COBs for PC Grow

Hi Guys/Girls,

So i have finally decided to dive into the world of cobs. In my part of the world no one knows what COBs are so most lighting suppliers do not keep them. Ordering from mouser or digikey will be extremely expensive for me (exchange rate) so this is not an option. I have found ONE supplier from where i can order.

I will be growing in a PC 1-2 plants max.
I need one light for veg+flower.

I do not know much about leds except what i have read on various forums. I might have narrowed down my choice to the CXA2530 4000k. I am stuck on which option to get. I am not sure about the binnings and what it means.

Is the CXA2530 a good choice?
What cri should i choose?
Is 4000k sufficient for a full cycle grow light?

Can you guys just confirm if this would be the right choice for my requirements? or if not, any recommendations?

I plan to order from here:
http://www.trxe.com/search.php?searchTerm=CXA2530&resultCount=10&searchNew=Search&startingRecord=0&displayCount=10

Whats the secret to getting a reply on this forum?

Q9550 said:

Whats the secret to getting a reply on this forum?

Click to expand...

patience is the key to get a response.. I know nothing about COB's but someone will and will help you out.

good luck brother or sister.

Hey Strocat,

Thanks for the reply lol

I actually forgot about this thread until today.
I managed to come up with a solution to my LED requirements:

3x CXA2530 4000k U2 Bin http://www.trxe.com/search.php?searchTerm=CXA2530-0000-000N00U20E5&resultCount=10&searchPrevious=Prev&startingRecord=0&displayCount=1
3x 300mA Fasttech drivers https://www.fasttech.com/products/1739207
3x Intel FanSinks http://www.frostytech.com/articleimages/200706/intelC2Dstock_pspc.jpg

So 3 CXAs @ 300mA=
5410lm
173.3lm/w
31watts

No problems, you can use 2700k - 6500k to flower/veg but it just makes the plant grow differently

Personally I'd go for a CLU048-1212 kind of build as they're $12us a COB for similar performance

CLU048-1212 @ 300ma:
- 1869lm
- 33.1v
- 9.9w
- 188lm/w

@ 700ma
- 4208lm
- 34.6v
- 24.2w
- 174lm/w

Have a chat to @CobKits and have a look through his site @ CobKits.com
I'm sure he'll be able to help you out - even with international shipping

@Millsie I did have a look at CobKits even posted in his thread, post was ignored, very nice offerings unfortunately shipping to my location is expensive and also quite long if using cheaper methods (60 days+-) and then customs slaps on their charges.
Also its quite impossible in my country to get any other COB besides the CREEs and that too are only available in a few varieties and they are EXTREMELY expensive sometimes double the price that any other country would pay.
All these factors are currently hindering my progress with this COB build.

Eg. CXA3590-0000-000R00AD27F
At mouser for $40.80
Local Supplier: $51.32

So basically i'm limited to a build that uses only CXA2530s due to them being cost effective.

Yep... use what you can get easy and cheaply (but not too cheap).
Well Buck You Too
You haven't given an actual space dimensions, I had 3 CXA1507s running at 350mA inside a server shell at 24" high.
The plant liked it in there, but never tried to flower under them (plus that build was too noisy).

You are using larger Cobs, heatsinks, etc at 300mA (36v x .3A = 10.8 watts) about 10 watts (5 or 6 of which is heat).
Mine were 12.8 watt and the little heatsinks worked fine as long as fan was running on them (the noise problem).

Too bad those drivers don't come in a 1A to 1.5A version, especially at that price.
Hope to see a build...

You might get a better response in the Stealth/Micro/Cab Growing forum. It's right next to this one in the Main Forum menu.

@HalfBee
Thanks for the advise. The dimensions of the case are:
L=40cm
H=35cm
D=19cm
1.29 sq.ft

I agree with the not too cheap statement. You get what you pay for after all.
I actually have a 9U server cab that i wanted to convert to a grow box, maybe thats going to be my next project.
The FanSinks were salvaged from old PCs, i have 3 of them but they 3 different ones.
At 10 watts im pretty sure the heatsinks should cope without the fans but the grow doesnt need to be stealthy so will run them anyway.
Do you have any pics of your trees under the CXA1507s? I had a quick look at my local supplier and they do stock them.

If i get 4 of them: (CXA1507s 36v 4000k 75CRI H4 @ $3e)
@250maA
5202.2lm
140.9lm/w
37watts

Would that be a better build then the CXA2530s?
Quick question, how is LED efficiency calculated?
Like when people say the cxa2530 driven at 300mA is 50% efficient for example....

Would be mighty interested to see you fit that in there. However, at 300mA, you probably won't get shit. Grow with 7th gen Vero29Cs using 1400-1670mA, in a closet.

I don't understand small microgrows like that. Use a closet, good COBs, a plant or two, and you'll impress even yourself.

Q9550 said:

Hey Strocat,

Thanks for the reply lol

I actually forgot about this thread until today.
I managed to come up with a solution to my LED requirements:

3x CXA2530 4000k U2 Bin http://www.trxe.com/search.php?searchTerm=CXA2530-0000-000N00U20E5&resultCount=10&searchPrevious=Prev&startingRecord=0&displayCount=1
3x 300mA Fasttech drivers https://www.fasttech.com/products/1739207
3x Intel FanSinks http://www.frostytech.com/articleimages/200706/intelC2Dstock_pspc.jpg

So 3 CXAs @ 300mA=
5410lm
173.3lm/w
31watts

Click to expand...

Stop using watts and lumens, that shit's useless in deternining grow power. PPFD, PPF, and PAR watt efficiency is where it's at. I get huge, healthy plants using only 241w of light, equivalent to 600w of HPS.

Olive Drab Green said:

Would be mighty interested to see you fit that in there. However, at 300mA, you probably won't get shit. Grow with 7th gen Vero29Cs using 1400-1670mA, in a closet.

I don't understand small microgrows like that. Use a closet, good COBs, a plant or two, and you'll impress even yourself.

Click to expand...

Thanks for the suggestion, but if you read through the entire thread you would see my limitations:
Cost of COBS
Availability of COBS

Currently CREEs are the only cobs available to me and the CXA2530s was proving to be the best and cheapest cobs that are available which is why i went with them.
I dont have space to do a closet grow which is why i went with PC and i am planning on converting a server rack to a grow box soon.
My aim is to grow 1 plant to harvest, weather the harvest is 5grams or a 100grams, doesnt matter to me im in it for the FUN of it.
I get bud for cheap where i am so the grow is really just an hobby for me.

Q9550 said:

Thanks for the suggestion, but if you read through the entire thread you would see my limitations:
Cost of COBS
Availability of COBS

Currently CREEs are the only cobs available to me and the CXA2530s was proving to be the best and cheapest cobs that are available which is why i went with them.
I dont have space to do a closet grow which is why i went with PC and i am planning on converting a server rack to a grow box soon.
My aim is to grow 1 plant to harvest, weather the harvest is 5grams or a 100grams, doesnt matter to me im in it for the FUN of it.
I get bud for cheap where i am so the grow is really just an hobby for me.

Click to expand...

You should at least look into running it harder. Trying to help you, bud.

Always appreciate the help buddy #AllOpinionsMatter

If you could give me a bit more information that would help me understand why i should run it harder? What would be the benefits?
Being inexperienced with leds means that i have no idea how to derive PPFD,PPF and PAR values. Lumens is all i have lol and im going off 5000lm per sqft
The configuration i went with was designed by another member in another forum. His recommendation was 4 x CXA2530s @ 300mA each.
I went 3 due to cost. He also mentioned that driving them at that current would make them over 50% efficient and running them harder would possibly cause light bleaching due to the height restriction of the PC.

Maybe you have another recommendation for me for 1 plant in 1sqft?

Q9550 said:

Always appreciate the help buddy #AllOpinionsMatter

If you could give me a bit more information that would help me understand why i should run it harder? What would be the benefits?
Being inexperienced with leds means that i have no idea how to derive PPFD,PPF and PAR values. Lumens is all i have lol and im going off 5000lm per sqft
The configuration i went with was designed by another member in another forum. His recommendation was 4 x CXA2530s @ 300mA each.
I went 3 due to cost. He also mentioned that driving them at that current would make them over 50% efficient and running them harder would possibly cause light bleaching due to the height restriction of the PC.

Maybe you have another recommendation for me for 1 plant in 1sqft?

Click to expand...

Nope. Maybe it's better it's driven softer like that. I'm more worried about it stretching if it doesn't have enough light.

PPFD is your Photosynthetic Photon Flux Density. Plants don't use lumens, they use photons within the PAR range. 950-1100 is a 600w HPS (I put that out with about 241 of COB.)

The 2530s are better if you can get them. The light surface is larger and they put out more light.
I used 'cheapest available' for 1507s and paid more for the holders than the Cobs cost.
Am doing an under desk veg area with Vero 13s gen7 5000K running at 350mA.
Is a 24 inch high area and still prop plants up 6 inches closer to lights since running so soft.
-- Still in experimental stage on plant positioning for veg

But running those 2530s on proper heatsinks at 1000mA would light most closet spaces well.
Start small if you must, upgrade when you can, enjoy the journey.

HalfBee said:

The 2530s are better if you can get them. The light surface is larger and they put out more light.
I used 'cheapest available' for 1507s and paid more for the holders than the Cobs cost.
Am doing an under desk veg area with Vero 13s gen7 5000K running at 350mA.
Is a 24 inch high area and still prop plants up 6 inches closer to lights since running so soft.
-- Still in experimental stage on plant positioning for veg

But running those 2530s on proper heatsinks at 1000mA would light most closet spaces well.
Start small if you must, upgrade when you can, enjoy the journey.

Click to expand...

Oh, hey! There you are again!

@Olive Drab Green I can always prop up the plants to get them closer to the light thus reducing the stretch but once mounted the leds wont be able to move in the case. Maybe i'll do one run with the 300mA drivers and see how it goes and how bad the stretch will be then i can consider getting more powerful drivers.

@HalfBee Yeah i plant to upgrade in future once i get a few more grows under my belt. At least in future all i'll need is the drivers to up the lights. I eventually would like to get a grow tent but a long while from now. Baby steps...

The COBs were delivered to me today. I received 2 still waiting on 1 more + drivers from fasttech.
Pics soon...

So a few pics of the intended build:
I was quite surprised to find out that the COBs came from Mouser




Would this be an option, 2 COBS 1 SINK

Hi All,

So finally i received the drivers... Well almost, just have to pick them up from the post office.
Im finding myself in a bit of a dilemma. I plan on mounting the cobs using molex holders but my drill decides that it doesnt want to work anymore so drilling and tapping is going to be an issue. I will have access to a drill tap in a month or so but i cant wait that long to get them up and running.
My next option is to use adhesive thermal pads and solder the leds but im not a fan of soldering and dont want to go this route and risk damaging the cob surface.
So while on the meds i came up with a plan, just need to know from the experts if it would work out or should i just wait for the drill press....
I will fit the cobs to the molex holders and then mount them to the heatsinks using thermal grease and kapton tape...? Would this work?