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:
Jul. 10, 1990
Filed:
Apr. 20, 1989
Thomas McCartney, Bannockburn, IL (US);
Melvin A Lace, Prospect Heights, IL (US);
Oneac Corporation, Libertyville, IL (US);
Abstract
Overvoltage protection arrangements are provided for a pair of telephone lines effective for suppressing noise and transient voltage signals occurring above data and voice signals carried on the telephone lines and that avoids current flow between the telephone lines responsive to common mode voltage signals on the lines so that audible hum is avoided. The overvoltage protection arrangements include first voltage clamping circuitry for clamping voltage signals on the lines at a first predetermined voltage potential and second voltage clamping and filter circuitry for clamping voltage signals on the lines at a second predetermined voltage potential and for filtering noise and transient signals from the voltage signals only when the voltage signals exceed the second predetermined voltage potential. The second voltage clamping circuitry substantially avoids current flow between the lines responsive to common mode voltage signals on the lines.