Dimming High Power LEDs?

Discussion in 'The Projects Forum' started by GRNDPNDR, Mar 18, 2014.

  1. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    I ordered one of these 50W LED drivers a couple of weeks ago to power a 30W LED that I have, it's a large square with about 9 small high powered LEDs in it.

    I'd like to throw the driver in a project box and have the ability to dim the LED because it's like a small sun and I don't always want it running at full power.

    Would it be as easy as adding a pot to the output of the driver? or would the high power cause a problem with a normal pot?
     
  2. spinnaker

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  3. spinnaker

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    I am counting 3 wires on the one end of the board. Two on the other end. Is that right? If so what are the function of each wire? Could one be for dim?
     
  4. spinnaker

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    Nope looking at it again, looks like two on each end. But it appears there is an extra pad which appears to be labeled. It would be interesting to know it's function/

    One nice thing about the buckpuck I posted is that it has a 5V regulated out that you can use to power a 555 timer or a mcu.
     
  5. GRNDPNDR

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    Mar 1, 2012
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    Well I've already bought the driver on ebay, although I wish I knew about the buck puck a couple of weeks ago.

    I didn't think a pot would be a good solution, but is there something I can do to make the driver I purchased dimmable?
     
  6. spinnaker

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    You would have to have details on that device. I would bet it could be hacked but not sure how to do that. Some Google searching might yield something.
     
  7. GRNDPNDR

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    I guess I'll just wait until I receive it, maybe contact the seller and see if I can get a schematic.

    What kind of details would be needed failing a schematic?
     
  8. THE_RB

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    Good photos of both sides of the PCB. :)
     
  9. mcgyvr

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    Oct 15, 2009
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    When you want dimming I always recommend a meanwell LPF driver.. (about $20-30 usd)
    It can be dimmed by 10V pwm or 0-10V dc or 100k potentiometer.
    like this
    http://www.meanwell.com/search/LPF-25D/LPF-25D-spec.pdf
    LPF-25D-15

    be careful with putting those Chinese ones in a box or any driver for that matter.. they will need vent/fan to avoid overheating.
     
  10. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    No more money to spend on the project, so I'm working with what I've got.

    I contacted the seller and am unable to get a schematic so I guess I'm either going to get good high-res pics of the board or reverse engineer a schematic myself.

    For all I know it could take another few weeks to get here though. If it shows up at all.

    One time I ordered some pond foggers, after 30 days I got a refund.

    4 or so months later and they arrived in my mailbox.
     
  11. AnalogKid

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    Aug 1, 2013
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    The brown and blue wires are the AC input (European color system), and the red and black are the DC output (red is +). Some boards have a 3rd input wire; that is the safety ground, or Earth ground, usually green with a yellow stripe. If the third pad is on the input side, it's probably for the ground. On a board like this, a connection to an external device like a dimming pot usually has all of the connections arranged for a connector, so I'd expect two or three extra connection points instead of just one.

    ak
     
  12. GRNDPNDR

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    Mar 1, 2012
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    Well,it seems I've made a small error with this I think.

    Driving power: 50w
    Model: 10 series 5 in parallel
    Input Voltage: 85V~265V
    Output Voltage: 32-34V
    Current:1750mA
    Efficiency > 88%
    Power Factor >0.98
    Operating Temperature: -20~80
    Size (L * W * H): 110mm * 32mm * 23 mm


    it's output voltage is too high, so I'd have to do something to step it down to 12V but still giving me the current carrying capabilities.
     
  13. spinnaker

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    You don't need to be concerned with too high of a voltage with LEDs. Your concerns are too low of a voltage to drive the LEDs and too high of a current that will either burn them out or at least shorten their lifespan.
     
  14. GRNDPNDR

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    Mar 1, 2012
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    I know the LED is only going to draw what it needs, but if this thing outputs 32V at the lowest, and the LED is 12V, then it's pretty safe to say the LED will burn out.

    It says output minimum is 32V.
     
  15. GRNDPNDR

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    Mar 1, 2012
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    Actually I'm lso just noticing that they have the drivers pictured the with the exact type of LED I'm powering.

    I didn't see that before, but now I'm curious. I'm going to plug this in shortly and measure it's output, but I'd be hesitant to put 32V to the LED even though it looks the same as the ones in the picture only it's 30W.
     
  16. spinnaker

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    Current is the killer. If that is regulated then you will be fine.
     
  17. GRNDPNDR

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    Mar 1, 2012
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    so if this is constant current, it's going to feed the LED with 1750mA instead of letting the LED take what it needs?
     
  18. spinnaker

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    The driver should regulate to what ever it is set to. My worry is that (from memory) the specs were in watts? If so then voltage would be an issue since watts is a function of voltage and current. But if you have a true spec on current limitation and it is what you need then you should be good to go.
     
  19. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    Well, I clearly didn't think the entire purchase through.

    I purchased a 50W driver because you shouldn't run devices at max spec, so I thought there would be some overhead.

    I didn't realize this would be a current limited device (still unknown until I test it), because if this is truly the case, then I have too much power.

    50W driver, 30W LED.

    I'm just sitting here having a few drinks and being too lazy to get off my keister to go check.
     
  20. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    oh also, how could I test it's current output and if it's constant? I don't have a 50W DC load.
     
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