Push switch

A push switch is a momentary or non-latching switch which causes a temporary change in the state of an electrical circuit only while the switch is physically actuated. An automatic mechanism (i.e. a spring) returns the switch to its default position immediately afterwards, restoring the initial circuit condition. There are two types:

• A push to make switch allows electricity to flow between its two contacts when held in. When the button is released, the circuit is broken. This type of switch is also known as a Normally Open (NO) Switch. (Examples: doorbell, computer case power switch, calculator buttons, individual keys on a keyboard)

File:Push-to-make switch electronic symbol.svg

Push-to-make switch electronic symbol

• A push to break switch does the opposite, i.e. when the button is not pressed, electricity can flow, but when it is pressed the circuit is broken. This type of switch is also known as a Normally Closed (NC) Switch. (Examples: Fridge Light Switch, Alarm Switches in Fail-Safe circuits)

File:Push-to-break switch electronic symbol.svg

Push-to-break switch electronic symbol

Many Push switches are designed to function as both push to make and push to break switches. For these switches, the wiring of the switch determines whether the switch functions as a push to make or as a push to break switch.

File:Push to Break.jpg

Commercially Available Push Switch - Wired up as a Push to Break Switch

File:Push Switch wired up as 'Push to Make'.jpg

Commercially Available Push Switch - Wired up as a Push to Make Switch