These are some terminologies associated with switches.All switches, regardless of how they look or the size or what part of the body is used for control, operate in the same manner.
A switch is a mechanical device used to open and close a circuit. Opening a circuit (usually turns a device OFF) is achieved by breaking a connection in the circuit. This stops current flow. Closing the circuit (usually turns a device ON) allows the current to flow again.
- Normally Open (N.O.)
- Without activating the switch, the contact is open.
- Normally Closed (N.C.)
- Without activating the switch, the contact is closed.
- Single Pole Single Throw (SPST)
- Activating the switch opens/closes one circuit.
- Single Pole Double Throw (SPDT)
- Activating the switch opens/closes the connection of one circuit to one of two.
- Double Pole Single Throw (DPST)
- Activating the switch opens/closes the connection of two circuits to one.
- Double Pole Double Throw (DPDT)
- Activating the switch opens/closes two circuits.
- Momentary
- The switch is closed/open only when the switch is activated.
- Latch
- The switch remains closed/open until the switch is activated again.
- Feedback
- The switch indicates that it has been activated.
For example: visual (light), audio (click).
- Rating
- The maximum voltage and/or current that the switch can handle without damage.