Granted Patent
Utility
US 4,717,889 · App. 06/902,934
Power control system for periodically and selectively energizing or shorting primary windings of transformers for controlling the output voltage across a common secondary winding
Inventor:
Rudolph H. Engelmann
Patented Case
View Patent ↗
Granted: Jan 5, 1988
Filed: Sep 2, 1986
Inventor
Rudolph H. Engelmann
Assignee (at issue)
Electro-Voice, Inc.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.