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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.
EMS-1 (The ITEC Electronic Modular Switch is an electronic direct control switching system. The modules are combined to form a complete switch or any of the modules can be added to your present Step-by-Step Systems.) EMS-2 (The EMS-2 RURAL SWITCH is a stored program control analog switch designed to be cost-effective in small exchanges.
Lipartito, Kenneth. “When Women Were Switches: Technology, Work, and Gender in the Telephone Industry, 1890-1920.” American Historical Review 99#4 (1994) pp. 1074–111. ONLINE; Mueller, Milton. "The switchboard problem: scale, signaling, and organization in manual telephone switching, 1877-1897." Technology and Culture 30.3 (1989): 534 ...
Manual service is telephone service in which a human telephone operator routes calls as instructed by a subscriber with a telephone set that does not have a dial. Dial service is when an exchange routes calls by interpreting subscriber-dialed digits. A telephone switch is the switching equipment of an exchange.
An automotive wiring diagram, showing useful information such as crimp connection locations and wire colors. These details may not be so easily found on a more schematic drawing. A wiring diagram is a simplified conventional pictorial representation of an electrical circuit. It shows the components of the circuit as simplified shapes, and the ...
The U.S. National Electrical Code (NEC) defines a switchboard as "a large single panel, frame, or assembly of panels on which are mounted, on the face, back, or both, switches, over-current and other protective devices, buses, and usually instruments". [2]
The switches may be arranged so that they are in the same orientation for off, and contrasting orientations for on. [1] A "4-way" (intermediate) switch is a purpose built double pole, double throw (DPDT) switch, internally wired in manufacture to reverse the connections between the input and output and having only four external terminals. This ...
Yellow NEMA 5-15 extension cord NEMA-1 extension cord, common in the United States Extension cord reel (Germany). An extension cord (US), extension cable, power extender, drop cord, or extension lead (UK) is a length of flexible electrical power cable (flex) with a plug on one end and one or more sockets on the other end (usually of the same type as the plug).