Types of Switches Used in Electronics Projects

By Earl Boysen, Nancy C. Muir

Part of Electronics Projects For Dummies Cheat Sheet

A switch seems simple enough: You flick it one way to go on and the other way to go off. With an electronic project however, understanding how different types of switches operate helps you decide which type to use where. The following lists describe the two states a switch can be in and what happens behind each type of switch.

The two states of a switch:

  • Open: A switch is in an open state when there is no electrical connection. When a switch is open, there is a very high resistance between a wire coming into the switch and the wire going out of the switch.

  • Closed: A switch is closed when there is an electrical connection. When a switch is closed, there is very low resistance between a wire coming into a switch and the wire coming out of the switch.

Switches are referred to by the method used to change their state open to closed:

  • Toggle switch: This switch gets its name from the fact that you flip a lever to turn it on and flip it back to turn it off.

  • Pushbutton on/off switch: Every time you push this button, the switch changes from on to off or vice versa.

  • Momentary pushbutton switch: Pushing this switch is what changes its state, but only for the moment! These are also classified by whether they are normally open or normally closed. For example, a momentary normally open switch is closed only while you hold the pushbutton down. When you release the button, it goes back to its normal open state.

  • Tactile switch: This is a type of momentary pushbutton switch. Tactile switches are rated by the amount of force needed to push the button and are often flat so that they can be easily inserted within a surface without protruding.

  • Slide switch: Logically, this switch operates when you slide a knob to change it from on to off or vice-versa.

  • Relays: These switches are operated by a voltage rather than by pushing a switch. This makes them very useful for turning on or off a component, such as a light or motor, through a remote control or by voltage generated by a sensor.