Designing an LED grow light

[necros]

I've been researching this on and off for some time now. The light pattern detailed here is specifically designed for my Rubbermaid grow, but I think the general design could be used for others.



It's split into four modules, each for one plant. However the LEDs were laid out considering they will be used together as one large light. The list of different LEDs are as follows:

10 700 nm
100 660 nm
25 645 nm
10 500 nm
10 470 nm
10 450-560 nm (white)
10 450 nm
10 430 nm
10 405 nm

I probably would have purchased more orange and less red, but it was a matter of economics, the reds were really cheap. The frequencies chosen were based on research I did over the past month. The main chart that got me started on this whole thing was from High Times issue Sept 09 page 67 (I retyped the info):



I've also purchased some 735 nm LEDs to experiment with Photoperiodism, a phenomenon a came across while researching this. In this article they were able to cut the dark time to trigger flowering in C0ckleburs by two hours using 730 nm light. I'm wondering if it would be possible to increase the amount of light time the plants get during flowering to increase yield.

I'm putting this all out there now because I haven't built the lights yet and thought it would be a good time to solicit advice to avoid any potential mistakes or perhaps find better ways of doing this. I'm planning on using breadboard and resisters b0fin style.

Also I thought there's some good information in that high times chart, that information needs to get out there.

[Hatch]

Looks Like You Are Off To Great Start, I See You Have Been Following The_BOfin, Did You Caught In His Latest Designs He Has Added Some UV-Emitters That He Feels Really Helps The Trich Developement..
Well, I Wish You The Best Of Luck, Wishes & Karma On Your Project, Can't Wait To See It Come Together For Ya..

[Michael]

That was a great article, man... thanks for the link!

Like Hatch, I also wish you the very best and I'll be following closely.

This should be a very interesting project.

[necros]

Yes I read about the UV additions, that's a future addition! :D

He also started to get into the hi-tech hi-output LEDs which I don't have the time or resources for right now (heatsinks, special power supplies, etc.). These are all 5mm LEDs which appeal to me because I can get very close to the exact frequencies.

[ileso]

will be watching very closely

[Hatch]

That Sounds Like A Great Plan, You Will Do Fine With Starting With The LEDs You Have, Like You Said You Can Always Add Later..Yes He Has Laid Down Some Serious Cash On All The LED's & Stuff He Has Built & Been Researching,,I Wish I Could Get Him To Come Over Here, But He Hasn't Had Time To Be On Much At All At The Present.

[necros]

Thank you google cache for saving this post, here's an edited copy/paste of the google cached version:

Originally posted 08-27-2009, 01:55 PM

LEDs are starting to arrive. The 450's are on backorder so I'm not going to have them, the 430's, and the 645's for three to four weeks. That gives me time to think about resistors and how I'm going connect them together.

This is a link from b0fin's thread that has been so very valuable as I'm not electrically inclined (I can solder though!):

LED series/parallel array wizard

I can't find my old volt meter and soldering iron so I have to purchase those as well. Since I don't know exactly how many volts my power supply is putting out until I get my meter (I'm guessing it's actually around 13 or 13.5 volts) I did an example wiring schematic using 12 volts.



I'm probably going to put the side 660 ones on one array as well instead of seperate like this diagram. I'm visually oriented so putting together that diagram really helped me visualize how all this gets soldered together.

Like I said, I'm not electrically inclined so if someone who is can double check my approach on the resistors I'd appreciate it! Here's the spec sheets on all of the LEDs as well as the specifications that the array wizard is looking for that I chose to make my resistor calculations with:

LED --------diode forward voltage ------- -diode forward current (mA)

700 nm ---------------2 ----------------------------10
660 nm ------------- 1.7 ---------------------------30
645 nm -------------- 2 ----------------------------50
500 nm --------------3.2 ---------------------------30
470 nm --------------3.5 ---------------------------20
450-560 nm --------- 3.4 ---------------------------30
450 nm --------------3.3 ---------------------------50
430 nm --------------3.8 ---------------------------30
405 nm --------------3.7 ---------------------------30

[Michael]

We switched servers and lost a few days of posts in the transition. We apologize for the inconvenience. But, we are on a much faster, more secure server now.

[necros]

Finished fabricatng the first module. It's a frankenstien, the one I learned on and made my mistakes on. But it works. The next three should look a lot better.

In general I'm happy with the output of the LEDs. They all have a very narrow beam. The last picture shows the coverage on my ceiling with the module 1.8 meters away. The spot is probably about one meter in size.

[Michael]

Nice.

[Zigzagman]

Way to go necros. Can't wait to see your baby in action, congratulations...

[I8ntLucky_UR]

Well done I agree. It looks complicated probably not for everyone to do but way to go.

Just a thought from a guy (me) that doesn't know much at all about LED's. The board you are using to mount the LED's (the brown one with the tiny holes) could you cover that with anything more reflective of do LED's reflect the same as HID's or CFL's? Does that board get hot at all? Could you use Mylar film over it and do you think it would make any difference?

Again, good on you for getting that up and running and I can't wait to see it in action. How so is that btw?

[necros]

You're right Lucky, it's really complicated and time consuming. For whatever it's worth, I was 100% stoned the whole time I was fabricating it!

I'll be the first person to say go buy one and save yourself the hassle. My problem is a product like this does not exist yet (high light output, thin, small, low heat, 12 volts dc). So I'm the type of person that tries to make it happen.

If you know of a product that I can use to make the boards shiney-er let me know. I think mylar is too thick though. In my tests the board doesn't get hot at all.

It's not up and running yet, I still need to fabricate three more of these LED modules (200 LEDs total) and install it along with some fans in my grow box. Hoping to get it done this weekend but it's a lot of work. I've got four little girls waiting for me to complete the work so they can start flowering.

[I8ntLucky_UR]

Hi and thanks for the quick response. Could you paint a coat of matte white before you mounted the LED's? If you used a latex base it would not clog the little mounting holes.

I find this fascinating I'm not a techno self making type but it looks like fun all the same. And if the cost savings is there plus getting a better range why not right?

You said "dc" is this running on batteries or is there a converter somewhere between the plug in the wall and these lights?

[necros]

I'm running a 12 volt dc power supply, 4.2 amps. I'm hoping it will be enough for four of these LED modules, three fans, and four 30cm T5s.

The LED light is very directional, meaning there's only a very narrow band (around 15°) of light coming out of each one of them, kind of like a wide beam laser. I've totally avoided looking directly at them because when I did I saw serious spots for about five minutes.

Because they are so directional I think making the boards reflective is a low priority. I'm just trying to make sure they work at this point!

[necros]

The second module has a lot of improvements since I kind of know what I'm doing now! I'm going to use this one as a model for the last two.

Like I said before these things are really bright. You can't tell from the picture since the beams are so focused and narrow. I can't look directly at the light without seeing spots, I have to check the LEDs with my peripheral vision when I'm building them.

It has the same number of LEDs but it looks like more since they are spaced evenly. I don't think I'm going to try to duplicate the patterns laid out in the first post because it would be a mass of crisscrossing wires. I've seen protoboards like that, I think I'm just trying to keep things tidy since these are going into a grow box. If I could design a trace board and have it fabricated, that would be the way to go but I think it would cost too much.

I kept all of the resistors on the rear this time so it looks a little neater on the LED side.

The main hurdle with these is power management. This one worked really well because it has power around the outside (LED side, two sides positive, two negative) and running down the middle length-wise (rear, two postive, two negative). At that point it's just like stringing Christmas lights.

After I finish the other two and install them into the grow box along with the new fans I'll post pictures to my grow box thread.

[LED astray]

Use a program called Eagle to design a circuit diagram, it is an easy point and click interface, it can then design the layout of the copper tracks for the PCB (Printed Circuit Board) automatically, some touchups may be needed but are easy to do.

There are companies that can then take the PCB file and etch and drill the board for you and they are happy to deal with hobbyists as long as you provide the Eagle file unless you want to pay an arm and a leg for them to design the pattern.

They have generic board sizes and charge based on the whole board no matter how many patterns are on it so fit as many patterns onto the board as possible and you can then cut them apart with a hacksaw or band saw.
I think they may even cut the board down to the individual patterns if you want but charge more.

You can choose the thickness of the board and the copper, how many layers of copper (single sided, double sided, multi layer like PC motherboards) and whether you want through hole plating where the copper goes through whatever holes that you choose to connect the track on one side of the board to the track on the other (or between multiple layers) so your issue with criss crossed wires won't be a problem.
You could save a bit of money by doing this the older way with a pin made from a cut off component leg or some solid core copper wire.

You can have component layout markings silk screened on any side, you can have the board coated in varnish or enamel to prevent corrosion.
You can choose different board materials like fibreglass, phenolic, epoxy etc.

They will happily sell you just one board or as many as you want, 10, 100, 1000+.

circuit board manufacturers - Google Search

Get the professional look and quality without ordering thousands of boards.

[necros]

Very useful info LED astry, I have some research to do!

The free version of Eagle only supports 100 x 80 mm boards and the retail price is out of my budget range so I'll have to figure something out there. Perhaps use smaller boards.

I'll probably finish this particular project on my current path since I need these done very soon. I do need a clone / veg cab though so perhaps that will be version 2!

[Shpongled]

Hey thanks for the great info. I would love to work with some people around here to design and test some custom LED lighting systems. I am a decent electronics hobbyist and am working on my own design. You info is great and I will be looking forward to making my own.

Now for a few questions. Have you found any decent 1w leds at a reasonable price point? Some of the norlux hex modules look great but are expensive. I dont know if its better to have more lower cost LEDs or less higher quality ones.

If a decent design could be flushed out it would be nice to have a small run of pcb's made up for those wanting to give it a try. This is similar to what I have seen on some custom audio forums. It is really fun buying a pre-made PCB and following a writeup and parts list to make something that might otherwise be out of your skill level. I have tooled around with Eagle but am not very good.

I would be willing to put in the work creating all of the parts lists and tutorials though. I can pm you a great write up I did for an amplifier build as an example of the type of guide I want to make. I would post it here but there is a bit too much personal info on there for this forum.

I made my own post in this forum with some basic info of what I want to do. Please feel free to put some ideas down.

Peace

[necros]

Hi Shpongled,

I'm happy with all of the LED choices I made except for the Radio Shack 700 nm which I replaced with an epitex. I averaged $1.00 per LED (200 LEDs total). Some were in the $3-$5 per LED range but the 660 nm's were cheap so I saved there.

I think the only way to know for sure which choice is better is to build and test (grow). Check out that b0fin link, he started using the big ones and the top cola's would always start pointing tword them!

If you come up with a PCB design using the above components or similar pass it on! I haven't had time to build or look into eagle and designing PCBs.