Introduction

Till now you might be thinking that there is only one type of LEDs that generate only one type of color, i.e., anyone of the following, RED, GREEN, BLUE, etc. And yes there is one more kind of LED, that generate no color, but still works, & have effect in the applications in which it is used, that LED we known as Infra Red LED.

But this is not the end of the Light Emitting Semiconductor device family, there is group ( of LED ) that are capable of generating various color though they are of same size, same number pins, or even various things that are similar.

LED Family- Includes, single color, Bi-Color & RGB LEDs

Single Colored LEDs ( RGY ) Multi-Color LEDs

Multicolored LED Pattern A Multi-Color LED is actually capable of generating many color ( more that one ), within itself. And that's the main things that attracts different electronics system designers for using it as they want their system to occupy as less space as possible. For that purpose they are best, as One RGB LED which is actually capable of generating Red, Green & Blue including to them 3! (factorial) i.e, 6 colors are possible like in addition to RGB, they are cyan, magenta & yellow. This property is well utilized by the motherboard manufacturer, to show the power indication, RED means lower power than the recommended rating, green means ambient power etc. So they compacted the space requirements.



Bi-Color LEDs:(Actually Capable Of Generating 3 Colors)

So lets see the below equivalent circuit of a bicolor LED (Common Anode one) & try to understand a bit about it...

Bi-Color LED General Equivalent Circuit Diagram A Multi-Color LED is actually capable of generating many color ( more that one ), within itself. And that's the main things that attracts different electronics system designers for using it as they want their system to occupy as less space as possible. For that purpose they are best, as One RGB LED which is actually capable of generating Red, Green & Blue including to them 3! (factorial) i.e, 6 colors are possible like in addition to RGB, they are cyan, magenta & yellow. This property is well utilized by the motherboard manufacturer, to show the power indication, RED means lower power than the recommended rating, green means ambient power etc. So they compacted the space requirements.So lets see the below equivalent circuit of a bicolor LED (Common Anode one) & try to understand a bit about it...

Bi Color LED Schematic

From the above two pictures we can say that the there are three pins of it, instead of the common two pins, the common pin ( The middle pin ) which will be attributing it to be a common Anode or Common Cathode will help us decide that wether a +5V power supply has to added or GND has to be applied(if its common anode then apply GND to the middle/common pin other vise viceversa). The First pin of the above LED is attributed to generate the Green color & the third pin will generate Red color if a positive voltage supply is given to it, in case of common anode or GND to it in case of Common Cathode. What if we make the 1st & the 3rd terminal either +5V or GND, well in that case it will simply either switch off ( In reverse biased condition) or both the color will be producing simultaneously resulting in a different 3rd color.

A Bi-Color LED

FYL-3015xx Bicolor LED Schematic

Example of one of the application of it :

Bipolar LED Driver

In the above circuit the 555 timer circuit will be producing the square wave, in the negative cycle it will be compelling the LED to generate RED led & green one in positive cycle. So there will be a tick-tock between RED & Green color in that LED.

RGB LEDs or Tri-Color LEDs

Equivalent Circuit Of RGB LED

Different Color Combination Possible Analogically & Digitally

RGB LEDs Producing different color in one of the application

Another Type Of RGB LED That Are Available in the Market Is:

RGB LED Pin Configuration (source : pjrc .com)

Some Application Circuits:

RGB LED COLOR FLASHER USING ARDUINO

Project Schematic Generated by Fritzing Software(we will be posting tutorial on the soon! So Stay Tuned)

mood cude

ELECTRIC MOOD CUBE

LED Mood Cube

They are also of two types, similar to the Bi-Color LEDs, i.e., common anode & common cathode. They are able to generate Red, Green & Blue, in addition to them the color possible by combining them. Actually Controlling the RGB LED digitally 7 colors are achievable:Keep the common anode at the ground level and apply voltage to other terminals according the color you want to obtain, you will different colors, and do experiment with it by applying positive voltages to other terminals.Longest lead (pin 2) is Cathode (-)Pin 1 -( emits light of 650nm) Green - Short Lead (same length as Green)Pin 2 - Negative/Cathode Longest leadPin 3 - CB (emits light of 470nm) - Blue - 2nd longest leadPin 4 - BG (emits light of 520nm) - Red - Short lead (same length as red)Pin 2 (longest) is the common cathode to all 3 colors.One more application that we found over the internet is another wonderful circuit, and can be implemented by any micro controller having much pins to support it, that is the!!