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:
Apr. 25, 1978
Filed:
Feb. 16, 1977
Hans Rudolf Schindler, Langnau, CH;
Peter Vettiger, Thalwil, CH;
International Business Machines Corporation, Armonk, NY (US);
Abstract
This invention comprises a telephone hybrid circuit having two opto-coupler arrangements for transferring voice signals from the two-wire line to a port of the switching system on one hand and from a port of the switching system to the two-wire line on the other hand. In addition, a pair of feeder circuits in the form of current sources comprising active elements are provided for feeding a constant positive direct current to one wire of the two-wire line and a negative direct current of equal magnitude to the other wire of the two-wire line. Each of the current sources includes control circuitry for maintaining a constant ratio between the current furnished by the current source and a control current common to both current sources. A control current path is connected to the output of one of the opto-coupler arrangements for generating a common control current in response to a dc signal and a superimposed voice signal received from a port of the switching system. The other opto-coupler arrangement couples the signals from the two-wire line to a port of the switching system.