LED Driver help

Discussion in 'General Electronics Chat' started by thom7215, Apr 16, 2014.

  1. thom7215

    Thread Starter New Member

    Apr 16, 2014
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    I have scoured the internet for a couple of weeks on trying to figure out how to pick the right driver for my leds. My knowledge is extremely limited at wiring and volts, watts, and amps. If anyone could save me another two weeks of research I would greatly appreciate it. Here is what I have.
    1W UV Ultra Violet Hihg power LED 1Watt LED 395-405nm with 20mm Star Base
    these are the specs.
    Specifications:

    LED Emitter: 1W

    - Output Lumens: 6-7 Lumens

    - DC Forward Voltage (VF) : 3.2-3.8Vdc

    - DC Forward Currect (IF) : 350mA

    - wavelength: 395nm~405nm

    - Beam Angle: 120 degrees

    - LifeSpan Time : > 50,000 hours

    I will be using 20 of these LEDs. I want to know the specs on the driver(s) that I need to buy to go with these LEDs. Also, I need maximum brightness.
    Thank you in advance.
    JT
     
  2. wayneh

    Expert

    Sep 9, 2010
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    3,038
    Can you elaborate on that a bit more? Do you want them all on, at the same (full?) brightness at the same time?

    If so, you will likely want a series-parallel arrangement such as 4 parallel strings of 5 LEDs in series. The driver(s) you need depends how many parallel strings - channels - you have. Each string needs current controlled to <350mA, or you will damage the LEDs. The total current you need will be ~350mA times the number of channels. Current control can be as simple as a resistor in series with the LEDs but a better approach is a constant current supply for each channel. People lean towards higher voltages since this reduces the number of channels, and the total current, that you need.
     
    Last edited: Apr 16, 2014
  3. thom7215

    Thread Starter New Member

    Apr 16, 2014
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    thank you for the reply.
    So you're saying I need a driver with no more than 1.4A output?
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    I'd recommend 2 drivers with 10 LEDs (in series) on each driver..
    Driver would need to be
    10 x 3.2 = 32VDC min output
    10 x 3.8 = 38VDC max output or greater..
    350mA..
    I'd HIGHLY recommend running them at less than that if you want any decent lifespan out of them.. The short wavelength and heat created will burn/discolor the silicone lens on the LEDs in no time at 350mA.. And make sure your heatsink is sufficient to keep temps as low as possible (40-50 deg C max or less measured as close to the LED junction as possible)

    Personally I'd buy 2 x meanwell LPF-16D-48 drivers and pick up a 100k ohm potentiometer for each to do dimming if you want or to reduce the 340mA slightly (or a 75K fixed resistor across the dimming wires will give you approx 255mA output.. )


    And the only reason I'm recommending splitting them over 2 drivers is to stay with sub 60VDC drivers for safety.. Anything over 60V requires extra insulation/etc.. for human safety/touch protection.
     
  5. thom7215

    Thread Starter New Member

    Apr 16, 2014
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    Would this work?
    LED driver

    Input Voltage:
    9-15V DC

    Input Current:
    2.4A MAX

    Output Voltage:
    15.5-36V DC

    Output Current:
    340mA±2.5%

    Output Power:
    12W MAX

    And if they will can I use a 12v 2a wall wart to plug them in to?
    Forgive me if I'm asking stupid questions. I know absolutely nothing about this stuff.
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    You can run 9 in series with that driver..as 38>36 (maybe 10 if the Vf stays below the max)
    No dimming/current adjustment either..

    Personally I stay away from cheap Chinese LED drivers.. There are numerous cases of them failing quickly and some even causing fires..
    "You get what you pay for"..

    Meanwells are made in Taiwan (many of then anyways) and are of MUCH..MUCH higher quality. Its very rare to find a meanwell that has failed..
     
  7. thom7215

    Thread Starter New Member

    Apr 16, 2014
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    thanks. I don't need any dimming. I am making a screen printing exposure unit. I guess I'll get the meanwell ones. Do they have a plug on them?
     
  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    No as they are universal voltage you slap on the appropriate plug for your country..
    Datasheet is here..
    http://www.meanwell.com/search/LPF-16D/LPF-16D-spec.pdf

    You can buy them from here.. Assuming US..
    http://www.onlinecomponents.com/mean-well-lpf16d48.html?p=44296444

    There are some meanwells that are slightly cheaper without dimming but for the extra dollar or so I'd recommend having it just in case.. If you don't need dimming just tape off/protect the wire ends and don't attach anything to them..
     
  9. thom7215

    Thread Starter New Member

    Apr 16, 2014
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    thank you for all of your help. This has been a real headache trying to figure out as I hate to ask for help. I'll get them all wired up and let you know how it worked out.
     
  10. thom7215

    Thread Starter New Member

    Apr 16, 2014
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    ok, so i've wired all of the leds together and connected to the drivers. now I need to integrate this timer relay so I can set them to come on for a certain amount of time then shut off automatically when the time is up. Any more help or suggestions would be greatly appreciated. Once again I have done a lot of googling with no answers. Here is a picture of the relay and the diagram on the side.
     
  11. wayneh

    Expert

    Sep 9, 2010
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    Can you be more specific about where you are hung up? The LED drivers will of course be under control of the relays output pins 6,8 and 12.

    The instructions for the relay should describe what you need on the gate and reset pins to control the relay. It looks like the relay itself will supply 12V but again, read the manual.
     
    Last edited: May 2, 2014
  12. thom7215

    Thread Starter New Member

    Apr 16, 2014
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    I just need to connect the power cord and two drivers to it. The instructions do not tell you how to wire it. only how to use the display. the diagram on the side is the only instruction for wiring.
     
  13. wayneh

    Expert

    Sep 9, 2010
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    Can you link to a pdf of the instructions? Surely they describe what the "gate" and "reset" pins require?
     
  14. thom7215

    Thread Starter New Member

    Apr 16, 2014
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  15. wayneh

    Expert

    Sep 9, 2010
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    At least that describes the functions; the gate disables advance of the timer and reset sets the timer back to zero. Great.

    What's still unclear to me is what signals are needed on those pins. Maybe someone familiar with industrial controls can read between the lines. Whoever wrote those instructions assumed we already knew what was needed and didn't feel they needed to write detailed instructions.

    My guess is that you can choose (as the instructions describe) whether a voltage or a ground will trigger those two pins, and that the voltage it needs is the 12V DC also provided at the 12V output pins. Just a guess.
     
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