DIY LED Basics

OCD Chilehead · Feb 24, 2016

I've been recently educating myself on DIY led builds. There have been a few members on here that have provided a wealth of information. Thanks a bunch. I found a 6 part, step by step video's that explain in detail. Thanks to growmau5 on YouTube. Thought I would pass this information on. It gave me a visual understanding of the builds. Enjoy! Sorry, I can't seem to figure out why the video's won't embed.

Basic COB and driver info part 1/6
https://m.youtube.com/watch?v=gYdN6d0v814

Common configurations for your grow space 2/6
https://m.youtube.com/watch?v=8fxcgF1FLCM

Choosing your heatsink 3/6
https://m.youtube.com/watch?v=iFj-FxIbCbg

Mounting leds/cob to heatsink 4/6
https://m.youtube.com/watch?v=elBzBTtE78I

Wiring led's/cob's to driver 5/6
https://m.youtube.com/watch?v=EULTIEf3fSI

Optics and dimming 6/6
https://m.youtube.com/watch?v=Jx0IigQkRYQ

grispa72 · Feb 26, 2016

Thanks for sharing!
I have seen these videos many times to fully understand all. I built my 500W COB Led lamp with cheap components taken on eBay spending less (a lot of less) money

Here
http://www.pepperfriends.com/forum/topic/14751-costruzione-modulo-cob-led/
the DIY guide. It is in Italian but there are many pics. I would like to do in english and share here on THP!

OCD Chilehead · Feb 26, 2016

grispa72 said:
Thanks for sharing!
I have seen these videos many times to fully understand all. I built my 500W COB Led lamp with cheap components taken on eBay spending less (a lot of less) money

Herehttp://www.pepperfriends.com/forum/topic/14751-costruzione-modulo-cob-led/
the DIY guide. It is in Italian but there are many pics. I would like to do in english and share here on THO!

That's great! Thanks for sharing here. I'm going to be purchasing my supplies soon. Will update with build.

Anyone else that want's to post pics or comments are welcome to do so.

Thanks again

Let's Try · Feb 27, 2016

Nice, Grispa.

What brand of COBs did you end up going with?

Let's Try · Feb 27, 2016

From my experience with COB LEDs so far, my main observation has been that you probably won't need as much light as you think you will. I started with 4x Cree CXB3590 running at 1.4 Amps and found that it was bleaching my poor little plants. I then dropped it down to 700mA and placed all 4 lights next to one another to cover just one shelf of plants, as I thought that cutting the power in half would mean I needed more lights together to provide sufficient light (the difference in intensity of light at 1.4A vs 700mA to my eye was huge). Wrong again - this was still too much.

I have since dropped down to 2 COBs per shelf at 700mA and my plants are growing much better now and look way healthier (they were a very light green before and have darkened up considerably since I made the switch). The efficiency of these things is fantastic, as the 4 of them are only using 100W altogether.

Bonus 1st basil harvest:

dragonsfire · Feb 27, 2016

Cool ! Thanks

grispa72 · Feb 27, 2016

Let said:
Nice, Grispa.

What brand of COBs did you end up going with?

The brand is Sodial, I found them on Amazon for 7,5. Each led has 100W power.

I use a different system to power them. I don't have a classic driver for led (they are very expensive).
I bought a main power supply (input 220V 50Hz AC - output 12V 40A DC) that feeds five boost converters, one converter per led. I can adjust the voltage and the current through two potentiometers on board. So you can fix volt and ampere. Each boost converter drives each led at 32V and 1.6A; this means a power of about 50W. So they run at half the power they can. It is already so much light.

If you want I can post the links to the led, the heatsink, the main power supply and the boost converter. Then I assembled all with two aluminium profiles and suspended through two chains.

It is an easy and cheap way to build a COB Led lamp.
Believe me, half the power is a lot lot of light.

Paolo

grispa72 · Feb 27, 2016

Let said:
From my experience with COB LEDs so far, my main observation has been that you probably won't need as much light as you think you will. I started with 4x Cree CXB3590 running at 1.4 Amps and found that it was bleaching my poor little plants. I then dropped it down to 700mA and placed all 4 lights next to one another to cover just one shelf of plants, as I thought that cutting the power in half would mean I needed more lights together to provide sufficient light (the difference in intensity of light at 1.4A vs 700mA to my eye was huge). Wrong again - this was still too much.

I have since dropped down to 2 COBs per shelf at 700mA and my plants are growing much better now and look way healthier (they were a very light green before and have darkened up considerably since I made the switch). The efficiency of these things is fantastic, as the 4 of them are only using 100W altogether.

Do you think that increasing the distance from the plants could be a solution leaving the power the same? You could decrease the power (that fall down with the square of distance) and gain lighted surface, if you have room, of course.

Let's Try · Feb 28, 2016

grispa72 said:
Do you think that increasing the distance from the plants could be a solution leaving the power the same? You could decrease the power (that fall down with the square of distance) and gain lighted surface, if you have room, of course.

That's a good idea. Never considered the gain on surface area.

grispa72 · Feb 28, 2016

Let said:
That's a good idea. Never considered the gain on surface area.

Yes, because if you consider the LED as the summit of the cone of light it is emitting, increasing the height (distance from the plants) means increasing the base area.

Let's go deeper with a numerical example. If you have a 90 degrees lens, the base area is = 2pi * h, where h is both the height of the cone and the base radius. This is because the half-opening of the cone is 45 degrees so the cone's height and the base's radius are square's sides. They are always the same if 90 degrees are constant.

If h is 10 the base area is 62.8
If h is 20 the base area is 125.6

We must remember that if you double the distance the power decreases by 4 times, so we have to optimize.

I hope you can understand. English is not my language...
In particular I don't know if I used the possessive case in the right way.

Paolo

OCD Chilehead · Mar 4, 2016

Ordered my Mean Well HLG-240H-C1750B. Ordered from Mouser. Estimated delivery is first part of May. Back ordered. It's ok. It'll give me time to get Cob's from Jerry and do some more research.

250.25W71-143V1750mA

Merchandise Total
USD $72.94
Shipping $7.99

grispa72 · Mar 5, 2016

This is my setup. It's essential and the cheapest I can build, but runs well!

I'll post the progress...

OCD Chilehead · Mar 5, 2016

That looks great. Thanks for sharing.

Scuba_Steve · Mar 5, 2016

Let's Try said:
From my experience with COB LEDs so far, my main observation has been that you probably won't need as much light as you think you will. I started with 4x Cree CXB3590 running at 1.4 Amps and found that it was bleaching my poor little plants. I then dropped it down to 700mA and placed all 4 lights next to one another to cover just one shelf of plants, as I thought that cutting the power in half would mean I needed more lights together to provide sufficient light (the difference in intensity of light at 1.4A vs 700mA to my eye was huge). Wrong again - this was still too much.

I have since dropped down to 2 COBs per shelf at 700mA and my plants are growing much better now and look way healthier (they were a very light green before and have darkened up considerably since I made the switch). The efficiency of these things is fantastic, as the 4 of them are only using 100W altogether.

Question... I just looked up these arrays you mentioned on the Cree website. It says they run at 2.4A - 3.6A for the 36V version, and 1.2A - 1.8A for the 72V version. Yet you mentioned that you were running them at 1.4A and then down to 0.7A. How is this possible? I assume your using the 36V model because you said they use 100W at 0.7A, which adds up about right.

Also, how big are your shelves?

Let's Try · Mar 5, 2016

Scuba_Steve said:
Question... I just looked up these arrays you mentioned on the Cree website. It says they run at 2.4A - 3.6A for the 36V version, and 1.2A - 1.8A for the 72V version. Yet you mentioned that you were running them at 1.4A and then down to 0.7A. How is this possible? I assume your using the 36V model because you said they use 100W at 0.7A, which adds up about right.

Also, how big are your shelves?

Hmm, I'm not sure where you're getting those numbers for current. Without looking at the data sheet, I'm guessing 3.6A is the absolute max you can run these at, and they wouldn't be overly efficient at that power. You can vary the current just about as much as you'd like, as long as you don't exceed that max, and as long as voltage remains fairly constant (voltage likely drops to 34 or 35 at the current I'm running these at). It's best not to take the current too low either for this reason.

My shelves are 16"x36". I actually just repotted a bunch of peppers from solo cups to smart pots this morning

grispa72 said:
Yes, because if you consider the LED as the summit of the cone of light it is emitting, increasing the height (distance from the plants) means increasing the base area.

Let's go deeper with a numerical example. If you have a 90 degrees lens, the base area is = 2pi * h, where h is both the height of the cone and the base radius. This is because the half-opening of the cone is 45 degrees so the cone's height and the base's radius are square's sides. They are always the same if 90 degrees are constant.

If h is 10 the base area is 62.8
If h is 20 the base area is 125.6

We must remember that if you double the distance the power decreases by 4 times, so we have to optimize.

I hope you can understand. English is not my language...
In particular I don't know if I used the possessive case in the right way.

Paolo

I definitely get it - your English is solid! Thanks for the write up.

Scuba_Steve · Mar 5, 2016

Let's Try said:
Hmm, I'm not sure where you're getting those numbers for current. Without looking at the data sheet, I'm guessing 3.6A is the absolute max you can run these at, and they wouldn't be overly efficient at that power. You can vary the current just about as much as you'd like, as long as you don't exceed that max, and as long as voltage remains fairly constant (voltage likely drops to 34 or 35 at the current I'm running these at). It's best not to take the current too low either for this reason.

My shelves are 16"x36". I actually just repotted a bunch of peppers from solo cups to smart pots this morning

I got that info HERE. I am not doubting what you are saying btw. I 100% believe what your doing is true. Just in my limited xp with LEDs, if you run too little amperage, eventually they just wont light up at all. Unlike an incandescent, where it will just burn extremely dim. And your number is waaaay under the datasheet minimum!

So in your experience, would you recommend a new builder to chose a smaller array? Maybe an equal number of CBX2530?

OCD Chilehead · Mar 17, 2016

grispa72 said:
This is my setup. It's essential and the cheapest I can build, but runs well!

I'll post the progress...

Went back through your diy link. I noticed your using the Arctic Alpine 64 plus's.

How are they? No problems?

I have four 64 plus's on the way. My Mean Well HLG-240H-C1750B should be shipped around the 28th of March. A lot sooner than expected delivery date of May. We shall see. I'm going with four 36v CXB3590's top bin. Just need to make up my damn mind on color, which is probably irrelevant for what I'm doing.

grispa72 · Mar 17, 2016

OCD Chilehead said:
Went back through your diy link. I noticed your using the Arctic Alpine 64 plus's.
How are they? No problems?
I have four 64 plus's on the way. My Mean Well HLG-240H-C1750B should be shipped around the 28th of March. A lot sooner than expected delivery date of May. We shall see. I'm going with four 36v CXB3590's top bin. Just need to make up my damn mind on color, which is probably irrelevant for what I'm doing.

Now, after few days it is running I can say Arctic Alpine 64 plus goes very well. I run my COBs half the power and they are almost at room temperature. The fan goes at the max speed and this is good for plants too: they grow stronger.

I made a mistake with color. I believed that 2700K and 6500K could mix together but it is not so. It's better going with one color 3500K or 4000K for a complete indoor season.

OCD Chilehead · Mar 18, 2016

grispa72 said:
Now, after few days it is running I can say Arctic Alpine 64 plus goes very well. I run my COBs half the power and they are almost at room temperature. The fan goes at the max speed and this is good for plants too: they grow stronger.
I made a mistake with color. I believed that 2700K and 6500K could mix together but it is not so. It's better going with one color 3500K or 4000K for a complete indoor season.

I'm going with the same color on all four lights. Color would be irrelevant to me, as long as they put out enough light for a given space. I'm seeing what is available right now.

I think your grow will do fine with what you've got. Looking at the photo, I can see against the wall, how the light overlaps each other. I would continue to see how it works before you change anything. I think you did a good job. I only hope my diy project comes out half as good.

Keep us posted on how it goes. Thanks for your input on the 64 plus's.

grispa72 · Mar 18, 2016

Following pics are my peppers, hydro lettuce and hydro basil under the COBs

This is a King Naga 7 days under COBs, before and after.

@OCD
I think you are right. COBs are so powerful that color is not an issue. 2700K are almost like HPS, to much toward red-spectrum, but very very powerful, so plants can grow very well. Cheaper than HPS, of course. If I must choose I go with 4000K in any case.