Full Title

Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems > Regulating voltage or current (G05F1/02 takes precedence) > wherein the variable actually regulated by the final control device is DC (G05F1/625 takes precedence) > using semiconductor devices in series with the load as final control devices (G05F1/461 takes precedence)