Rgb controller

Discussion in 'General Electronics Chat' started by h2opolo, Mar 23, 2014.

  1. h2opolo

    Thread Starter Member

    Aug 2, 2013
    38
    0
    I had a general question about rgb controllers. I was looking at the specs for two different rgb lights--a 10W and 100W. (The specs are shown below) It is my understanding (though not completely sure) that the colors are controlled by manipulating the voltage going to the led. For example for the 10W, to display green, you have 0v on red and blue and 9-12v on green. For any colors in between you can apply voltage to different colors to mix them... My question is... There is a difference between the 100W and 10W voltage requirements for a given color. For green the 10W requires 9-10v and for the 100W, it requires 30-36v. How do you know what kind of rgb controller/driver will work for different led's?
    Thanks for reading!

    Model : 10W
    Color: RGB
    DC Forward Voltage (VF): Red 6-8V, Green 9-12V, Blue 9-12V
    DC Forward current (IF): 300MA
    Out put Lumens: Red 120-150LM, Green 200-300LM, Blue 70-100LM
    Wave Length : Red 620-625nm , Green 515-520nm, Blue 455-460nm
    Beam Angel: 140 degrees
    Life span: >50,000 hours

    LED Emitter: 100W
    Power: 90W
    Emitted Color : RGB
    DC Power Input: R:18-24V G:30-36V B:30-36V
    Color Temperature: R:620-625NM,G:520-525NM,B:450-455NM
    Intensity Luminous: R:1500-1800LM,G:2000-2500L,B:400-500LM
     
  2. #12

    Expert

    Nov 30, 2010
    16,252
    6,751
    LEDs respond to current, not voltage. Your mission, should you decide to accept it, is to provide current drivers that can achieve at least the voltage required to run the LEDs.

    Do you wish to explore how current drivers work or how to build one?
     
  3. h2opolo

    Thread Starter Member

    Aug 2, 2013
    38
    0
    In the future I plan to learn to build my own driver and controller so I could control the lights exactly how I want but at the moment I am just learning the basics.

    I tried this but I'm not sure it is correct... So if P=IV... P/V=I... If your led is 100W, and to display green you need 36V, your controller will have to be able to supply a 100W/36V (2.7A) current. If you want to run red you would need 100W/18V (5.6A).. So it would seem to me that I would need at least a 6 amp driver?

    I found a controller with the following specs and since it is 4 amp by 3 channels, is it correct to say this would not work to drive this unless maybe you run two channels in parallel?

    Supply voltage: DC12-24V
    Max Output current: 4A (each channel)
    3 channels
     
  4. #12

    Expert

    Nov 30, 2010
    16,252
    6,751
    Right. 4 amps will run the 10 watt, but not the 100 watt lights.
    and, it's better to get one supply that is sufficient so you don't have to be concerned with whether they will fight each other. To a designer, this is trivial, but when buying retail products, you always have to consider the unknown and investigate it.

    In fact, the specifications you provided do not tell the whole story. A 30% variation in voltage might be how the LED responds to current or it might be about how they are arranged with their own current controllers to accept that range of voltages. Right now, part of this is still my best guess.
     
  5. Little Ghostman

    Member

    Jan 1, 2014
    294
    97
    Ignore the life spec unless you have first class heat sinking! They cheat with heat figures and life span, the figures are for free air. Or in other words most places you dont need a light, On my fishtank I have 3W & 10W ones, in the end I used a TEG to cool them. I hooked the wires to a fan on top of the TEGs heat sink, when it starts getting hot it runs the fan, no battery required :D. but mostly I used them because on top of the led's heat sink they seem to really shift the heat away
     
  6. #12

    Expert

    Nov 30, 2010
    16,252
    6,751
    LG...You wanna tell the person with 2 posts what a TEG is?
     
  7. h2opolo

    Thread Starter Member

    Aug 2, 2013
    38
    0
    Thanks for the heads up. I don't expect them to last that long. I figured these things are cheap enough to buy new ones when they break (I would be thrilled if they lasted 1/4 of their rated life span)... As for a heat sink, I will be mounting it to an aluminum or brass surface and water cooling it.

    #12 -- thanks for your input although I'm not quite sure if I understood you correctly. From your comment before you mentioned the specs not telling the whole story. Is this because I am missing a piece of information or is this because the specs don't always tell if something is going to work properly together?

    You said the 10W would work but the 100W would be too much ... Was my reasoning correct with P=IV? I like the controller i found because it comes with an RF remote so I would like to use it. Is it possible to run two of its channels in parallel to double the amperage? Otherwise I found a different led that's 50 watts that is a reasonable compromise if it works.

    So at the lowest voltage it would draw the highest current at 59W/22V=2.3A... It seems to me that I could easily put 1 of these on each channel although I would prefer to find a stronger controller that could handle the 100w

    50Watt SMD RGB LED Lamp Bright Light High Power bulb Chip
    Model: 50W
    Color: RGB
    DC Forward Voltage (VF): Red 22-24V, Greed 32-34V, Blue32-34V
    DC Forward current (IF): 300MA
    Out put Lumens: Red 400-500LM, Green 600-800LM, Blue 200-300LM
    Wave Length : Red 620-625nm , Green 515-520nm, Blue 455-460nm
    Beam Angel: 160 degrees
     
  8. #12

    Expert

    Nov 30, 2010
    16,252
    6,751
    It's because I was missing a piece of information.
    Apparently these are single LEDs...just an LED...no circuitry attached
    so the variation in voltage is merely the way the LEDs react to current flow.

    Yes, Watts Law works for these, but the specifications are a range of voltages, so it takes some good judgment if they don't list the current requirements.

    I don't know if you can run 2 channels of your power supply connected together. Probably, "yes" but I wouldn't bet anything unless I measured it.

    LEDs are supposed to be rated in terms of current, like the 10 watt LED. You give it 300 ma on each wire (except common) and whatever voltage THAT particular LED wants is the voltage you will be able to measure on the power wire. You can't connect one supply to all three input wires because each LED will want its own voltage. The idea of a one or two channel current driver running a 3 color LED seems completely wrong. You might be able to put the three elements in series, but you haven't told me how many wires each LED has. Another piece of missing information that makes my answers equal to a best guess scenario.

    ps, a TEG is a thermo-electric generator. It turns electricity into cold. Pretty slick!
     
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