Coupler for microtelephone set

Abstract

Abstract An electronic coupler for a microtelephone set (14, 31) for the coupling of an amplifier (2) in a telephone line (33a) to an operating position in a telephonist-operated switchboard with automatic call distributor comprises a coupling circuit (1) with a field-effect transistor which is coupled in parallel across the amplifier (2) in such a manner that, when the supply current (E+) is coupled to the amplifier (2), it has great impedance against incoming A.C. signals in the audio frequency range, for example a ringing signal, whereby the line (29a, 29b) is connected to the telephone cartridge (14) via the amplifier (2), and also that the coupler (1) has low impedance against incoming A.C. signals when the supply current (E+) is not coupled to the amplifier (2), so that the line (29a, 29b) is coupled (37) around the amplifier (2) and connected directly to the telephone cartridge (14). What is thus achieved is that the telephonist merely has to await an acoustic signal via the telephone cartridge (14), which indicates that there is an incoming call to be answered or put through to an extension, after which the telephonist applies voltage to the operating position by activating a switch and answers the incoming call. The construction and the dimensions of the coupler are such that there is substantially achieved impedance matching between the telephone cartridge (14) and the line (29a, 29b) in both coupling situations.

Inventors

• 👤 Jorgen F. Elbaek

Bibliographic Details