Multi-color LED controller

Discussion in 'The Projects Forum' started by jpferrierjr, May 28, 2010.

  1. jpferrierjr

    jpferrierjr Thread Starter New Member

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    I'm trying to build a circuit that uses multiple multi-color LEDs. I'm wanting this circuit the be able to create all possible colors with one potentiometer. It's really racking my brain (I'm a noob. Also, it doesn't help not knowing anything about ICs). I can easily figure out a 3-4 knob system. But, it just wont work for the application. could anyone suggest anything? I can figure the exact resistance and such that I'll need. I just need a basic layout. Thanks for the help! :confused:
  2. beenthere

    beenthere AAC Fanatic!

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    That is a tall order, as an RGB LED has three elements that make the colors (now one of the Japanese outfits is including a yellow LED for a better spectrum). See the link - http://www.sparkfun.com/commerce/product_info.php?products_id=105

    About the only way to get there from a single control would be to use a microprocessor (and perhaps an external ADC for the required precision) to read the control setting and translate that to three PWM streams to control those three LED's.

    Someone else may have another approach.
  3. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    It can be done pretty easily with 3 pots. It can also be done with 3 fader oscillators, where the colors come up pretty much at random.
  4. jpferrierjr

    jpferrierjr Thread Starter New Member

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    Thanks guys. I might of found a solution, though. I found an IC that's made to handle it. I believe it was called an aat3129. I really appreciate your guys' help! Thanks!
  5. beenthere

    beenthere AAC Fanatic!

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  6. jpferrierjr

    jpferrierjr Thread Starter New Member

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    Ugh... Yep. I'm a noob. So, what's a serial digital input? Would I need to construct a circuit that translates voltage (from the pot) to faster and slower frequencies? This is much more complicated than I was thinking it would be.
  7. beenthere

    beenthere AAC Fanatic!

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    Go to the link and get the data sheet. The serial data is something that would come from a programmed microcontroller. See my post #2.
  8. jpferrierjr

    jpferrierjr Thread Starter New Member

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    Do you think I could use a pot to control a 555 and use the resultant sig from that into the aat3129 and program the aat to react to different timings? I'm also a newb with "C" programming. But, I could teach myself.
  9. beenthere

    beenthere AAC Fanatic!

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    No, unfortunately. The serial data carries meaning beyond simple frequency, as the pulses are organized as control words. The controller IC has internal logic that responds to the serial digital control words. The formatting and generation must be done external to the actual controller.

    Here is a slightly informative article - http://www.oomlout.com/RGBL/RGBL-Guide.pdf

    And a more detailed article - http://www.ledsmagazine.com/features/4/11/2

    The 555 approach is one that can work if the timers are set up to do PWM - plus you will need three of them to control each of the three LED's. The only way to have a single input do the full control is with a microprocessor to interpret the input according to a program.

    For some experimental fun, look up the topic "color organ" in the forums or with Google. You might find it interesting to make a three channel color organ to drive the LED's.
    Last edited: May 31, 2010
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