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LEDs changing colors

Discussion in 'LEDs and Optoelectronics' started by cb77305, Apr 4, 2016.

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  1. cb77305

    cb77305

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    Aug 11, 2011
    I have a set of those solar-powered LED garden sticks that charge by day and light at dusk. Upon inspection there are but two wires going from the circuit to the LED. What causes that LED to cycle between red, green, and blue? There's some king of 4-connector chip on the tiny circuit board with writing way to small for me to see. Does anyone have some ideas on what the circuitry might be?
     
  2. Gryd3

    Gryd3

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    Jun 25, 2014
    If there are only two wires to the LED, then the cycling between colors is being caused by a very small internal chip embedded IN the LED casing. It's not uncommon to see, they are usually voltage driven instead of current driven like standard LED due to the internal circuitry.
    I had a bunch that cycled green/red as basic Xmas lights, and my son has a bath-toy that does all 3 primary colors. (It has 6 LEDs in it... and they all end up out of sync with each other if you run it for a while because the internal clock on each LED die is slightly different)
     
  3. cb77305

    cb77305

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    0
    Aug 11, 2011
    I had no idea. Thanks for that quick reply. I bought a plug-in night light for the bathroom that does the same thing - cycles between four or five colors. Maybe it seems like more because the one color is still present when the next starts coming up. Does that small chip drive several LEDs or just the one?
     
  4. Gryd3

    Gryd3

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    Jun 25, 2014
    The small chip is embedded inside the LED casing... usually clear casing.
    It technically controls more than one 'LED'... but considering the color changing LEDs have 2 or 3 colors, they are typically 2-3 LED dies embedded all together with the same chip... so this built-in chip cannot control any physically separate LEDs.
    If there is more than one physical LED, then they have simple built-in circuits to 'fade' in and out or electronics inside the device control each LED.
    If you power off the device and look very carefully into the business end of the LED, you may see 3 or more tony little squares. 2-3 for colors, and the 'controller' may or may not be visible. That little square is what makes the light... the rest of the 'LED' is simply metal legs to work with and a clear casing.
     
  5. cjdelphi

    cjdelphi

    1,096
    104
    Oct 26, 2011
    That 4 pin chip is the 5252f ? (From memory) it steps the voltage up from 1ish volts to 3-4v to drive the rainbow 2 pin LED
     
    Gryd3 likes this.
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