Red/Blue Balance

I got this email from Deltalight. He is from the person with whom I have been talking (actually pushing and prodding) concerning the creation of a more cost effective and energy efficient LED grow light.

Offered by Steve.

I have a dandy circuit that will allow the user to control frequency and duty cycle via two knobs. They would have a scale printed on the housing (like the graduations on a volume control like on a stereo). This way the user can independently control frequency and duty cycle for both RED and BLUE LEDs. This of course eliminates controlling them Via an external microprocessor, but it helps keep the cost down. Feel free to repost this message in any pertinent chat room.

Bill Mack
[email protected]

I am no expert on what intensity of red versus blue is optimum taking in to consideration price of each color of LED and plant growth that will result. I am assuming an optimum can be found. If NASA has found it and we can trust that number at 8% blue and 92% red both burning at the same frequency and relative intensity per LED then that is the answer. I think we can assume that the intensity of light is what is important. That there is nothing magical about certain frequencies causing growth (however this should be checked). I think this may be a safe assumption if we consider the Sun has no frequency to it and does quite a good job of growing plants.

Offered by Mike.

My point to Quantum was the research says 92% red and 8% blue so just do that and don't bother with the ability to modulate. However, if you want lots of leaves you would want more blue and if you want more fruit (tomatoes), less blue, so this sort of flexibility does have a place. At the same time, you can probably save a lot of money by just setting a standard and going with it en masse and it will do the job (i.e. how much do you have to pay for flexibility).

Offered by John.

None of that is necessary if the buyer would be willing to have just a "grow light" with a constant, fixed light output with the blue intensity and red intensity being at a level set to a nominal level. After talking with Steve and seeing what NASA was doing, the other folks who had put together the other lights wanted the ability to vary independently not only the light intensity of each of the two colors but also the frequency of the flash rate.

Hey look, as a design engineer looking for new ways to utilize light, LEDs, and state-of-the-art technology, I always try to cover all the bases to make people happy. This gives "electrical and operation foresight" in marketing a product. I figured someone might say, "well, XYZ company's model does this and yours doesn't so I'll buy from them." In this case, XYZ's company had a computer interface to vary the aforementioned parameters which I thought was great, but jacked the price high for those who would be serious enough to purchase such a light for it's exclusive purpose i.e. plant growth. I thought, "eliminate the computer, it's interface, but keep manual controls".

If I thought that 100 customers would want just a constant, fixed-intensity, light I'd be really happy as the design and construction and hence the price would be lower.

Bill Mack
[email protected]