MPN

Switches

Switches are electromechanical components used to control the flow of electricity in both electrical and electronic circuits. They allow users to turn circuits on or off or switch between different operational states.

Most switches are binary devices that operate by opening or closing a set of internal contacts. When the contacts are closed, current flows through the circuit (ON state); when the contacts are open, the circuit is broken and current cannot flow (OFF state).

Switches typically feature terminals that connect to wires or PCB traces, and an internal mechanism that actuates the contacts based on user input — such as a button press, toggle, or rotary motion.

What are Poles and Throws?

The number of circuits controlled by a switch is referred to as "poles". The number of positions that the switch can adopt is called "throws". The combinations of these are:

SPST (Single Pole Single Throw)
SPDT (Single Pole Double Throw)
DPST (Double Pole Single Throw)
DPDT (Double Pole Double Throw)

What types of switches are there?

The type of switch you require depends on the connections you wish to make within your circuit. Switches are often grouped by the way they are operated, for example, rocker switches that rock side to side. Alternatively, they are classified by their application, for example, keypad switches are used with keypads. Here are some examples of switch types:

Switches By Actuation Method:

Push Button Switches - Activated by pressing a button, commonly used for emergency stop buttons
Toggle Switches - Switched via a lever or toggle.
Rocker Switches - Rock side-to-side to open/close a circuit.
Rotary Switches - Turned to select different circuit paths.
Foot Switches - Operated by foot pressure.
Key Switches - Require a physical key for actuation.

Switches By Sensing or Input Technology:

Hall Effect Switches - Non-contact switches using magnetic fields.
Piezo Switches - Activated by pressure using piezoelectric elements.
Microswitches (Snap Action) - Require minimal force to actuate rapidly

Switches By Application/Form Factor:

DIP & SIP Switches - Compact switches for PCBs and logic control.
Keypad & Keyboard Switches- Integrated into user input devices.
Detector Switches - Used for sensing object presence or position.
Joystick Switches - Multi-directional control for equipment and consoles.

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