Patents by Inventor Charles R. Griffiths

Charles R. Griffiths 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).

  • Oscillatory circuit utilizing PTC resistor
    Patent number: 4320309
    Abstract: A control circuit for producing a repetitive closed-circuit, open-circuit condition between an electrical power source, such as a battery, and an electrical load comprises a positive temperature coefficient resistor in series with a relay coil. The PTC resistor is caused to alternate between a low resistance state and a high resistance state which permits energization and de-energization of the relay coil.
    Type: Grant
    Filed: December 31, 1979
    Date of Patent: March 16, 1982
    Assignee: GTE Products Corporation
    Inventors: Charles R. Griffiths, William G. Ferguson