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Thread: White LED experiment

  1. #9

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    Hello. I'm doing a theoretical 735mA, although the actual value may vary. Mine is not dimmable, other than through pwm. I'm using 27 degree lens.

    I'm using the following combinations (where blue is royal blue)

    3 blue
    2 blue 1 red
    1 blue 2 red
    3 red
    3 ansi white 4000k
    3 4100k neutral white (i bought these by accident since I did not know about the ansi whites, so might as well use them too!)

    I'm still a bit far from getting everything up and running. I'm still soldering my constant current drivers. I'm planning to experiment on gemmae.

    Can I ask how far are you planning to place the lights from your plants? I have not decided on that yet, but in order for the 3 85lm leds to match half of 4 5000lm T5s placed 40cm from my plants in flux (which my pygmies are currently under, half since they are kinda off to one side), I have to do something like 6.3cm from my plants, which I would assume to be too close. Using the current optics I have, the radius of light does not fill a pot.

    Edit: also, where did you get your spectrometer? I would like to have one too to play around with. I tried ebay, but I'm getting very expensive lab versions.

  2. #10
    Av8tor1's Avatar
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    Im not sure how far to place them. I did experiment the the Grow Master LED plant light LGM5 for about a year and it stated to use about a 24" distance.

    One issue with it (and most other individual LED designs IMHO) was the spectral blending... so the distance was needed in part to let the colors combine. In addition the luminance of the LED's will be extremely high due to their small size and power level.

    This was another reason for my thoughts on a dimmable driver module and the 22 degree lens... but so much of this is just a best guesstimate at this point

    Question.... what did you decide on for thermal transfer.... Paste, glue or tape?
    I found a thermal silicone glue that was getting some real good reviews and cheap to boot so I ordered a tube of it. My only experiences with thermal tape have been less then satisfactory in high temp applications.

    Thermal glue

    Ive got three spectrometers and by far the best is: http://scientificsonline.com/product...:referralID=NA

    Here is a pic of that LGM5 from a distance of about 4 foot, notice the spectral blending and luminance



    Av
    Last edited by Av8tor1; 05-19-2010 at 08:48 AM.

  3. #11

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    I am also worried about the blending, but I'm thinking if I sacrifice the lm per area, I can place it further for a better blend. The T5s are probably way too bright to do a fair comparison anyway.

    I'm using Arctic Silver Thermal Adhesive. It hardens and isn't elastic. It also binds things together for basically forever, so that might be an advantage or disadvantage depending on how you look at it. It's a little bit more expensive, but I heard good reviews about the brand too. I got mine off ebay.

    Thanks for the link to the the spectrometer, I'll definitely have to pick one of those up.

    Also, nice lights there. Are you going with 5 tristars or will there be more?

  4. #12
    Av8tor1's Avatar
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    At this point and price level its just trials for me... but IMHO with the wide selection of aux optics it kind of depends on application. For low canopy applications, a less distance to plant, wider lens angle and fewer tristars might be the trick. For taller plants like neps where a deeper canopy penetration is required, a greater distance, tighter lens angle and more tristars might perform most efficiently.


    A lot of unknown variables and a lot to learn

  5. #13
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    Quote Originally Posted by Av8tor1 View Post
    Ive got three spectrometers and by far the best is: http://scientificsonline.com/product...:referralID=NA
    Hi Av,

    Do you know who is the manufacturer of the spectometer? Unfortunatley, the above linked company does not ship to the UK so I was wanting to see if I could find a stockists here.

    Thanks,

    Carl

  6. #14
    Av8tor1's Avatar
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    Carl,

    It'spretty widely available... google "project star spectrometer"

    I noticed a UK source on the first page of search hits

    Butch

  7. #15

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    Av8tor1,

    What exactly is the benefit of having a higher CRI index? I was under the impression that spectrum and intensity were the only relevant factors for plants. In fact, because photosynthesis is only occurring in part of the visual spectrum, wouldn't theoretically ideal light render colors poorly?

  8. #16
    Av8tor1's Avatar
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    Ent, so much of the tribal knowledge is based on a single red and blue wavelength. But as the NASA research has shown the spectral needs of plants are not all the same. In addition you have accessory pigments, beneficial organisms and phytopathogens that are all affected by certain wavelengths. But for me its having a energy efficient plant light that is not only a high performer but is also aesthetically pleasing.

    I've tried the traditional LED format and found it to be a good "supplement" but unsatisfactory as the primary lighting source.

    If i can have all the advantages of LED's and at the same time have a "true" white light then that's the holy grail of plant lighting IMHO

    I will have reaced LED Nirvana

    People have been trying the Red/Blue based LED's now for a few years... For many they find that in the real world it's just not quite enough for long term plant performance. Basically once you start adding in these additional needed wavelengths you are back to "white"

    If I grew only one species and had no concern other then plant mass, then a couple specific wavelengths are more feasible

    Of course this is also a personal preference and personal opinion thing, I'm looking for a LED that performs like a T5, LED and HID hybrid, but at a fraction of the energy cost.
    Last edited by Av8tor1; 05-26-2010 at 11:26 AM.

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