GB547836A - Calling line identification circuit - Google Patents

Abstract

547,836. Transformers. STANDARD TELEPHONES & CABLES, Ltd. June 27, 1941, No. 8107. Convention date, July 3, 1940. [Class 38 (ii)] [Also in Group XXXIX] In systems in which a tone is applied to the metering wire of a connection to enable a calling subscriber's line to be identified, the identifying arrangements for 10,000 lines comprise two groups of 100 transformers each. Each transformer in the first group corresponds to a particular combination of the first two digits of the line numbers and has 100 primary windings, one connected to each of the lines having that combination. The transformers of the second group are correspondingly arranged as regards the tens and units digits. Each transformer has two secondary windings. The first winding of each of the transformers with the same thousands digit is connected to a common circuit such as M1, and the second winding of each transformer with the same hundreds digit is connected to a common circuit C1, C2 &c. Similar arrangements are made in the transformers of the second group as regards the tens and units digits. It follows that when a tone is applied to a particular subscriber's line, tone currents will be induced in the four common circuits corresponding to his number. To enable the number to be registered or recorded, the thousands, hundreds, tens and units circuits are connected up in turn to ten amplifier detectors by a relay distributer, Fig. 2 (not shown). Specifications 484,568 and 484,647, [both in Group XXXIX], are referred to. Transformers.-The 100 primary windings are applied to a transformer after it has been assembled and mounted in the form of a standard 100 conductor switchboard cable. The magnetic circuit is provided with a groove to accommodate such a cable with its protective covering removed and when the cable has been laid in place the magnetic circuit is completed.