Patents by Inventor Thomas G. Harrigan

Thomas G. Harrigan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Circuit for regulating a DC voltage on which a large AC voltage is superimposed
    Patent number: 4156150
    Abstract: Disclosed is a ringing power supply for developing a ringing signal having an AC voltage combined with a regulated DC voltage, of magnitude smaller than the magnitude of the AC voltage, from a source having the AC signal combined with an unregulated DC voltage. The ringing power supply comprises a control circuit responsive to the AC and DC voltages of the source for developing a replica signal of the regulated DC voltage with its superimposed AC voltage, and a regulator responsive to the developed replica signal and to the source for providing the desired ringing signal.
    Type: Grant
    Filed: December 16, 1977
    Date of Patent: May 22, 1979
    Assignee: Bell Telephone Laboratories, Incorporated
    Inventors: Thomas G. Harrigan, William E. Jewett, Jr.