Any concise posts/guides on DIY Cree COB?

I've done just enough research to see the benefits of DIY. I'll continue researching, but was wondering if someone can offer a recommended list of items for something that pulls 600w or less, good for a 4x4 tent? Seems there'd be a popular DIY kit post that lists popular items and where to buy. Kindly post if there is..

A general starting point that you can scale up

(4) Cree CXB3590 3500K CD 36V (email Jerry [email protected])
(4) Ideal COB Holders 50-2303CR
(4) Lenses/reflectors
(1) Mean Well HLG-185H-C1400
(1) HeatsinkUSA 3.5"X40"
(1) 80mm fan
(1) 12V fan PSU

~212W power draw, 196 dissipation W, 56.3% efficient, 110 PAR W. A pair of those in a 4X4 would give you 12.4 PAR W/ft² or 620 PPFD. 3 of them would give you 18.6 PAR W/ft² or 925 PPFD (dim as needed)

That configuration allows you to put the driver on board for an all in one unit, without using a case. Many other options, some DIYers use separate CPU coolers, some use wider heatsinks and stagger the COBs. Some put the drivers on a separate board. Either way, I think 4 CXB3590s with an HLG-185H driver is a good value and reference point.

Could you run this setup on the 5.8 heatsink passively ?E="SupraSPL, post: 11990810, member: 129132"]A general starting point that you can scale up

(4) Cree CXB3590 3500K CD 36V (email Jerry [email protected])
(4) Ideal COB Holders 50-2303CR
(4) Lenses/reflectors
(1) Mean Well HLG-185H-C1400
(1) HeatsinkUSA 3.5"X40"
(1) 80mm fan
(1) 12V fan PSU

~212W power draw, 196 dissipation W, 56.3% efficient, 110 PAR W. A pair of those in a 4X4 would give you 12.4 PAR W/ft² or 620 PPFD. 3 of them would give you 18.6 PAR W/ft² or 925 PPFD (dim as needed)

That configuration allows you to put the driver on board for an all in one unit, without using a case. Many other options, some DIYers use separate CPU coolers, some use wider heatsinks and stagger the COBs. Some put the drivers on a separate board. Either way, I think 4 CXB3590s with an HLG-185H driver is a good value and reference point.[/QUOTE]
Couls

Yes, the 5.886 or whatever is the passive version of that build. You would probably want at least 36" of heatsink - I run 40 inches plus for each 4 COBS or 200Watts and they are cool to the touch.

So 42" of 5.886 can handle 200 watts?

Per supra

@ 56.3%
(4) CXB3590 3500K CD 36V @ 1.4A (49W ea) $190
(1) HLG-185H-C1400 $65
196 dissipation W -> 85.7W heat ->
passive cooled heatsink 10284cm² -> 5.88" X 38" heatsink $72 (could split in 2 to improve uniformity/spread)
or
active cooled heatsink 3428cm² min -> 3.5"X36" heatsink (for spread) $45 +80mm fan +psu $10
(4) lenses $16
110.3 PAR W covering 6ft² = 824 PPFD
$311 = $3.07/PAR W passive cooled (great value point IMO, very efficient use of driver)
$326 = 2.96/PAR W active cooled

Even 36" seems to be a little overkill, but a heatsink is something your going to likely keep between upgrades. A cooler COB is a more efficient and longer lasting COB, so its best to keep 9" on the 5.886 profile for each COB being run like this.ventilation you have in the tent would make these semi active - and a very safe bet.

Thanks!

Those COB holders are great. A couple questions on those specifically. What's the preferred method for adhering to a heatsink, drilling a hole and screwing in using a good thermal grease, or Arctic Adhesive? Connecting wiring, are there any kind of standard clips that can be used, or just solder?

The ideal COB holders are push style connectors for your wires. I think they support 16GA-18GA wire? 14 was a very tight fit for mine, next time I'm going 16GA.

The ideal COB holders have two holes that are meant for screws, it's M3 screws I think - the safe route is to carefully measure out your holes and drill/tap (use cutting oil and back out frequently). The 5.886" profile allows you to drill and tap up to an M5 or M6 screw without touching a fin - so with an M3 screw you have a bit bit of slack for imperfections.

Artic silver or similar compound are preferred over using any of the pads.

Wire everything in correctly (supra has a post on how to power) and remember if your sitting your driver on your heatsink you NEED to ground the heatsink/driver. If driver is mounted remotely - just ground the driver.

I think I'm going to put 2 cobs on 5.8X18 heat sink, spacing the cobs 12" apart. I think that gives me the best chance to fill any area with one cob a square foot.

Great info Doc thanks much!

I'm planning to have an 8'x4'x~8' (starting out with 4x4). For now I am getting 16 3500k CD w/ 185-c1400a. Should I, as suggested, split the heatsink and get (2)5.88x19" for 4 cobs?

I saw somebody post an image with 2 of the 19" heatsinks with cobs placed on the opposite sides of the heatsink (see image below).
Is this the most optimal cob placement (Doc stated at least 9" apart)? Would I need to follow the same pattern if I were to use a 38" heatsink? Does it matter if they are so close to the edges?
And last question; would lenses/reflectors be recommended if there is going be decent amount of non-occupied space around the plants (there will be mylar on the walls).

Hope I'm not driving anybody crazy with noobie questions

SupraSPL said:

A general starting point that you can scale up

(4) Cree CXB3590 3500K CD 36V (email Jerry [email protected])
(4) Ideal COB Holders 50-2303CR
(4) Lenses/reflectors
(1) Mean Well HLG-185H-C1400
(1) HeatsinkUSA 3.5"X40"
(1) 80mm fan
(1) 12V fan PSU

~212W power draw, 196 dissipation W, 56.3% efficient, 110 PAR W. A pair of those in a 4X4 would give you 12.4 PAR W/ft² or 620 PPFD. 3 of them would give you 18.6 PAR W/ft² or 925 PPFD (dim as needed)

That configuration allows you to put the driver on board for an all in one unit, without using a case. Many other options, some DIYers use separate CPU coolers, some use wider heatsinks and stagger the COBs. Some put the drivers on a separate board. Either way, I think 4 CXB3590s with an HLG-185H driver is a good value and reference point.

Click to expand...

Hey Supra, thanks for this. How do you calculate the area that something like this would cover?

CesarEl said:

I'm planning to have an 8'x4'x~8' (starting out with 4x4). For now I am getting 16 3500k CD w/ 185-c1400a. Should I, as suggested, split the heatsink and get (2)5.88x19" for 4 cobs?

I saw somebody post an image with 2 of the 19" heatsinks with cobs placed on the opposite sides of the heatsink (see image below).View attachment 3550870
Is this the most optimal cob placement (Doc stated at least 9" apart)? Would I need to follow the same pattern if I were to use a 38" heatsink? Does it matter if they are so close to the edges?
And last question; would lenses/reflectors be recommended if there is going be decent amount of non-occupied space around the plants (there will be mylar on the walls).

Hope I'm not driving anybody crazy with noobie questions

Click to expand...

If you've got the room you want to give 2-3 inches of heatsink on all sides of the COB. I'm not sure placing them near the corners would provide better cooling than lining them up in the middle. Heat spreads rapidly through aluminum so unless you were using a couple cooling fans I don't see the placement being a big deal.

DIYGrow420 said:

Hey Supra, thanks for this. How do you calculate the area that something like this would cover?

Click to expand...

If you pack more of them into a given area you will increase light intensity (PPFD) or if you use less and spread them out you will get less PPFD. So if you have a general idea what you want your PPFD to be and what space you will be covering, you can figure how many lamps to pack in.

SupraSPL said:

If you pack more of them into a given area you will increase light intensity (PPFD) or if you use less and spread them out you will get less PPFD. So if you have a general idea what you want your PPFD to be and what space you will be covering, you can figure how many lamps to pack in.

Click to expand...

Ok. So if I said that I was going to use cxb3590's in a quad array, any other factors you can choose, in a 2x2 and a 2x4 with a PPFD between 700-800. How would one do the math for that?

So if you put (4) CXB3590s @ 50W ea in a 2X2, I would estimate ~25 PAR W/ft² or 12601PPFD.

200 dissipation W * .563 efficiency = 122.6 * .9 lens/reflector/wall losses = 101.3 PAR W
101.3/4 ft² = 25.3 PAR W/ft²
25.3 * 4.65 * 10.7 = 1261 PPFD averaged

If you put that same lamp in a 2X4 you would get 630 PPFD averaged

Supra you are the man. This all makes 100x more sense now. Thanks.

Thanks for the information Rahz.

So ultimately this is what i'm looking at with my final set up (see image below).

I'm curious is there really no difference between having the cobs alternate their position (#1) and having them just be in a straight line (#2). Doesn't #2 have more space between each cob?

Is there any other more efficient way to place the cobs? Maybe I should invest in a slightly bigger heatsink?

Thanks again
-K