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Difference between revisions of "Light Emitting Diode"

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=====Features and Applications=====
 
=====Features and Applications=====
  
LEDs are easily damaged by excess current therefore it is normal to connect the LED to the supply via a series current limiting '''[[Resistor|resistor]]'''. The value of this resistor is not critical but is usually within the range 100 - 330R.
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LEDs are easily damaged by excess current therefore it is normal to connect the LED to the supply via a series current limiting '''[[Resistor]]'''. The value of this resistor is not critical but is usually within the range 100 - 330R.
  
  
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=====LEDs in a Transistor Circuit=====
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[[File:LightEmittingDiode.png|200px|right]]
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The most common LEDs are 5mm diameter. They glow ''(commonly red)'' when current flows through them ''(current can only flow if the anode is more positive than the cathode)''.
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The LED has a forward voltage of 2V, i.e 2 Volts is dropped across the LED when it is in operation. It requires a maximum current of 30mA. The '''[[Resistor]]''' in the circuit is included to limit the current to around this value.
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{{Bulbs & LEDs Buyers Guide}}
 
{{Bulbs & LEDs Buyers Guide}}
  

Latest revision as of 18:16, 2 November 2016

LEDs.png


Description

Light Emitting Diodes (LED) come in different colours, shapes, sizes and brightness. The more common colours being red, green and yellow.


They are also available in bi-colour and tri-colour versions. Round ones come in 3, 5 and 8mm sizes. There are also rectangular, square and bar types.


Flashing types are available and seven segment displays are made of a number of LEDs in a particular pattern.


Features and Applications

LEDs are easily damaged by excess current therefore it is normal to connect the LED to the supply via a series current limiting Resistor. The value of this resistor is not critical but is usually within the range 100 - 330R.


Polarity must be observed when connecting LEDs (it should be noted that LEDs are damaged by reverse biased voltages larger than about 6 volts).


The Anode is connected to the positive supply via the limiting resistor. The Cathode is connected to the negative supply.


LEDs in a Transistor Circuit
LightEmittingDiode.png

The most common LEDs are 5mm diameter. They glow (commonly red) when current flows through them (current can only flow if the anode is more positive than the cathode).


The LED has a forward voltage of 2V, i.e 2 Volts is dropped across the LED when it is in operation. It requires a maximum current of 30mA. The Resistor in the circuit is included to limit the current to around this value.


DT Online Buyers' Guide
Batten Lampholder + 3V Bulbs E10 MES Lampholder 10mm Red Bright LED 10mm Green Bright LED 5mm Assorted Clear LED with Resistors Common Cathode 10 pin 1 Bit 0.5 20X4 Character LCD Module Display Blue Backlight for Arduino
Batten Lampholder + 3V Bulbs E10 MES Lampholder 10mm Red Bright LED 10mm Green Bright LED 5mm Assorted Clear LED with Resistors Common Cathode 10 pin 1 Bit 0.5" LED Display 20X4 Character LCD Module Display Blue Backlight for Arduino