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Each connection to a telephone set required six wires from the key system: [5] One pair (two wires) carried the talk circuit (tip and ring), one pair carried control information, known as A-Leads, for that line, designated A and A1, and the third pair carried current to a lamp for the specific line key position on the telephone set (L and LG).
A third pair consists of white tip coding and blue ring coding. For larger cable assemblies more complex schemes, such as the 25-pair color code , are used. Some telephone technicians used mnemonic phrases, such as red-right-ring-rear , or ring-right-red-rough , to remember that the red wire connects to the right-side post in the wall jack and ...
The wire pairs are referenced directly by their color combination, or by the pair number. For example, pair 9 is also called the red-brown pair. In technical tabulations, the colors are often suitably abbreviated. Violet is the standard name in the telecommunications and electronics industry, but it is sometimes referred to as purple.
Signal operating instructions (SOI) or Communications-Electronics Operation Instructions (CEOI) are U.S. military terms for a type of combat order issued for the technical control and coordination of communications within a command. [1]
PBX switchboard, 1975. A telephone switchboard is a device used to connect circuits of telephones to establish telephone calls between users or other switchboards. The switchboard is an essential component of a manual telephone exchange, and is operated by switchboard operators who use electrical cords or switches to establish the connections.
The 25-pair standard non-split 66 block contains 50 rows; each row has two (E) or four (M) or six (A) & (B) columns of clips that are electrically bonded. The 25-pair split 50 66 block is the industry standard for easy termination of voice cabling, and is a standard network termination by telephone companies—generally on commercial properties.
An early example of shielded twisted-pair was IBM STP-A, which is a two-pair 150 ohm S/FTP cable defined in 1985 by the IBM Cabling System specifications, and used with Token Ring or FDDI networks. [7] [11]
Digital Addressable Lighting Interface (DALI) is a trademark for network-based products that control lighting.The underlying technology was established by a consortium of lighting equipment manufacturers as a successor for 1-10 V/ 0–10 V lighting control systems, and as an open standard alternative to several proprietary protocols.