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:
Jan. 12, 1982
Filed:
Jan. 17, 1980
Joseph H Mehaffey, Atlanta, GA (US);
Solid State Systems, Inc., Marietta, GA (US);
Abstract
An interface for connecting a PBX line (18) to a central office trunk (15) and for providing a supervisory signal (28) and accepting PBX hook switch and dial pulse inputs (30), being readily adaptable to ground start trunks and loop start trunks. A pair of transistor switches (55, 56) sharing a common base drive (57) is biased by a differential bias means (59, 60, 61) to operate a ground start isolated switch (32, 35) and an isolated loop closing switch (36, 37). The supervisory signal is controlled by a comparator (45) which senses grounding of central office tip (16) to establish the supervisory signal and is subsequently responsive only to the presence of current in the central office loop detected by a relay (65) buried in a coupling transformer.