The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 16, 1977
Filed:
Apr. 26, 1976
Applicant:
Inventor:
Laimons Freimanis, Chicago, IL (US);
Assignee:
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
179 / ;
Abstract
A telephone ringing circuit responds to both conventional high voltage 20Hz ringing signals and low voltage tone alerting signals. A conventional electromechanical ringer is connected across the telephone line and is responsive to high voltage 20Hz ringing signals. A high capacitance capacitor is charged by the dc voltage present on the telephone line and is discharged across the electromechanical ringer when a tone detector circuit connected across the line detects a tone alerting signal, thereby activating the electromechanical ringer.