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Thoughts on DIY LED

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  • Thoughts on DIY LED

    Here's a way to go on the cheap, but just as good, if not better, as any commercial unit. It's like cooking at home instead of eating out. You know what has been put in the pan and what you'll be shoving into your mouth. Don't you grow your own for the same reason? Economical + Safe!

    First of all, figure out your target spectrum in order to pick the right LEDs. To that, there is not much to say. You will need 430nm, 460nm, 630nm, 660nm and some lesser important wavelenghts. I hope every guru agrees about that...

    Here, there are still two paths to go. Full spectrum (Bridgelux and the like) or discrete LEDs. The frst one is "table d'hôte" and the other is more "à la carte". But the discrete option could let you pick a different spectrum for each stage of development of your crop. Not a bad thing, after all, bearing in mind the spinning wheel in the electric counter. Isn't that why we go LED? Not to pay for the "green" and in that instance, not to pay for too much "blue" or "red" when not needed. You get the point? I hope.

    So, we wanna go cheap, don't we? Then, we'll go ebay and China source. This is our first problem. How can we be certain that what we buy is what is advertised. There is no way to know for sure. But it won't stop us. Most probably, those outlets sell second rate BINs rejected as "prime" by Cree, Osram and the like. As far as light output is concerned, it is not important. At worst, you'll be using your lights closer or not cover as much ground as expected. It's just a matter of quantity. But for the color itself, we are in trouble.

    They may as well have the exact same blue LED labelled as 430nm and 460nm and the same may go for the red 630nm and 660nm. Actually, if you go to a proper electronics store on-line, you will notice that 430nm and 660nm are not too common. They are, so to speak, the rare kind. But at least, if we only get 460's and 630's, they respectively hit both chlorophill bands. We'll get to that problem later on.

    Before we go further, we must understand how a LED works and mostly, how a white LED works. A LED is a device that produces light in a very narrow single color band. A white LED is roughly a UV or blue LED that has enough energy to excite a phosphor, just like voltage does in a fluorescent tube. As far as those "full spectrum" LEDs are concerned, they are white LEDs with a phosphor lean in green. There goes the reassuring pinkish color that we all like.

    So, here we are and there we go. Let's assume that all that we have are 460's and 630's. That should be enough. But what about 430 and 660? If a full spectrum LED that is lean in green can spill into violet and deep red, so will a white LED. The solution, thus, is to complement our blue and red with a small amount of cold white and warm white. The full spectrum should be well covered.

    In a next posting, I will be writing about the electrical end of things. You think you need a fancy LED driver? My eye. A simple wall wart can do the job, given enough guts and power, obviously.

    So long...
    Last edited by rouelibre; 01-06-2017, 06:47 AM.

  • #2
    Thanks for posting . Good reading.....

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