Smallest RGB LED Controller

Discussion in 'The Projects Forum' started by don.key, Oct 9, 2012.

  1. don.key

    Thread Starter New Member

    Oct 9, 2012
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    Hi Folks,

    I need to integrate 1-3 miniature multicolor RGB LEDs into very small space and need them to do run some automated patterns, a slow Rainbow color change loop at least. All at the same time, no need to drive each LED individually. It should be as small as possible and run off single CR2032 cell.

    Is there such product or blueprint for a controller board out there?

    Thanks!

    Don
     
  2. MMcLaren

    Well-Known Member

    Feb 14, 2010
    759
    116
    Hi Don,

    I have some experience using microcontrollers and RGB LEDs but I'm not sure I would have much time to help. Anyway, here's an example controller circuit (below) that uses an 8 pin PIC microcontroller. The program produces 64 gamma corrected brightness levels per LED using duty cycle values spanning a 256 step PWM range and could probably be rewritten to run on a 6 pin PIC, like a 10F322, with a much higher refresh rate. You probably wouldn't need Sony SIRC Remote control capability and if you're just driving a single RGB LED you wouldn't need the driver transistors.

    May I ask what it is you're building, Sir?

    Regards, Mike
     
    Last edited: Oct 9, 2012
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Microchip has an app for that.

    The app note describes a simple controller with a PIC16HV615. They put a zener regulator on their sample, but this part can regulate its own power and can be left out. Might be completely unnecessary with the coin cell power you suggest. Also, the transistor outputs can be replaced with MOSFETs for lower component count, and lower current draw. If your LED current load is low enough the PIC could run the LEDs directly.
     
    MMcLaren likes this.
  4. Audioguru

    New Member

    Dec 20, 2007
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    A CR2032 cell is only 3V which is not enough to light most blue or bright green LEDs.
    The capacity of a CR2032 cell is so low that it will not light a red LED for long.

    The CR2032 cell is rated for a load current of only 0.19mA which is 1/100th the current of a bright ordinary LED.
     
  5. don.key

    Thread Starter New Member

    Oct 9, 2012
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    0
    Hi Mike and everyone, thank you very much for advises. I need this for toy robot for kids, it goes into robot's head. I have two 1209 SMD LED's in place now connected to one CR2032 battery, this lasts quite a long time and make kids happy.

    Now the idea is to replace those with two PLCC RGB leds and make them slowly change color. Eventually maybe even put in switch to choose some patterns, rainbow for 'peace', red glow for 'rage' e.t.c....

    Problem is: I have no idea how this all works and there is very little space available which will not allow me to put any other type of battery or large PCB inside :(

    I must admit that I am complete 'Dummy' as far as micro controllers and electronics hardware are concerned. I do code quite a lot but on a different level (UNIX Developer / Sysadmin), I can also solder very well but only when I know which part goes where :), without much understanding what they actually do.

    What would be a good place to start to learn it all? Perhaps this: http://www.nerdkits.com/kits/ ? Or is there a better kit?
     
    Last edited: Oct 9, 2012
  6. BMorse

    Senior Member

    Sep 26, 2009
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  7. Audioguru

    New Member

    Dec 20, 2007
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    Some of my cheap solar garden lights slowly change from red to yellow to green to aqua to blue then to purple before repeating. They show the 7th colour black when turned off.
     
  8. BMorse

    Senior Member

    Sep 26, 2009
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    White is the 7th color when all 3 LED's are on most RGB combinations.... black is off, not considered a "color".
     
  9. Audioguru

    New Member

    Dec 20, 2007
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    My solar garden lights never turn on all 3 colours at the same time to make white. They just add two adjacent colours.

    My homemade Mood Lights have separate slowly ramping circuits that randomly add all 3 colours and make millions of colours.
     
  10. Wendy

    Moderator

    Mar 24, 2008
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    agroom likes this.
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