Custom LED panel + stealth dresser

Discussion in 'Growing Marijuana Indoors' started by crunkyeah, May 7, 2010.

  1. #1 crunkyeah, May 7, 2010
    Last edited by a moderator: May 7, 2010
    Just going to forewarn everyone here, this grow will take some time to assemble and get started. It will be a costly(for me) project. I will need to purchase a multimeter, a heat gun, power drill with hole saw bit, among other things that I simply don't have as of yet. On top of that, I want to finish my current grow which I expect to finish in 4-6 weeks. Link can be found in my signature.

    My plan is to build a stealth dresser cab. The dimensions for it are 29"L x 14"W x 37"H. By my calculations I will have 2.82 feet of square footage to work with and a measely 8.7 cubed feet. Because I don't have much space when it comes to height I have planned for this to be another scrog grow. I will be growing 1 plant. I haven't thought too much about which strain I'll be using as I have a few. I've got DNA's Skunk#1, LA woman, Lemon Skunk, Sharksbreath, Rocklock, and Chocolope. Also have a ton of bagseeds, but I'm not sure if I want to use an unknown strain. I originally planned on using the Chocolope but having a 95% sativa makes me wonder how flowering will go. If you have any suggestions out of the above I'd love to hear them and why you think I should grow that strain.

    Ventilation will be 4 PC fans mounted into the particle board backing the dresser has. I have some black tubing that will be hooked up to the outside of the cab to protect the light from escaping. The 2 exhaust tubes will be going to some sort of scrubber I have yet to build. But it will be 2 fans pushing air into it from both sides. I'm fairly certain the fans will be strong enough. They're the 90mm ones. And since I will only be growing 1 plant it will be a relatively thin type of carbon scrubber.

    Now onto the most important part of all: the lighting. I'm sure there will be a few people who may try to prove LEDs pointless. But in this case, trust me it's going to be good. I will be creating a custom LED panel made from Luxeon Rebel stars. I will be running them at 350mA to help with heat issues(and also maximum light output/longetivity). They come with a standard 120 degree viewing angle. If mounted at 2 ft this gives me a beam diameter of 6.9 feet! This is highly inefficient since most of my light will be bounced off the walls. I plan on using mylar but we know from CFL and HPS users that light that is reflected is less intense. So I'll be using 12 degree lenses on my diodes. This decreases my beam diameter to .42 feet per LED(roughly 5 inches a little more). The concept is like a flashlight, a highly focused intensely bright beam. This is unlike EVERY commercial LED unit on the market, including the UFO. With this specific system it's more efficient to focus that light as tight as I can get it without losing coverage.

    So with these high power LEDs you HAVE to have a heatsink. The heatsink I will be using is a durable aluminum with cooling fins attached. There is a picture below of what they look like. The one I will be using is 8.5" x 13". With the LEDs and lens added this will give me a roughly 13.5" x 18" coverage area. Because of the tightness of the LEDs I will also need side lighting to help disperse the light throughout the cab in a way that all of the plant gets coverage once it's grown into the screen. I will be using the 4 LED panels in my current grow mounted to the wall so that I have complete coverage. I will be mounting the LEDs to the heatsink with a thermal tape that luxeon sells along with their LEDs. This will be make it very user friendly and hassle-free.

    Now for the math of the LEDs:
    Red forward voltage @350mA - 2.9v
    Royal blue FV @350mA - 3.15

    I will be using 24 red and 6 blue. For a red:blue ratio of 4:1.
    I will have 4 sets of red and 1 set of blue between the reds.
    First I need to find the maximum voltage requirements I'll need from my power supply. For this I use the blues since they are higher. So 6 * 3.15v = 18.9v.
    Power supply must be at least 19v. Got it.
    Now for the amperage. 5 strings of LEDs at 350mA = 5 * .35A = 1.75A.
    As for the watts(using Ohm's Law):
    Red - 2.9v * .35A = 1.015w * 24(total reds) = 24.36w
    Blue - 3.15 * .35 = 1.1025w * 6(total blues) = 6.615w
    6.615 + 24.36 = 30.975w (~31w)
    So in total I will need a power supply that supplies 18v, 4A, 31w. I have found the Meanwell PLN-100-24. Specs are 24v, 4A, 96w. Also has current and voltage regulation(for the uneducated LEDs MUST MUST MUST have some current regulation or they WILL fry).

    So that's 31w of highly concentrated light coming from above. The panels I spoke of earlier run at 13.8w. And I'll be using 4 of them. 13.8 * 4 = 55.2w + 31w = 83.2w. Before you go on saying that isn't enough wattage I want to point out this is a MICRO grow for ONE plant. So I'm not looking for the most watts. I'm also doing this as an experiment to see if I can build a light that will grow a plant and flower it successfully.

    I'm not sure what I'm going to do about nutrients as I haven't used them really at all for my 2 previous grows(maybe got lucky and bag seed strains don't need much nutes). I think I'll be using a 10-12" pot and I'll try to find a wide one so roots have some stretching space. This will leave me with roughly 20-30 inches of vertical space to work with. I plan on giving her 10" of space before LSTing and adding the screen in. I think I've covered most of my bases, if I'm missing anything that anyone would like to know just ask and I'll let you know :)

    Now for the pictures: 1 is of the heatsink like I mentioned earlier. 1 is of the LED lens I'll be using. 1 of the power supply. 1 of the design array on the heatsink. 1 is how I (somewhat) expect the cab to look while it's in progress. Last is of the dresser not gutted yet.

    *edit* Forgot a very crucial aspect!!! The spectrums of course. The Luxeon Red LEDs I'll be using are 626nm and the royal blue are 447.5. The panels I purchased(I think they're a waste of money DO NOT buy them. I have them so I might as well use em I figure), have 165 red LEDs at 650nm and 65 blue at 465nm. In total I will have: 6x 447.5nm, 260x 465nm, 24x 626nm, and 660x 650nm. I know this does not include 660nm, but luxeon simply does not make any far red LEDs. I would have to change manufacturers and research a lot more just to get that spectrum. I think having 4 spectrums will be sufficient.

    Attached Files:

  2. 660 is very crucial for plants
  3. According to this video, [ame=""]here[/ame], 660 is not the most crucial red spectrum. Tomatoes are very genetically close to our beloved plant, I think the only being closer is the hops plant.

    Can you site your source please? I'd really like to see how 660 is more important that 630.
  4. A little update here for anyone who may be interested..

    I have decided against using the rebels. I did this mainly because higher wattage diodes will put out more light at the same amperage. What this means is that I'll have more light and less heat to dissipate. This is a very crucial part of any LED panel design. LEDs work significantly better at lower temperatures. So what I decided to do was use LedEngin's 10w diodes. They put out lots of light(4 chips) all while running at .7A(700mA). My first design consisted of 6 red and 2 blue 10w diodes until I discovered that the white LEDs cover the same spectrums. The white LEDs also cover minute amounts of UV and a little bit more of IR. Because of this I decided to scrap the red and blue LEDs altogether. The red LEDs may be usable, since the white LEDs don't cover as much red spectrum as red LEDs, but the blue LEDs in ANY application are pointless. The coolwhite LEDs I will be using put out the SAME amount of blue light as a blue LED, along with other spectrums, most notably in the UV region. More wavelengths for less LEDs, can't go wrong with that! I'm not sure if I'll add more red LEDs later on, but it seems white LEDs should cover everything I need them to.

    With the white LEDs I'll be able to cover all the needed spectrums. Using only 6 diodes will also help with heat dissipation. Each LED will have more surface area to dissipate the heat. Because of this I should see increases in light output as well as longetivity.

    Now here's the good part about these high watt diodes. I'll have increases in wattage compared to the luxeon panel. ~60w vs ~30w. I'll also see tremendous increases in light output since the white diodes have a higher luminous flux. Heat will stay about the same(luxeon panel running 1.75A, LedEngin 2.1A). The engin panel will be a little higher, but each LED will have more surface area, I reckon it will decrease temperatures which is what we want.

    Another bonus to using few high watt diodes compared to lots of smaller ones, is that I won't have to spend as much on the diodes. ~$230 luxeon vs ~$190 engin. Another cost factor that will help with money is that the LedEngin's do not have lenses. They just don't make them. This causes a little concern. The previous design was setup to focus the light into an intense beam and mount the panel high. Well with this panel mounted high, my coverage area would be like 10 feet, which means lots of light lost. So I'll be lowering the panel to about 6 inches or so during the veg stage. And drop it down to probably 3 inches at flowering. This should keep them very tight and compact, and I shouldn't see any stretching through the ScrOG screen.

    I have drawn up another design for the dresser, and the panel of course.

    Any questions/comments? Feel free to ask!

    Attached Files:


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