Switch Types

Rocker switch

Toggle switch

Push button switch

Switches come in many different forms and with different switch contact arrangements. Three of the most common types of switch are shown above, these particular ones all have SPST contacts.

Push-to-make switches have two contacts that are joined together when the button is pressed. The switch shown has a momentry action which means that the switch is closed only when the button is depressed. Latched types are available that latch in a position until the button is depressed again.

The contacts of a push-to-make switch are normally closed. When the button is pressed the contacts are seperated and the switch opens.

SPST stands for Single-pole-single-throw. The example image shown is a toggle switch, depending on the position of the "toggle" the switch is either open or closed.

SPDT stands for single-pole-double-throw. The centre contact is joined with either of the other two contacts depending on the position of the switch. The type of switch shown is a toggle switch although many other switches exist with this configuration.

DPDT stands for double-pole-double-throw. It consists of two SPST switches which are joined together internally so both sets of switches are opperated by the same mechanism.

Reed switches consist of two metal contacts enclosed in a sealed glass envelope. The contacts are normally open but when a magnet is brought close the contacts are attracted to the magnet and the switch is clossed. Once the magnet is removed the switch contacts open once more. They are commonly used in security systems to determine if a door (which has a magnet attached) is open.

A microswitch is a type of switch where very little physical pressure is required to open and close the switch. They are used in console joysticks and pads and in equipment such as 3D printers to detect when the head is in a particular position. They are also used in mechanical and electrical equipment to disconnect the electricity supply when an access panel or door is opened. The images shows a SPST type.

Traditionally tilt switches consist of two metal contacts and a pool of mercury enclosed within a glass envelope. Tilting the switch causes the mercury to move and either make or break the circuit. Due to the toxicity of mercury however, modern tilt switches contain a solid metal ball instead.

A multiposition, unsuprisingly, has a single pole and multiple throws. In other words the central contact can be made to connect with any of the contacts on the right depending on the position of the switch knob.