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Project Notes

#243 Switches

Notes on miscellaneous mechanical switches used in electrical circuits.



Switches are the most basic of “input” devices for electrical systems.

Thorough coverage of the variety of switches can be found in Chapter 6 of Charles Platt’s excellent Encyclopedia of Electronic Components Volume 1, and also (coincidentally) Chapter 6 of John M. Hughes’ Practical Electronics: Components and Techniques.

Pole and Throw Terminology

The terms pole and throw are also used to describe switch contact variations.

The number of “poles” is the number of electrically separate switches which are controlled by a single physical actuator. For example, a “2-pole” switch has two separate, parallel sets of contacts that open and close in unison via the same mechanism.

The number of “throws” is the number of separate wiring path choices other than “open” that the switch can adopt for each pole. A single-throw switch has one pair of contacts that can either be closed or open. A double-throw switch has a contact that can be connected to either of two other contacts, a triple-throw has a contact which can be connected to one of three other contacts, etc


Types of Switches

  • Toggle switch - DPDT
  • Rocker
  • Slide
  • Rotary
  • Pushbutton - typically momentary action, but sometimes locking on/off
  • Snap-action - typically used as sensors

Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.