TELECOMMUNICATION CONNECTING CIRCUIT

摘要

A circuit arrangement for connecting telegraph and data subscribers to the four-wire interface of a switching system over two-wire single-current lines, comprising an electronically adjustable resistor for setting the subscriber line current, an RC flattening network coupled to the output of the two-wire line and an electronic circuit means connected to the output of said RC network for providing sharp edged pulses to the transmitting lines. The polarity of the two-wire subscriber line for permitting sending from the interface to the subscriber is determined by a switching transistor (T7) operating as a make/break contact. A threshold device provides switching signals to fix the state of the switching transistor. An electronic current-limiting circuit is normally connected in the two-wire subscriber circuit to prevent reflections therein; a second electronic current-limiting device may be employed to prevent short circuits and extraneous voltages.