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Switching Devices 

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This section is a review of the many switching devices invented for use in telephone exchanges. See the Appendix below for coverage on "The Essential Electrical Switch" and a tutorial video on electromechanical switching for exchanges. 
Primarily, the coverage here is focused on switch mechanics; how it works. A given switch is used multiple times in the fabric that creates the talking path end-to-end.  The switches are designed to route the "talking path", usually 2 or 3 wires per connection. One exception is is the "Sequence+" switch in the diagram below. Explore it to see its function. 

Don't confuse the switch name with it's sometimes namesake exchange. For example a crossbar switch is used in the Crossbar exchange. To appreciate how a given switch integrates into an exchange, see the master diagram on the Exchange Anatomy page.

The switch names in the diagram/menu are categorized based on what movements they use to make a connection; either linear motion, radial motion, both, or some other ways. So, most switches have either one or two degrees of freedom for moving its connecting arms to make a circuit.

This is not an exhaustive list. However, the ones here are either important because of their proven success or pure ingenuity. The hierarchy implies at least some inheritance nature. For example, the devices below "First Strowger" are influenced by this design. Also, the ordering, top to bottom, is by date, first to last (approximately). 

Select the (i) near a switch name to explore its nature. The switch coverage includes commentary, images and often one or more videos.  Again, the scope is on individual switch mechanics and not about how calls are made in an exchange. 

Master diagram showing links to 15 telephone switch types - ordered by movement type

This section is for mobile device navigation and has the same choices as the graphical navigation for desktop browsers. The switch coverages include commentary, images and often one or more videos.  The scope is on individual switch mechanics and not about how calls are made in an exchange. 

Bell System Panel

Solo Rotar
Bell System 7A Rotary

3D images of switches

Linear + Rotary:
First Strowger
Keith's Zither
Keith's Strowger
Ericsson 500 
Keith's Plunger line switch
Ericsson XY

Other methods:
Sequence switch

The Essential Switch

Aside from a single piece of wire, the electrical switch is the most fundamental component in any electrical system. From the humble light switch, to high voltage utility switching, to computers and AI, switching is paramount for their functionality.

The video (Part 1) below explores various types of electrical switches, brought to life through vivid illustrations and animations. The purpose is to appreciate the switch and the role it plays across the domains of electrical and electronic technologies. The focus is generic and not confined to telephone topics. 

The Part 2 video below focuses on electromechanical telephone exchange switching. It reviews the 7 classes of talking path switches as used in exchanges worldwide for over 90 years. In the main body of this article, above, you can access individual explainers on 16 switch types. 

(When playing the video, it may not start at beginning. If so, please rewind to the start position.)
Title: Electromechanical switching methods for telephone exchanges Part 2

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