Created on: 30 July 2012
The schematic symbols for two different types of switches are shown below:
The switch symbol on the left represents a switch that when switched on, will stay on and when switched off will stay off. This switch is a "single pole single throw" switch.
The switch on the right represents a switch that will only be closed when pushed. It will switch off when released and never latch closed. This is known as a momentary switch.
In schematic diagrams, the reference designator for a switch will typically start with S or SW as shown.
The switches on the left of the photo below are momentary tactile switches. The switch immediately to the right of these switches is a bigger momentary switch with a cap. The switch to the right of this is a push button single pole switch. Next is a toggle switch and finally a key switch.