Switches
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Switches are devices used to allow electric current to flow when closed, and when opened, they prevent current flow.  Common switch types include pushbutton, rocker, toggle, rotary coded DIP, DIP, rotary, keylock, slide, snap action, and reed.  A pushbutton switch is a mechanical switch defined by the method used to activate the switch. The activation method is typically in the form of a plunger that is pushed down to open or close the switch.  Rocker actuators are familiar in many on-off switches; they rock or pivot about the centerline, and include both maintained and momentary contact types.  In a toggle switch the toggle moves or swings to make or break the circuit; includes maintained contact and momentary contact types.  Rotary coded DIP switches are activated by means of a rotating shaft that can have several stop positions. For each position of the shaft (the input) the switch generates an output binary code.  A DIP (Dual In-line Package) switch is an electronic package (circuit board) consisting of a series of tiny switches. Typically used in the configuration of computers and computer peripherals (for example, circuit boards, modems etc.).  Rotary switches move in a circle, and can stop in several positions along its range.  Keylock switches have key as the means of activation. The key is turned in a circle, and can stop in several positions in its range.  In a slide switch a slider moves linearly (slides) from position to position.  A snap action switch is a mechanical switch that produces a very rapid transfer of contacts from one position to another. They are useful in situations that require a fast opening or closing of a circuit, such as a mouse button or appliance setting.  Reed switches are magnetically activated switches. They are typically manufactured with two ferromagnetic reeds (contact blades), which are sealed in a glass capsule. In the presence of a magnet, the blades (contacts) close.

Pole and throw configurations for switches can be single pole single throw (SPST), single pole double throw (SPDT), double pole single throw (DPST), or double pole double throw (DPDT).  SPST is a switch that makes or breaks the connection of a single conductor in a single branch circuit. This switch typically has two terminals. It is commonly referred to as a "Single-Pole" Switch.  SPDT is a switch that makes or breaks the connection of a single conductor with either of two other single conductors. This switch typically has 3 terminals, and is commonly used in pairs and called a "Three-Way" switch.  DPST is a switch that makes or breaks the connection of two circuit conductors in a single branch circuit. This switch typically has four terminals.  DPDT is a switch that makes or breaks the connection of two conductors to two separate circuits. This switch typically has six terminals and is available in both momentary and maintained contact versions.  The switch function can be maintained contact, momentary contact, or alternating contact.  In a maintained contact switch an actuator stays in thrown position. This includes on-off, but it also includes Three-Position - (Center-off) and Three Position - (No Center-off) switches where the switch remains in its actuated position.  In a momentary contact switch the switch must be held in position; it reverts to normal position when actuating force is removed.  Alternating action such as push on, push off characterizes an alternating contact.  A normally open (NO) switch has contacts that are open or disconnected in their unactuated (normal) position.  A normally closed (NC) switch has contacts that are closed or connected in their unactuated (normal) position.

Important electrical switch specifications to consider when searching for switches include maximum current rating, maximum AC voltage rating, maximum DC voltage rating, and maximum power rating.  Other important parameters to consider when searching for switches include the terminal type, construction materials, common features, and environmental conditions.
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