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How Colour Changing LEDs Work

how_colour_changing_leds_work_1 A colour changing LED isn't one LED in a package but three LEDs along with a small computer to drive them. The LED is made up of red, green and blue LEDs each of which can be controlled by a microcontroller. Since the two legs on the LED that supply the power are connected to the microcontroller and not the LED elements a current limit resistor is not required.
how_colour_changing_leds_work_2 The microcontroller is able to turn each of the colours on or off, so if the red LED is turned on then the output from the colour changing LED is red. When the blue LED is turned on it is blue, if both the blue and red LEDs are turned on then the colour changing LED is a shade of purple (called magenta). Similarly combining red with green gives yellow and blue & green gives cyan.
how_colour_changing_leds_work_3 Although the colour changing LED uses the six colours mentioned above, it slowly changes from one to another. This is still done using the three basic red, green & blue elements. If the red LED is combined with the blue LED, but the blue LED is only driven at 50% of its normal brightness then a colour half way between red and magenta is generated.
how_colour_changing_leds_work_4 Whilst the red LED is left turned on, if the blue LED is slowly taken from 0% brightness to 100% brightness then the colour will gradually change from red to magenta.
how_colour_changing_leds_work_5 If a standard LED is turned on and off very quickly, say 100 times every second then as far as the human eye is concerned it looks like it is constantly on. If the amount of time the LED is on for is the same as the time it is off for then it will be on for 50% of the time and 50% of its full brightness.
how_colour_changing_leds_work_6 This same method can be done with the three LED elements inside the colour changing LED. This means it is possible to combine any amount of the red, green and blue to give the desired colour. Looking once again at the change from red to magenta, if the blue LED starts mainly turned off, goes to being on and off in even amounts and then to mainly being on then the the colour will change as required.

 

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15 thoughts on “How Colour Changing LEDs Work”

  • shonda blackmon July 30, 2014 at 3:57 pm

    what is the price ? I need product information on how it works and how is it controlled

    Reply
    • Rob Haywood August 11, 2014 at 2:24 pm

      Hi Shonda,

      The LED contains a micro controller which controls the LED. We sell two different types which you can find at www.kitronik.co.uk/3527 or www.kitronik.co.uk/3544.

      Reply
  • Andres July 12, 2016 at 10:02 am

    Is The LED Micro controllers phisical like any other controller or is it IN the LED. I would like to know for a DIY Mouse Project, But The LEDs in the mouse has changes colors automaticaly and i don't know how to change it or keep it on the same color
    Please Answer, Thank you.

    Reply
    • Mark Donnison July 12, 2016 at 10:41 am

      Hi Andres,

      There are colour changing LED's and there are RGB LED's, the colour changing LED's are pre-programmed to cycle through the colours in a pre determined way and this is controlled by a small on-board computer. With RGB LED's you can control which colour is active using PWM (Pulse width modulation). If you Google PWM you should get plenty of information that will help you.

      Reply
      • Gulmina April 2, 2017 at 10:51 am

        Can we turn these changable colour lights into one single colour????

        Reply
        • Mark Donnison April 3, 2017 at 11:57 am

          Hi, The colour changing lights are preprogrammed to cycle through the colours in a set way.

          Reply
          • Ben March 28, 2018 at 8:19 am

            I believe they are asking, can they be reprogrammed?

            Reply
  • John Potter July 27, 2017 at 11:56 am

    Having studied the inside of these LED's one can only be astonished at the complexity and work involved in their manufacture. To me it seems to be almost the crowning glory of modern electronics, such a lovely thing at such a low price. I have returned to electronics as a hobby after a 50 year break and what I have found is beyond my imagination. Thank you so much for this explanation.

    Reply
    • Mark Donnison July 27, 2017 at 5:11 pm

      You're welcome John! Best of luck with your rediscovery of electronics.

      Reply
  • Paul hickling August 10, 2017 at 2:25 pm

    What power supply would I need and apart from an on off switch would I need anything else

    Reply
    • Mark Donnison August 10, 2017 at 5:18 pm

      Hi Paul, We sell two different types which you can find at www.kitronik.co.uk/3527 or www.kitronik.co.uk/3544. If you look at the product page for www.kitronik.co.uk/3544, you will see the operating voltage and current requirements and that this LED does not require a current limit resistor if it is being powered in line with the values shown.

      Reply
  • Guy Manganese December 23, 2017 at 6:25 pm

    I have an existing color changing led which cycles in 7 seconds.
    I need the full cycle to be closer to 1 to 2 minutes long.
    Any suggestions?

    Reply
    • Mark Donnison January 2, 2018 at 9:51 am

      Hi Guy, we would need some more information in order to make a useful suggestion. We would need to know if it is the LED itself that is responsible for the timing of the cycle or if it controlled by the circuit that the LED is a part of.

      Reply
  • Darrell January 1, 2018 at 10:59 pm

    That is such a good explanation. Nice easy steps that build on the previous ones very concisely and makes it a joy to learn.

    Reply
  • Sue January 18, 2018 at 4:07 pm

    Does anyone else get annoyed by colour changing LEDs? - I want choose the colour/s - not cycle through a load of colours that clash with my decor until I get to the perfect colour for a fleeting moment!
    All the affordable decorative LED items cycle and very few facilitate colour selection. There's a huge market for you - right there!

    Reply
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