budderlvr Modular LED Project

[budderlvr]

I am working on a new modular LED grow light. This thread will be a diary of my experience as I work through some of the many design problems.

Currently I am at the circuit design phase. Although I do not want to reveal too much of my design at this point I will provide some information that has guided my decisions.

The LEDs I will be using are from Lumiled. I am using the Luxeon K2s for the blue spectrum, and Luxeon IIIs for the red spectrum. The ratio of RED to BLUE (I will call this the R:B ratio from now on) is going to be 5:3 for the first board. This has more to do with cost than anything. Other threads get into more detailed discussions, but there no solid scientific evidence that I can see for any ratio - there are just too many unknown and variable factors at this time. My impression however is that BLUE LED light is at a part of the spectrum where the human eye is less sensitive. Actual luminous flux (SI unit is Lumen or lm) in BLUE LED light is deceiving because it may only be listed at say 23 lm on a datasheet, but that is corrected for the human eye - not the chemicals involved in photosynthesis (namely chlorophyll - look it up on Wikipedia). The third factor in choosing a 5:3 ratio is that RED light is more important in the flowering of the plant. More RED means more energy that the plant needs at flowering. I am totally open to comments or suggestions on this point in particular, as my science is sketchy at best.

As far as supply for each light module, the design will use a standard ATX power supply. Since this is a modular light, the wattage of the power supply is totally dependent on how many modules are used. I am hoping for a total power around 100 watts with 3 to 4 modules, and a light efficiency of about 80% of the power being used to produce light. To accomplish this, the design will incorporate LED driver circuitry for each color. This will also allow for future use of PWM drivers from a control circuit or computer which will be used to experiment on varying the ratio of RED and BLUE light.

I am by far no expert in lighting or growing. But I do have a strong electronics background and design circuits every day for my job.

Any input that you have, feel free to post it on this thread, but try to keep it relevant. Personal attacks should be done by IM.

Thanks for reading, and keep on toke'n. :rastasmoke:

budderlvr Reviewed by budderlvr on 08-25-2008. budderlvr Modular LED Project I am working on a new modular LED grow light. This thread will be a diary of my experience as I work through some of the many design problems. Currently I am at the circuit design phase. Although I do not want to reveal too much of my design at this point I will provide some information that has guided my decisions. The LEDs I will be using are from Lumiled. I am using the Luxeon K2s for the blue spectrum, and Luxeon IIIs for the red spectrum. The ratio of RED to BLUE (I will call Rating: 5

[painretreat]

Subscribed! I am at the edge of setting up and want LED's so bad! DB; WT have very interesting ones. Because I am cheap, I'd like to see cheaper, but may have to go that route, while waiting for the perfect LED and cooling system mix, as per your last post regarding matter in other thread! Thanks for doing this for us!:jointsmile:

[budderlvr]

Cheap is a ways away. My early projections would price each module around $75, so for an equivalent to the Procyon would be about $400 after you get a power supply and everything.

I have a hard time believing that heat will be a really big issue. I have a 650 watt power supply in my computer that is 85% efficient and it puts off very little heat. According to the datasheet on the K2s, they can be mounted on FR4 (regular PCB material, without metal core). The trick is using their pad design, coupled with a heat sink on the reverse side.

I am going to try digging around for some temperature info from other posters, perhaps someone could post their normalized heat sink temperature or the temperature of the metal core on their Luxeon Star.

[SunnyD]

?!?!?!?!?

Wow, all this talk of do it yourself LED boards has my brain twisted in a knot. Yikes, I'll try to watch this one if you would kindly put your process and materials in english, you don't have to, it would just make it super easy for all of us electrically challenged people out here.

:thumbsup:!!

[budderlvr]

SunnyD, this project is along the lines of an early commercial product. I am not going to get too technical because that would reveal my electronic design, which is not complete.

I do need to change one thing tho, the R:B ratio. I was hoping that the LED driver I selected would be able to drive enough current to run 5 RED, but that pushes things a bit too far. So I am going to drop it back to 4 RED Luxeon IIIs.

[veggii]

I am wondering why you are using the red Luxeon those are 635nm ??

[budderlvr]

veggi,

I picked the Luxeon III because it has a higher luminous flux than the K2, and they both have the same wavelength (and the same supplier - Future Electronics).

Would you recomend going with the LEDEngin red at 661nm? I am still trying to wrap my head around converting between lm and mw of Luminous Flux.

Since I have your attention, would you still recomend the K2 for the blue spectrum? Or has everyone gone to LedEngin?

Thanks for your post veggi! Made me rethink some things.

[budderlvr]

Okay, why even stack LEDs when you can buy 1 10w LED from LedEngin?
Now I am thinking about putting 1 BLUE LED (LZ1-10DB05) and 1 RED LED (LZ4-00R215, this is a 15w device).

Would it be okay to assume that the luminous power efficiency of the LedEngin High power lights is about 20%, meaning that 20% of the electrical power is converted into light energy?

Thanks again veggi, this is what has been bugging me since I started working on the controls for the Luxeon K2 and the Luxeon III.

Now I am thinking of just having 12v across each high power LED bank with space for a relay or transistor that I can add in the future.

EDIT: A lot of these devices are back ordered.

[Opie Yutts]

Would you recomend going with the LEDEngin red at 661nm?

Well I certainly would recommend 661 over 635, since it produces roughly double the chlorophyll activity.

Keep up the good work.

[veggii]

budlvlr it seem you might be miscalculating your red to blu ratio's/ approx 80% red / 20% blue yours seems close to a 50/50 ratio, am I reading your ratio correct??