown is from the 1994 Linear Applications Handbook by National Semiconductor of 1994....
Up to 0.5 A DC motors can be controlled by this circuit. Direction change is achieved by a logic...