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:
Feb. 07, 1989
Filed:
Apr. 10, 1986
Harald Schreiber, Salzkotten, DE;
Nixdorf Computer AG, Paderborn, DE;
Abstract
A circuit for remote supply of subscriber line terminals in telecommunication systems, especially suitable for employment in digital telecommunication systems, is described. The circuit comprises a supply circuit (10) at the beginning of the subscriber line (11), which circuit has a negative internal resistance operative when a preassigned supply amperage is exceeded. Between the subscriber line (1) and the terminal, a current converter cirucit (12) is provided, containing an energy reservoir (40) on the primary side and a switch-on circuit (41-44) operating in dependence upon its charge voltage for the switch pulses required for start-up. The operating current for the switch pulses is then delivered by a secondary winding (57) of the converter transmitter (27). A pulse width modulation of the switch pulses is effected, in addition to a control voltage derived from the secondary side of the converter transmitter (27), in the switch-on process, by a rising ramp-like direct current voltage preventing too violent a discharge of the condenser (40) at the input of the current converter (12). When switched on, the entire arrangement brings about a slow rise of the current on the subscriber line (11). Furthermore, the condenser meets the exaggerated energy demand upon start-up of the current converter (12) and compensates for fluctuations in energy demand during operation. The switch-on circuit (41-44) is kept switched on after the current converter (12) has been switched on by way of a direct current voltage derived form the secondary side, even if the input voltage drops below the switch-on circuit (41-44) switch threshold operative in the switched-off condition.