Basic Electronics for Beginners in 20 Steps

Step 13: Switches

A switch is a mechanical device that either opens or closes a circuit. When you activate it, the switch either completes the circuit (closes) or breaks the connection (opens), depending on its type.

• Normally Open (N.O.) switches close the circuit when activated.

• Normally Closed (N.C.) switches open the circuit when activated.

Some switches are more complex and can open one connection while closing another. A switch like this is called a Single-Pole Double-Throw (SPDT) switch.

If you combine two SPDT switches into one, you get a Double-Pole Double-Throw (DPDT) switch. This type of switch can break two separate circuits and open two other circuits each time it’s activated.