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:
Mar. 24, 1987
Filed:
Jul. 26, 1985
Ely S Zofan, Reynoldsburg, OH (US);
Floyd Bell Associates, Inc., Columbus, OH (US);
Abstract
A frequency selective ringer circuit which utilizes a constant current source in conjunction with an array of resistors and switches for developing a frequency selective window with which to detect an incoming frequency at the tip and ring inputs of a telephone system. The incoming frequency is doubled and converted to a d.c. level which is utilized as the converted level which is evaluated by the circuit. Where the converted voltage level falls within the established window, a drive circuit is energized for actuating a transducer such as a piezoelectric crystal or loudspeaker. Frequency selection is made by the simple expedient of closing one of a plurality of SPST switches. The circuit also may include a circuit for automatically deactivating the mechanical bell of an existing telephone set without the removal thereof.