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Constant current power supply recommendation for 3W Star RGB LED

Discussion in 'Power Electronics' started by flashdom, Dec 3, 2012.

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  1. flashdom

    flashdom

    18
    0
    May 21, 2010
    I'm having trouble finding suitable power supply for this led:

    http://dx.com/p/3w-led-emitter-on-star-multicolored-rgb-4530


    Ideally I would like to power 3 of these at once to get 9w of total power. I would also need to be able to power all colors at once as well as any combination or each color.

    I would probably need 3 power supplies for each color. Red is the only that has different voltage. It will be controlled by arduino uno.

    Can anyone recommend a psu preferably from dx.com or other supplier that ships internationally with reasonable rates.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,412
    2,780
    Jan 21, 2010
    Since this LED has 4 leads, one is common (the anode), so you cant connect them in series. You need to drive them in parallel, which means a controller for each led, or resistors to encourage current sharing.

    I would suggest that each colour is probably 1W, so you need a controller for red, green, and blue, each of which is capable of driving a 3W LED.

    Without knowing what you actually want to do, it's harder to be more specific.
     
  3. flashdom

    flashdom

    18
    0
    May 21, 2010
    Its going to be a mood light. I also wanted just white for normal use as well. Can you elaborate on the controller? what do you mean by controller exactly? I would be happy to just use 1 led for now if that simplifies things a lot :)
     
  4. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    If you read the threads bellow the product there is a driver that someone tinkered with and had decent results...

    http://club.dx.com/forums/forums.dx/threadid.963272

    This controller is the one they used, 3 per puck...

    http://dx.com/p/mr16-1-1w-320-350ma-constant-current-regulated-led-driver-8-40v-input-13553

    Not the most eloquent way to do it but you will be able to get it up and working without much hassle... As Steve suggest without knowing all the details of your project and the fact that these are common anode makes specific designs harder to suggest...
     
  5. flashdom

    flashdom

    18
    0
    May 21, 2010
    Nice find, I actually have some of these psu's. It is annoying though since it requires ac/dc converter... I will try to get that to work but in the long run I would like something that works 100% as expected(ability to turn off each color completely etc...).

    My plan was to have 3 of these led's connected in series (each color). drive each color with 900-1050ma constant current supply and simply use arduino with a transistor to dim each color/psu.

    It seems to me like there are 2 problems with my plan: 1: led's need to be cathodes not anodes. 2: constant current psu may not be dimmable. So assuming I get some cathode led's and a constant current psu that is exactly or just below the total power (ma) of the led's in series this would work? Or do constant current psu's don't dim easily? Do I need special dimmable constant current psu?
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,412
    2,780
    Jan 21, 2010
    Here is a controller that does PWM to control three channels giving you a variety of colours.

    Most importantly it is for common anode LEDs.

    HOWEVER this controller DOES NOT have a constant current driver, so you need to figure out how you're going to do that.

    There are many more of these available. I purchased one for a string of LEDs that was less than half this price.

    Also, since these operate from a minimum of 12V, that may be troublesome too.

    The output of this might be able to be used to control the PWM input of other constant current drivers though. Doing that would still simplify your task greatly.

    What you would need to find is a constant current source which uses a chip that has a PWM input.
     
  7. flashdom

    flashdom

    18
    0
    May 21, 2010
    I'm still confused about one thing. Can standard (+/- I/O only) constant current supplies be dimmed with PWM (as in arduino) without drawbacks/issues? I've seen this question asked and answer was yes they can but from your post it seems like maybe not. Can you clarify? Since multiple leds seems too complex I think I will go for 1 led and 3 power supplies for each color and while I'm at that I will go high power (30w).
     
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