Telephone Collectors International
|First Posted Jun 24, 2013|
Last update Jun 15, 2014
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Telephone Collectors International is an organization of telephone collectors, hobbyists and historians who are helping to preserve the history of the telecommunications industry through the collection of telephones and telephone related material. Our collections represent all aspects of the industry; from the very first wooden prototypes that started the industry to the technological marvels that made the automatic telephone exchange possible.
If any of this interests you, we invite you to join our organization. Look around and see what we have to offer. Thanks for stopping by!
The system is based on switches that can select one of 500 positions in two motions. Rows of phosphor bronze bars the diameter of pencil lead are arranged in straight rows (called a "frame") in a semi arc running up and down the equipment rack. The contact wipers are mounted as such that they can rotate around 90 degrees one to 25 positions then extend in to a row of bars one to 20 positions, for a total of 500 positions.
Each office can grow to a maximum of 10,000 lines. Twenty frames are needed on the selector to access the connector switches needed to access 10,000 lines. That leaves five frames for trunks to other offices or 10,000 line groups in the same office. In figure one, a diagram of the selector frames is shown. The wipers are idled on the left side of the frames and they rotate clockwise, or to the right. The first five positions are for access to trunks and the remaining 20 are for the connectors. Each rectangle on the diagram represents a frame, the set of bars needed for 20 positions, which are wired to switches downstream from there. The wipers stop at the desired position, under the control of the register. The switch then extends the wipers into the frame and stops on the first idle position to seize a switch in the downstream rack.
Figure two shows a simple diagram for a 500 block of lines. There would be 20 of these for a 10,000 line office. For an office this size.....