Cree DIY COB LED? Why do people use white lights?

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flexy123

Well-Known Member
Ever since I started with my two MarsHydro 300W grow lights (which I am very pleased with) I got very interested in that entire grow light/LED technology. Spectrums, LED ratios, different types of LEDs, the usual.

I am getting increasingly interested in DIY and I came across several threads on various places on the net.

I am especially interested in COB lights.

So I found some threads on the internetwebs where people recommend, say those 10x10 CREE Cree CXA3070 LEDs.

A typical lamp would be like this:

cree1.jpg


Basically mounting the LED to a heatsink, fan, get a driver...and that's it. (All that I can easily do).
There are even DIY kits available

My question is about the LEDs in particular. People say they are incredibly good and effective, especially the CREE. But those LEDS are white!

For me as coming from a grow light with RED/BLUE and some WHITE this is odd. Doesn't this mean that a lot of energy is wasted on the green spectrum? Why are people having good results with those white LEDs?

Would it be better to go with COB that has "full spectrum" reds and blues and some whites or is the white light really "better" for growing?
 
flexy123 said:
Ever since I started with my two MarsHydro 300W grow lights (which I am very pleased with) I got very interested in that entire grow light/LED technology. Spectrums, LED ratios, different types of LEDs, the usual.

I am getting increasingly interested in DIY and I came across several threads on various places on the net.

I am especially interested in COB lights.

So I found some threads on the internetwebs where people recommend, say those 10x10 CREE Cree CXA3070 LEDs.

My question is about the LEDs in particular. People say they are incredibly good and effective, especially the CREE. But those LEDS are white!

For me as coming from a grow light with RED/BLUE and some WHITE this is odd. Doesn't this mean that a lot of energy is wasted on the green spectrum? Why are people having good results with those white LEDs?

Would it be better to go with COB that has "full spectrum" reds and blues and some whites or is the white light really "better" for growing?
Click to expand...
Yes because LES Cob have a higher CRI then Blurple
 
The reason people are having success with the cree 3070's COB's is because they have a high Par value despite having the added white/green spectrum's.

The white/greens turn into a bonus light spectrum that makes it as complete as a light source as a HPS or MH bulb for instance.

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I have four 100w 400-840nm full spectrum chips on order , after that build I plan on building a few 100w cree 3070 cob's (bin CB)
The CB bin has the highest luen output of all the 3070's.
With twice the output compared to the lowest bin 3070 it cost *twice* as much as the low bin cob's although the added lumen's more then make up for the added expense.

They are not to be underestimated ! they may well be the best grow COB available and its easy enough to test :MoreNutes:
so far people are really liking the CREE 3070 , I will test those pesky 100w full spectrum cob's out and see first hand.


I currently have four Mars panels and felt the need for some side lighting so I bought the cobs.
 
LEDBud said:
The reason people are having success with the cree 3070's COB's is because they have a high Par value despite having the added white/green spectrum's.

The white/greens turn into a bonus light spectrum that makes it as complete as a light source as a HPS or MH bulb for instance.

`````````````````````````````
I have four 100w 400-840nm full spectrum chips on order , after that build I plan on building a few 100w cree 3070 cob's (bin CB)
The CB bin has the highest luen output of all the 3070's.
With twice the output compared to the lowest bin 3070 it cost *twice* as much as the low bin cob's although the added lumen's more then make up for the added expense.

They are not to be underestimated ! they may well be the best grow COB available and its easy enough to test :MoreNutes:
so far people are really liking the CREE 3070 , I will test those pesky 100w full spectrum cob's out and see first hand.


I currently have four Mars panels and felt the need for some side lighting so I bought the cobs.
Click to expand...

If you have any tutorials on how to build COB LED lights I would be very grateful. These sound like exactly what Im looking for, but if its insanely complicated I will pass. Plmk. Thanks!
 
Building is definitely the way to go ! :thumb:

COBS, 150W draw, home made power supply, home made cooling system

the grow is just getting started, I will be sharing how the white LEDs do.

IMG-20151123-01582.jpg


Vlad
 
Their super simple to make and as easy as a DIY as installing a CPU in a computer.

I bought 80mm heatsink Fan combo's to mount the Cobs on. One side of the Cob is + the other side is - and the fan gets its own power supply.

I am using a 650w computer power supply wired to step up boost converters to power each of he Cobs.


I will start a thread and post a link in my signature when they arrive.
Not 100% sure if im going to JB weld them to the heatsink or not but I'm leaning that way as its a super secure way to mount them.
Normally you would Drill & Tap the heatsink use screws and the common heatsink paste , I like the sounds of JB weld much better.

If down the road a Cob goes south on me I could knock it off the heatsink with a hammer and screwdriver.

Frenchfries said:
If you have any tutorials on how to build COB LED lights I would be very grateful. These sound like exactly what Im looking for, but if its insanely complicated I will pass. Plmk. Thanks!
Click to expand...
 
Cree CXB and Bridgelux Vero 3000K,4000K,5000K contain the spectrum your looking for depending on application. 3000K is High Reds/Low Blues and replace High Pressure Sodium, 4000K is High Reds/High Blues and replace HPS/MH Full Cycle, 5000K is Low Reds/High Blues and replace Metal Halide for vegetation applications.
I believe in using Dimmable 100watt CXB3590s and 120watt Vero29 to power down on hot days/veg/early flower and power up during mid to late flower for penetration
COBs have made it much easier for growers to service there own fixtures also. To me that's the biggest benefit of this tech.
 
Don't use the JB weld, it is crap and I will share with you why :

The thermal resistance of JB is high, you need a product with nano technology or silver content.

I use arctic silver, the same stuff they use on CPUs.

Yea it sucks, but the proper way to mount those expensive, high powered COBs is to tap yourself a threaded hole to accept small machined screws and then dollop some fine paste on the chip (less is more) and then crank down the screws. LEDs like to be squeezed to their aluminum substrates to stay cool. Glue does not achieve that by far.

If you want to run your COB at max rated power and achieve 50000 hours, you need good thermal interface material.

Vlad
 
There are vids on youtube by two guys in particular, very smart on the diy set ups. I switched to diy cobs about 8 months ago and I will tell you with out a doubt, they cree cobs are the way to go. I have 4 fixtures, 16 cxb3070, 4 hlg 185 1400 drivers with individual heatsink/fan combos. My best run, dwc, one plant....887 grams....21 grams short of 2 pounds. I run 1/2 the electricity, 1/2 the ac to cool my tents and they will bury a 1000w hps. Do t use the cxa, they take 42 watts to fire up, the cxb is only 36 so you can run 4 cxb on a 185 and only 3 cxa. Also, do t use jb weld, you will blow the cob right off your heat sink.
 
I plan to use JB Weld after all the Cob's are cheap and I do not plan on being a Nancy with them:volcano-smiley:

My plan is to drill the heatsink use self tapping screws along with the JB Weld to bond the COB to the heatsink.
They will succumb to my wishes.

There are some CPU temperature test videos online that compare JB Weld vs Arctic Silver that show a difference of 3 degrees between the two. Its nothing new.

*IF* I was to use a purpose made heatsink adhesive I would use the 2 part arctic silver epoxy
I personally would NOT trust a 1 part CPU heatsink grease or paste on my COB's as it dries out in a few years

I know this as I have replaced many CPU's and fixed some with overheating issues. Heatsink grease is temporary.

Perhaps some others have experience with the heatsink grease drying out as well , I could use the back up right about now.. haha.

I think my paste disagreement should be considered

Happy Wake n Bake ;) peeps
 
2 piece expox imo , will do just fine used it for years buildin 'high-end PC's
but if i build it'll be hardscrew' down type mount with artic silver/reg
just to make the heat sinks swappable If &/when the COB tech changes
took my 3 small 400 mars appart to clean & next summer time I strip the housings off them & make a single array outta them
pretty simple construction imo looks easy I'm hooked
 
Zombiewoof said:
2 piece expox imo , will do just fine used it for years buildin 'high-end PC's
but if i build it'll be hardscrew' down type mount with artic silver/reg
just to make the heat sinks swappable If &/when the COB tech changes
took my 3 small 400 mars appart to clean & next summer time I strip the housings off them & make a single array outta them
pretty simple construction imo looks easy I'm hooked
Click to expand...

I watched someone turn their old Mars II 400 into a 5 piece COB light on Youtube earlier today.
 
I watched a DIY type video on the lower Bin 80 CRI CXB 3070 Cob's earlier today and they seem like a good choice.

I found info that states the higher priced CB Bin Cob's are not really better then a lower Bin / cri COB's for growing.
The 80 CRI Cob's are apparently great and much cheaper then the 90 or 90 CRI CB bin Cob's.

According to test taken the 80 cri cobs have a wider red band
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My updated plan is to buy the 50% cheaper 80 CRI 3070 Cobs
 
I'm new to LED grow lights and I guess what I am asking is, what are the negatives of the type of unit where you can use any type of individual gu10 style bulbs. Would it work decently? If so why not...
 
LEDBud said:
I watched a DIY type video on the lower Bin 80 CRI CXB 3070 Cob's earlier today and they seem like a good choice.

I found info that states the higher priced CB Bin Cob's are not really better then a lower Bin / cri COB's for growing.
The 80 CRI Cob's are apparently great and much cheaper then the 90 or 90 CRI CB bin Cob's.

According to test taken the 80 cri cobs have a wider red band
````````````````````````````````````````````

My updated plan is to buy the 50% cheaper 80 CRI 3070 Cobs
Click to expand...

ya got a p/n ? I got the cree pdf CBX chart I don't understand which one you refer to I've yet to watch that GG vid so bare with me

I got post concussive syndrome , math is out but can do a recipe & can hack all day long in my garage
 
Excellent DIY setup going there !!

Keep us posted about your grow with the Cree 3070s. I am curious about these too.
A 10x array of these could really be interesting for a larger grow!! IF you are going to use epoxy, for & others attempting this, PLEASE... use Thermal (aluminum/or silver based) epoxy.

Arctic silver thermal epoxy is the best to use for perma-mounting high output LEDs onto a heatsink.

Just having these metal on metal will not provide enough thermal transfer, this will likely lead to the LED overheating.

Arctic Silver Thermal Adhesive
 
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