RGB's in my fading circuit?

Discussion in 'The Projects Forum' started by brozizds, Feb 17, 2011.

  1. brozizds

    Thread Starter Active Member

    Aug 15, 2010
    135
    0
    I tried posting this question in my led fading tread but got no reply so I'm starting a new tread to try and get help.
    I am trying to replace my three color string of leds (red, white and blue) with RGB Led's. I have a few questions. How do you control combination colors? I'm thinking that RGBs are treated like 3 separate leds ( red,green,and blue) with a resistor for each pin but is there a way to control the color combination you want? I did look at Bill Marsdens (Millions of colors article) but I still need a bit more help! Here is the final schematic and the circuit is working perfectly(Thanks Bill) and also thanks for the tutorial on making PCBs.
    http://forum.allaboutcircuits.com/showpost.php?p=312703&postcount=44
    Thank you Jim :confused:
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    What's up guy, you should have PM'ed me.

    There will need to be a minor redesign, but I don't think it is a big deal. The resistors will need to be moved to the Drain of the transistors, which will allow the RGB LEDs to be connected to Vcc. The resistors could be soldered directly to the LEDs, or to the wire outputs and the wires connected to the resistors instead.

    http://forum.allaboutcircuits.com/showpost.php?p=309649&postcount=24

    The RGB LEDs must be common anode.
     
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  3. brozizds

    Thread Starter Active Member

    Aug 15, 2010
    135
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    Thanks Bill I know how busy you are so I thought I best post this just incase. PS I wasen't sure if I should PM or not! I didn't want to break any AAC rules .By the way my PCBs are comming out great THANKS! I used a Variable speed jig saw to agitate the etching solution (LOL and it was great!) The tupperware rocked gently back n forth. Wife just smiled!
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    You may want to change the board to reflect the change in circuitry.

    One side point, the original design used LEDs in series. With RGB LEDs this is not an option, so the resistors are going to get a bit hotter, and the design will absorb a bit more current. You will likely need more resistors too, 3 for each LED. The MOSFETs are overrated enough I doubt they'll be a problem, but I have no way of knowing what your final panel design will be.
     
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  5. lespaul

    Active Member

    Jan 30, 2008
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