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Simple LED fader

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  • February 7, 2011 at 8:04 am #657
    Kigongo
    Participant
    Hi there! I’m looking to build a little project, but I don’t really know where to start.

    I want to have 3 fader-type potentiometers that will control the R, G and B parts of an RGB LED. I have a bit of experience with micro controllers and it’s something that would be easy with that, but I want to build it as an analog circuit.

    The things I know are this:
    I’ll need to use a transistor to control the voltage to the LED from the battery, as a pot would die a quick death otherwise.

    Any one have any tips regarding how to start? Should I just breadboard something up and try things until it works?

    Thanks!

     
     
    February 7, 2011 at 8:06 am #5447
    Agoston
    Participant

    You really want the pots to control the current of a variable constant current source.

    Basically, you have a sense resistor in series with the LED and you use an op-amp to compare the voltage across the sense resistor with the voltage on the pot.

    An alternative is to use the pot to control the duty cycle of a PWM signal used to power the LED(s).

    October 14, 2011 at 5:43 pm #6710
    vinod s
    Participant

    For an Ideal control of LED brightness, PWM is the right choice and the most commonly used one(as others replied)…

     

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