LED experiments begin

[Mrobert]

I believe current off-the-shelf solutions are overpriced and I have not seen conclusive independent proof that these lights deliver as promised. I also have no way if verifying that the diodes being used are the same diodes that they say they use. So...

I've decided to get custom LED fixtures fabricated and then conduct tests of my own on/with the arrays I've created.

I've contacted an electrical engineer and we are currently in the prototyping phase. For the first prototype we are going to cover the wavelengths already known to be important to photosynthesis. From there, well, I'm open to suggestions. To start with I'm going to make variations in number of diodes, diode wavelength mixes, beam spread, and intensity will follow (this is going to be a long process).

I do not have the prototype "in hand" and I can't even give you an estimated time-frame, but I promise to keep this thread updated with pics, development issues, questions, and everything else.

PLEASE give me ideas, advice, or questions. I'm doing this for my collection but I'd really like to see a set of real world data generated.

Thanks- MR

[Ron-NY]

Thanks for the info, I will follow this thread. NASA has done research on LED lighting for growing plants in space. I bet you can find some of the info by Googleing

[Mrobert]

NASA, why didn't I think of that!?

[Diane]

I've been really interested in these - I'm very curious about mixes of color = ie one blue array with 2 red ones versus mixed arrays.

[Mrobert]

LEDs seem like a cure all: low power, low intensity to the human eye, cool, wavelength specific, sturdy, easy to replace (single diodes)...the only catch at this point is price, but according to the research I've done the OTS systems are way overpriced. I think when you by an LED system currently on the market you're paying for a lot of R&D.

[Ron-NY]

I am wondering about the light penetration. Do they need to be very close to the plants or can they be 4-5 feet above the plants. I am planning on building a "Wardian " case this winter.

[mycologist]

I believe current off-the-shelf solutions are overpriced and I have not seen conclusive independent proof that these lights deliver as promised. I also have no way if verifying that the diodes being used are the same diodes that they say they use. So...

I've decided to get custom LED fixtures fabricated and then conduct tests of my own on/with the arrays I've created.

I've contacted an electrical engineer and we are currently in the prototyping phase. For the first prototype we are going to cover the wavelengths already known to be important to photosynthesis. From there, well, I'm open to suggestions. To start with I'm going to make variations in number of diodes, diode wavelength mixes, beam spread, and intensity will follow (this is going to be a long process).

I do not have the prototype "in hand" and I can't even give you an estimated time-frame, but I promise to keep this thread updated with pics, development issues, questions, and everything else.

PLEASE give me ideas, advice, or questions. I'm doing this for my collection but I'd really like to see a set of real world data generated.

Thanks- MR

Another thing to consider along with the peak absorption areas for photosynthesis is the red/far red ratio (660nm/730nm if that is possible to get at). This is responsible for modulating the phytochrome receptors which trigger a number of important functions like flowering in some plants.
Phytochrome - Wikipedia, the free encyclopedia

[Mrobert]

Another thing to consider along with the peak absorption areas for photosynthesis is the red/far red ratio (660nm/730nm if that is possible to get at). This is responsible for modulating the phytochrome receptors which trigger a number of important functions like flowering in some plants.
Phytochrome - Wikipedia, the free encyclopedia

I agree with you on the photoreceptive wavelengths you've listed, but I believe there is another important part of the spectrum to get in the violet/blue area from ~400nm-475nm.
This link shows wavelength.
This link
should give you a good idea of what LEDs are generally available.

You'll notice that there is a 660nm diode, and 430-535nm is well represented.

PLEASE keep the feedback coming, it's forcing me to do more research!!!

[Mrobert]

I am wondering about the light penetration. Do they need to be very close to the plants or can they be 4-5 feet above the plants. I am planning on building a "Wardian " case this winter.

I don't know about penetration, that will have to be revealed during my testing phase. The immutable law of physics we're up against is here, we lose intensity by 1/distance-squared.

However, you could make a really nice Wardian case, in fact it's the best application I can think of. The size of the LEDs will allow you to hide them nearly anywhere, and if you put add color changing LEDs or "true color" LEDs lots of interesting opportunities present themselves.

[Ron-NY]

the inverse square law is my concern even with considering the use of fluorescents. I have been looking into a semi mirrored glass, with the mirror surface facing into the case to allow light to be bounced back in from the internal light source. The case will be for lower light species. Mostly Bulbos.

Do you know of a reference where I can learn how to assemble my own LED lighting?