Switches & Leds

switches

• An electrical switch is any device used to interrupt the flow of electrons in a circuit. Switches are essentially binary devices: they are either completely on ("closed") or completely off ("open"). There are many different types of switches..

• Toggle switch• Push button switch• DIP switch• Relay switch

Toggle switch

• Toggle switches are actuated by a lever angled in one of two or more positions.

• The common light switch used in household wiring is an example of a toggle switch.

• Most toggle switches will come to rest in any of their lever positions, while others have an internal spring mechanism returning the lever to a certain normal position, allowing for what is called "momentary" operation.

Toggle switch

Push button switch• Pushbutton switches are two-position devices

actuated with a button that is pressed and released.

• Most pushbutton switches have an internal spring mechanism returning the button to its "out," or "un pressed," position, for momentary operation.

• Some pushbutton switches will latch alternately on or off with every push of the button. Other pushbutton switches will stay in their "in," or "pressed," position until the button is pulled back out.

Push button switch

DIP switch

• DIP(Dual-in line package) switch packages include several internal switches and are used extensively in printed circuit boards.

• Figure shows the schematic of a DIP switch with 4 and 8 internal SPST switches

DIP switch

Relay switch

• Relay is one of the most important electromechanical devices highly used in industrial applications specifically in automation.

• A relay is used for electronic to electrical interfacing i.e. it is used to switch on or off electrical circuits operating at high AC voltage using a low DC control voltage.

• A relay generally has two parts, a coil which operates at the rated DC voltage and a mechanically movable switch.

Relay switch

Basic LED Operations

To Turn an LED ON . . . • The ANODE must be at a higher

voltage potential (1.5v) than the CATHODE.

• The amount of current flowing through the LED will determine the brightness of the LED.

• The amount of current is controlled by a series resistor. (not shown)

To understand how a seven-segment display works, we must review how an LED works.

CATHODE (‒) (+) ANODE

← Current Flow

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Leds