DIY LED red/white

Voidling · Jan 13, 2011

I wasn't intentionally super cropping and it had become two stems. I probably killed the growth tip with a dropped light. I happened to of taken a single clone and it had happened to of been from that plant, only reason I know it was a girl. The last of my seeds are going 12/12 to sex right away. Tired of wasting time on bagseed males.

Do you use deep blues 450nm peak, or another blue?

Deep reds are only for flower or do they help in veg as well? My current light is for veg only so just checking.

How many watts are you building for and how many square feet are you covering with it?

What driver are you using and where did you get it?

Thank you much

SupraSPL · Jan 13, 2011

Currently I am not using any blues but I have used 450nm Golden Dragons in the past and I have some of the same on order to retrofit the red/white lamps. Yes deep reds will help improve efficiency in veg but they should be used in combination with either standard 635nm reds or some other light source that provides that spectrum. KNNA explained that some strains do not do well when using only blue + 660nm.

The red/white lamp dissipates 157 watts and covers about 5 square feet. Of course you can use a much greater light density if you are limited on space but if you are aiming for max electrical efficiency this density is a reasonable goal. For veg I believe KNNA quoted 100 watts per meter2 but I will dig up that quote to be sure.

I use adjustable AC-DC constant current drivers that operate directly from AC mains. They typically run 85-90% efficient, cost about $19 and can drive 40-50 watts of LED dissipation depending on the vF of the string and the desired current. I got them from KNNA himself but they are available from a new online retailer in the US.

SupraSPL · Jan 13, 2011

Some useful and recent notes from KNNA about DIY LED light density:

"As default, Im using 275-300W/m2 for blooming. Actually, its possible to get very good results using less (as low as 200W/m2, but that is for pros, with experience, green finger and mostly, selected genetics. If not, dont use less than 250W/m2).

But on small cabs people often use 450W/m2 and higher, looking for max production of space.

On the other hand, for veg, Im recommending 100W/m2 (low growth rate required, moms maintenance when too much cuttings are not required), 120W/m2 (default, work fine on most situations), up to 150W/m2 (fast grow rate, vegging large plants)"

...

Installed watts required are strongly dependent of the efficiency of LEDs used. For most commercial lamps out there, you need to use 360W, yes. But any of them use top bins. Their efficiency is from 25-50% lower than top bins and LEDs we are talking about . Thus wattage you need to use is higher on same percentage.

Anyway,I usually talk about minimum light required to achieve plants bud fine. Its possible to use up to double of minimum and get fatter colas. There is a wide margin before reaching excessive light densities."

Voidling · Jan 13, 2011

Thanks.

Just making sure since the leds say deep blue instead of just blue as is talked about in the forum. 635nm is standard red and 660nm is far red? I thought 660nm was standard red as those were the only golden dragons listed from KNNA on that site for sale. I'm reading from so many different places in chunks at a time I'm getting confused. Sleep deprivation isn't helping.

My build is only 28in x 18in so I don't need near that much coverage. I plan to build it out in 3 or 4 panels for adjustability and to spread the cost out over time. Really wish I could over build my veg light but that's just not going to happen.

It's probably the same driver I'm looking at.

Thanks.

Edit:
I was writing while you were. I'll have to figure out the w/m2 to w/in2 I guess so I can make sense of it. I'm talking about building my own with the top bin that I can get from Knna.

So for Flower
1 square meter is equal to 1,550 square inches. So 300W/1550 square inches.

27"*18"= 486 square inches

300W (x)W
1550in2 486in2

solve for x and I get 94W. So 24 or 32 watts per panel depending on if I do 3 or 4 panels.

Mother/clone/veg

150W (x)W
1550in2 360in2

35Watts for 150W/m2 and 46 for 200W/m2. I don't think I'd be hitting the 35 with the 23 leds I'd planned on getting.

How do you count the watts of a string of leds?

Thanks

sm0k4 · Jan 13, 2011

SupraSPL said:
The red/white lamp dissipates 157 watts and covers about 5 square feet. Of course you can use a much greater light density if you are limited on space but if you are aiming for max electrical efficiency this density is a reasonable goal. For veg I believe KNNA quoted 100 watts per meter2 but I will dig up that quote to be sure.

Yes, I believe 100 was about right. Then for flower you would want 260-300 W/m2. I think I'm going for 360 W/m2 maximum with my 3x2 flower cab. Should be nice and expensive

But mostly it will run around 300 unless I boost currents to 600mA.

I did boost my PC light to 630 mA and am still running it. 25.5 dissipation watts now and the cab is now running at 83-85 degrees Fahrenheit. Think I got my situation dialed in.

sm0k4 · Jan 13, 2011

SupraSPL said:
Installed watts required are strongly dependent of the efficiency of LEDs used. For most commercial lamps out there, you need to use 360W, yes. But any of them use top bins. Their efficiency is from 25-50% lower than top bins and LEDs we are talking about . Thus wattage you need to use is higher on same percentage.

This is the most misunderstood concept with LED lighting and why the hyped market is in rough shape when it comes to product reviews. These light makers have no idea they are using crappy LEDs that only emit 10-15% of the energy as light. Even with the best LED on the market it is lucky to give off 50% of its energy as light. I'm not sure the exact value, but its ballpark 50%, KNNA would know.

Using high quality top bins results in better light density with less LEDs involved due to them running more efficient and not wasting energy as heat, thus giving off more luminous output per watt. Not sure how the photons are involved in all this, I've not studied the subject enough yet, but I'll get there.

So this is why commercial lights will never equal an HPS with half the wattage unless they use the best available bins they can get. But that would cut into profit margins now wouldn't it?

sm0k4 · Jan 13, 2011

Voidling said:
Thanks.

Just making sure since the leds say deep blue instead of just blue as is talked about in the forum. 635nm is standard red and 660nm is far red? I thought 660nm was standard red as those were the only golden dragons listed from KNNA on that site for sale. I'm reading from so many different places in chunks at a time I'm getting confused. Sleep deprivation isn't helping.

My build is only 28in x 18in so I don't need near that much coverage. I plan to build it out in 3 or 4 panels for adjustability and to spread the cost out over time. Really wish I could over build my veg light but that's just not going to happen.

It's probably the same driver I'm looking at.

Thanks.

Edit:
I was writing while you were. I'll have to figure out the w/m2 to w/in2 I guess so I can make sense of it. I'm talking about building my own with the top bin that I can get from Knna.

So for Flower
1 square meter is equal to 1,550 square inches. So 300W/1550 square inches.

27"*18"= 486 square inches

300W (x)W
1550in2 486in2

solve for x and I get 94W. So 24 or 32 watts per panel depending on if I do 3 or 4 panels.

Mother/clone/veg

150W (x)W
1550in2 360in2

35Watts for 150W/m2 and 46 for 200W/m2. I don't think I'd be hitting the 35 with the 23 leds I'd planned on getting.

How do you count the watts of a string of leds?

Thanks

660nm is actually deep or hyper red. Far red is between 700-800nm and getting into IR spectra. Its usually good to supplement with 635s also since 660s can't really hit the lower red wavelengths. I went by a 50/50 ratio of 635s/660s and this might change in my later designs.

I tried ot not copy someone else's exact ratio in order to compare results. The more of us that play around with ratios and designs, the quicker we can rule out what does and doesn't work.

KNNA only sells LEDs he finds efficient and worth growing with. Osram does make a 635nm red LED, part # LR W5AM. But for cost/Watt, KNovas are cheaper and efficient.

Yes, only the deep blue is needed. The wavelength is actually a bell curve so it will deliver a good output from 440-460nm. All that is needed, 475nm blue is kind of redundant if you use whites.

power = volts * amps

On the datasheet there will be a current vs. voltage graph. Take any current value and through the graph get the voltage value. Multiply them to get your output in watts.

Voidling · Jan 13, 2011

Thanks Sm0k4. Lots of good stuff there. What is your ambient temp outside of your cab?
Thanks

Edit: To get voltage is just adding all the forward voltages correct?

I don't have much money coming in and a lot has already gone into my cab, so at this point I need something at least fairly close to something I know will give good results. Also being first cab grow, first mj grow, ect... I don't need more variables you know. Plus I got to get my outdoor cold boxes and greenhouse built as well.

I updated my build thread with my first step with pictures.

sm0k4 · Jan 13, 2011

Voidling said:
Thanks Sm0k4. Lots of good stuff there. What is your ambient temp outside of your cab?
Thanks

Edit: To get voltage is just adding all the forward voltages correct?

I don't have much money coming in and a lot has already gone into my cab, so at this point I need something at least fairly close to something I know will give good results. Also being first cab grow, first mj grow, ect... I don't need more variables you know. Plus I got to get my outdoor cold boxes and greenhouse built as well.

I updated my build thread with my first step with pictures.

Ambient temp outside the cab is 72ish, give or take. I did put my cab in the closet recently and it jumped a few degrees, but still at 83-85 in the cab. If I redesign the carbon filter to be less restricting on the exhaust, I will be able to drop them below 80 I'm sure. Carbon design is another hurdle for me since I've never had to use one before.

Yes, just add up the forward voltages in the string and that will be your total voltage you need on the driver output. Or take your driver output voltage and start subtracting.

Say you have a 25 volt, 60 Watt driver and you have 16 LEDs. After some math, you split up the 16 into two strings of 8. Each string comes out to roughly 20 Volts at .5A. This would be 10 Watts per string. So you can use 4-5 of these size strings on that driver since power in parallel is added.

The real world application also shows very similar voltages. The Osrams are pretty much spot on to what their datasheet says. My actual power came out to be just slightly higher than my calculated power. I attributed that to my interpretation of the graph in the datasheet.

I get why you just want to build something that works. I'm just a tinkerer so I suggested it as a thought. Just keep your ratios as Supra/KNNA suggested. KNNA has a collective of people all experimenting with his light builds, so I would take his advice as a solid place to start.

I'm in the same boat. Got my bigger cab on hold until I move and figure out what I can spend. Might be a delay until I can build it, so I will be flowering a couple bagseeds I just germinated with my PC cab. I have a thread started in the Micro Grow section. Not really gonna go all out with it, just a pictorial progression thread to highlight how the LEDs are working in there. My beans should break soil today hopefully. Kinda sad just looking at brown dirt in cups right now.

Voidling · Jan 14, 2011

Thank you for the information.

I'll have to find the spec sheets for the leds and figure that out when I'm not so out of it.

I need to kill off my males or get my cab done with carbon filter asap as the smell is getting noticable. I put some seeds into coco two days ago after a 24 hour soak. Hope to see some pop soon myself.

blimblom · Jan 16, 2011

here is my heatsink ready to accept KNNAs LEDs (KNNAaaaa do you hear meeee, lol lol)

just some 2m alu profile cut in 55cm spread out evenly every 3cm, the concept is to have enough space in between for the air to circulate (my extraction fan is over the leds). I plan to put some 77watt worth of LEDs on them and its for the flowering room. For the Vegging room I will be using PC heatsinks, after SupraSPLs suggestion

Voidling · Jan 17, 2011

Where do you get aluminum like that and how much does it go for? I'm trying to figure out how to do mine so I don't have to pay shipping on heavy metal items.
thanks

blimblom · Jan 17, 2011

Voidling said:
Where do you get aluminum like that and how much does it go for? I'm trying to figure out how to do mine so I don't have to pay shipping on heavy metal items.
thanks

It is aluminum profile (usually for windows) 2,5mm thickness, you can find it in hardware stores . This one had 2,2m length so I cut it down to 55cm, and drill holes for the screws to fit in.

The cost of the profile was about 12euro. Not as good and elegant as the heatsinks of SupraSPL but much cheaper and easier to find.

Voidling · Jan 17, 2011

Yeah, money is my crunch right now. Spent too much on my pl-l lights and ballasts that put off too much heat. I'll have to find that equation Knna put out for determining heat load or capacity of a piece of aluminum to see how much I'd need.

SupraSPL · Jan 19, 2011

The formula with the newest batch of bins is about 100cm2/dissipation watt. To evaluate any heatsink calculate the perimeter (profile side) of the heatsink then assume we are multiplying by a 1cm (or inch) section.

Voidling · Jan 19, 2011

Did I read in Knna's thread that you calculate both sides of the aluminum so it'd be the perimeter times 2 or did I misunderstand that?
Thanks

sm0k4 · Jan 19, 2011

Voidling said:
Did I read in Knna's thread that you calculate both sides of the aluminum so it'd be the perimeter times 2 or did I misunderstand that?
Thanks

You mean area? For the fins yes. He was just simplifying the equation by multiplying by 2 instead of adding the area again.

This is why finned heat sinks cool so much better. Way more surface area to work with which does more to assist the cooling process.

Voidling · Jan 20, 2011

Yeah I know finned works better, but its also more expensive.

Yeah, mean area. Was trying to understand Supra's post on it.

Thanks

budlover123 · Jan 20, 2011

sm0k4 said:
...Yes, only the deep blue is needed. The wavelength is actually a bell curve so it will deliver a good output from 440-460nm. All that is needed, 475nm blue is kind of redundant if you use whites....

I guess that depends on the white, I was just looking up these Cree X-RE LEDs and the cool, neutral, and warm white all had blue almost entirely in 440-460nm range according to the data sheets not much in the 475 range, I would love to do a side by side scientific test with a bunch of blue and maybe even cyan LEDs vs royal blue vs all of them together done, but I don't have $600 to test that one out. Who says they don't work? Even LEDgirl over there is talking about green LEDs I though I heard, white leds have red. green and blue, thats not very redundant. I think it could be more easily said that using separate red, green, and blue lights to make white is redundant

SupraSPL · Jan 21, 2011

Calculating the perimeter is easier than it seems. Measure and add up the distance around the entire profile and that's it. Once you have that number you can figure out how many cm of heatsink to cut to get a given amount of surface area. Assume that 100cm2 is needed for each dissipation watt (for passive cooling)

For example this heatsink has a perimeter of 26.94 inches so if you chop a 1 inch length you get 26.94 in2 of surface area.

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