Telephone switching circuit controlling connection between telephone sets - having two anti parallel thyristor type semiconductors for each set with gate electrodes connected via resistor

摘要

The telephone switching circuit is for use with two or more terminals connected in parallel to a common subscriber line (AL1,AL2) in a telephone system. The terminals (1,2) have restricted access to the telephone system in that only one at a time can have telephone connection within the system. The telephone switching circuit (11) has two anti-parallel connected semiconductor elements (3,5) of thyristor character for each terminal, inserted in one line branch (11A) between the terminal and the line. The output electrodes (3A,5A) of the semiconductors lie in series in the line branch (11A). Gate electrodes (3C,5C) of the semiconductors are connected to each other through a resistor (4). Pref., an additional resistor (6,7) is connected between the input electrodes (3B,5B) and the gate electrode of each semiconductor element.