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:
Jun. 21, 1977
Filed:
Feb. 02, 1976
Paul Shylo, Arlington Heights, IL (US);
Cook Electric Company, Morton Grove, IL (US);
Abstract
A ringer isolator is used in conjunction with a pair of telephone lines to isolate ringer coils coupled to one of the telephone lines from a reference terminal except when a ringer signal is applied to the telephone lines. The ringer isolator includes an isolator such as a neon lamp/photo resistor coupler or a transformer partly coupled between the telephone lines and partly coupled to a thyristor such as a silicon controlled rectifier or a triac. The thyristor is coupled in series relationship between the ringer coils and the reference terminal. Normally, the thyristor is maintained nonconductive so that the ringer coils cannot be energized by potentials on the telephone lines. In response to the ringer signal being applied to the telephone lines, the isolator enables the thyristor to be rendered conductive so that the ringer coils are energized by the ringer signal.