Granted Patent
Utility
US 4,621,225 · App. 06/577,218
Passive transformerless battery charging circuit
Inventor:
Daniel J. Birk
Patented Case
View Patent ↗
Granted: Nov 4, 1986
Filed: Feb 6, 1984
Inventor
Daniel J. Birk
Assignee (at issue)
Pittway Corporation
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.