DiY LED - Cree CXA3070

darkbug said:
i was going to go with 2700k for veg and flower. I was thinking of going 5k for a separate veg tent but I dont know yet.

Yea the 3070 isn't that much more at all.

I was planning on mounting each led to its own cpu heatsink and using a wall wart to power the fans. I haven't purchased anything yet.
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I've been crunching numbers between the cxa3070 and the vero line using Supra's efficiency numbers to try and get a fair comparison. It seems to me that Cree wins out if your target is 35% efficient and Bridgelux wins if your target is 30% efficient (cost per efficient watt of output). I guess you'd tend to go with efficiency if worried about heat or power costs when choosing.
 
SupraSPL said:
@GU420 yep COBs operate the same way as any other LED except they have a high vF. Drivers don't have to break the bank though. You can run a single CXA3070 on a $6 driver. I tested one and it worked great, ran at 648mA and 88% efficient with a perfect power factor. There is also a 1A $11 and 1.6A $11 both should work with the CXA3070. I don't have any to test but they are similar construction as the $6 driver and they all claim 87-88% efficient which turned out to be accurate.

I also tested the CXA3070 on this $6 12V DC driver hooked to a car battery, it worked great, ran at 646mA.
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Supra - I trust you're correct on the drivers linked being viable, but how do you know when a driver rated for 30-36V will work for a LED rated at 38.5V? I'm just trying to learn.
 
You make an important point. At 650mA my 3070 has a vF of 34.5 but at 1.4A it will be ~37. The reason I expect those drivers to work is because my 650mA version operates up to ~50vF. The current decreases to ~600mA when you push that hard and reliability might decrease as well because components are running hotter.

Some drivers have circuitry that will refuse to be driven past a certain vF but the ones that do not will just decrease current output. There is a chance that the 1.6A drivers are set up that way so I plan on ordering one and will give it a thorough testing.
 
caretak3r said:
Cree wins out if your target is 35% efficient and Bridgelux wins if your target is 30% efficient (cost per efficient watt of output)
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That is a good insight.

The difference in those numbers may not seem like a lot but it means that the Cree is 16.7% more efficient, which will pay for itself very quickly.
 
Thanks to the COBs I am up to 500W of diy LED and have been able to phase out a pair of 600 HPS. Seriously considering scrapping another pair of 600 HPS and going to 1000W diy LED. Half COBs half R/W/B. Removing the HPS has also allowed me to reduce the fan speed in the carbon filters saving some power and it is so much quieter which I really appreciate.

Got the final numbers from the last round (364g). Best yield I have had in awhile and that was with 7 ladies instead of the normal 8 so there is room for improvement. The dankness was truly top notch had to change my carbon ahead of schedule. Will get some dry bud pics up.
 
Took some more measurements now that they are installed. 6 modules total 300W in this tent. I never realized how handy an accurate infrared thermometer could be. Incoming air is 19.5C, ambient inside tent is 20C, in between heatsink fins is 24C. Leaves directly under the COBs are 21C. I turned off the COBs and as soon as they were off took the temp of the surface and got 32C.

I will kick on the HPS tomorrow which will increase ambient temp and will radiate heat directly into heatsinks but if anything it will be a good thing because I think plants are a bit on the cool side.
 
This looks extremely promising. After reading CREE's press release I searched for the CXA3590s too with no luck. Seems like most places say these have a 1-year backorder.

Supra,

I'm a complete noob, but really interested in mimicking this type design since it looks fairly straight forward and efficient. Once you've got it all sussed out, do you think you could make a how-to for newbies like myself? I'm no engineer but am pretty good with a soldering iron.

Also what did the BOM end up costing you?
 
Hey supra do you clean the LED in any way? After mine have been hanging I see dust on the emitting part from a 90degree angle. Just wondering if they are able to be cleaned
 
Thanks for link. Those 3590's are on a phased dimmer would
intrigue the masses!
QUOTE=Abiqua;10142255]Yes! Awesome Supra....I think I found some on Octopart....maybe,

http://octopart.com/partsearch#!?q=cxa 3590 3590's that is......

Granted, Digikey was only selling them in 1000 piece lots but I think Arrow or Verical may have a few in stock, good luck.[/QUOTE]
 
CXA3590-0000-000R00CD0E3

Seems to be the only one in stock. This runs at 5000k.

Maybe not enough red for flower?
 
Cococola36 said:
Hey Supra, sorry if i missed it, whats your thoughts on using a secondary lens or reflector on these types of leds? I found these http://www.ebay.com/itm/360691007100
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My strategy has been to keep the modules in tight on the canopy and adjust them upward as the plants grow. Lenses can be useful if you have lots of vertical space, but my vertical space is limited ~6.5 feet. Also lenses, diffusers and protective covers penalize the efficiency of all the photons emitted very significantly so if they can be avoided they should.

Reflectors on the other hand are a great idea. They will redirect some of the stray photons that would have been useless otherwise without penalizing the photons that do not need to be redirected. Reflectors are simple enough that you can make your own with no need for precision. Any cone shaped object painted flat white will work and you can customize with what angle works best for your situation.
 
Gaius said:
This looks extremely promising. After reading CREE's press release I searched for the CXA3590s too with no luck. Seems like most places say these have a 1-year backorder.

Supra,

I'm a complete noob, but really interested in mimicking this type design since it looks fairly straight forward and efficient. Once you've got it all sussed out, do you think you could make a how-to for newbies like myself? I'm no engineer but am pretty good with a soldering iron.

Also what did the BOM end up costing you?
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Sure thing, if you can run an iron you can build a sweet lamp. I think it is a great idea to make a simplified guide to make it more accessible.

Bill of materials for a 50W 42.6% efficient lamp something along these lines:
CXA3070 X 2 = $82
Heatsink 10.08" X 6" X 2.8" = $43 ($171 shipped for 4, heatsink USA)
700mA driver X 2 = $24

Misc materials:
Prolimatech PK3 or similar (eBay)
Kapton tape (eBay)
Zinc chain (Walmart or Amazon)
50V hookup wire for LED string 18ga (or use 600V wire from old xmas lights) (elecdirect)
600V wire for AC connections 18ga (elecdirect)
slide connectors .25" (bare, crimp on) (elecdirect.com)
heatshrink tubing .25" (elecdirect.com)
Solder 63/37 lead (amazon)
Solder flux gel syringe - MG chemicals ($10 eBay/Amazon) (this really helps)

tools needed:
cordless drill (harbor freight $15)
heavy duty crimper/cutter/stripper (walmart ebay amazon)
soldering iron (60w eBay $10)

recommended:
GFCI (eBay $7)
sand paper to lap heatsink surface (3M home depot)
 
So you are passively cooling these? THose are the big boys from HSUSA, even though they might only be 6" long, that is cool!

Thank you for the list, going to put that into my notes for later reference! :peace:
 
Abiqua said:
Yes! Awesome Supra....I think I found some on Octopart
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Thnx abiqua I will give Newark a call ASAP because I was about order a bunch of 3070s. If I can get the CXA3590-0000-000R00BD30F and run it at 350mA it will cost me an extra $275 but would be 14% more efficient which would pay for itself in a week. They would dissipate 24W each and run at 48.3% efficient.
 
CannaBare said:
Hey supra do you clean the LED in any way? After mine have been hanging I see dust on the emitting part from a 90degree angle. Just wondering if they are able to be cleaned
Click to expand...

Yes I noticed they pick up dust and particles very easily. I kind of wack them with a lint free cloth rather than wipe them. That might be something we will have to do regularly.

The compressed air idea might work well but of course it is not actually air in there it is fluorocarbons. May also may leave a residue from the bitterant on the LED and the buds.
 
mtnstream said:
Thanks for link. Those 3590's are on a phased dimmer would
intrigue the masses!
Click to expand...

Dimming could be extremely useful. We could decrease the output during the first few weeks of flowering and increase it as we spread the plants out and the canopy grows wider and deeper. Maybe dim during the last week also?

KNNA once pointed out that when it comes to growing lamps, the best kind of dimmer is an adjustment to the actual drive current of the constant current driver. Dimmers that cycle the led on and off cause the led to suffer from current droop during the on cycle. It does achieve the goal of dimming but not as efficient of a method especially for long term use. That is as far as my knowledge goes, how would a phased dimmer operate?
 
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