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Light Emitting Diode

From DT Online

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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
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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).


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
Spiratronics Batten Lampholder 2 Pack + 2x 3V Bulbs Spiratronics E10 MES Lampholder 3 Pack + 3x 3V Bulbs TOOGOO(R) 20pcs 10mm Red Emitting Diode Light Bright LED sourcingmap 50 Pcs 2 Terminal 10mm Round Head Green LED Emitting Diodes Lamp 5mm Assorted Clear LED Diode with Resistors 8 Colors, Pack of 80 Newest 10pcs Common Cathode 10 pin 1 Bit 0.5 20X4 Character LCD Module Display Blue Backlight for Arduino
Batten Lampholder + 3V Bulbs (x2) E10 MES Lampholder + 3V Bulbs (x3) 20pcs 10mm Red Bright LED 50pcs 2 Terminal 10mm Round Head Green 5mm Assorted Clear LED with Resistors 8 Colors, Pack of 80 10pcs Common Cathode 10 pin 1 Bit 0.5" LED Display 20X4 Character LCD Module Display Blue Backlight for Arduino