Alright so here we go first diy cob build... So im going to hook up 5 parallel strings of 2 parallel cobs each on a cpu heatsink+fan using a single power supply(36v 11A) 5step up buck converters(one on each string for the leds) and one step down to run the 10 fans. List of equipment 10 CXA2530 5000k 3800lm ( 37v 800ma but will be run at 750ma) 10 heatsinks + fans 5 step-up ( 250w 10a (8.5 to 48v in) (12 to 50v out)) 1 step-down (36v to 12v) 6 electrical boxes (for buck converters) 1 36v 0-11A power supply(400w) power distribution block Thermal paste 25ft 18gauge tew wire Small metal bars to screw heatsink to So the cobs can take 1600ma max and need 37v at 800ma so i will run 5 strings of 2 at 1500ma using a stepup so if a cob goes out the other one wont burn. So if my math is right 10x750ma is 7.5a X 36v(270w) + 10 x (12v x ~120ma) (15w) my overall power would be about 285W. So power supply to distribution block will give me 6x 36v (5 with step up cc/cv and one with step down cc/cv) Then i will have 6 matching negatives paralleled to the same block going back to power supply. But for some reason this all sounds way too simple... am I missing something? Do I need some sort of a resistor or would the step-up unit include that? Do I need something between my -36v and -12v before they all go back to the power supply?
It doesn't look simple to me. It looks like a lot of work around to use a single power supply when it's probably much easier to just get a small separate one for fans. Not many people do that much parallel wiring with cobs. Most will get a driver that will run a reasonable amount like 6 or so in series and get a new driver for each 6 instead of using parallel strings to manipulate the voltage and current requirements. That said I'm not some kind of experienced cob builder. That's just what I've seen from my research.
Same here but getting a single power supply for a 36v cob would mean 10 cheaper power supplies or at least 2 very expensive good units and making series... but for a 36v power supply at 800ma they arent easy/cheap to get....
This way each stepup will block voltage/amperage for 2 leds just bellow max power for one cob to prevent burning them and total build cost will be under 200$ canadian for almost 300w and 40 000lumens of high power cree leds...
That's why you want a power supply with like a 120 volt output so it can cover 4 or so cobs in series. I was starting to dig around looking for a driver deal for you and then I realized, why are you building with these cobs? It's too much effort and they're not a better grow light. Get a 4 board qb120 set from amazon for $125 www.amazon.com/4x-QB120-Quantum-Boards-3000K/dp/B077KHMZTC/ref=sr_1_1?ie=UTF8&qid=1511641284&sr=8-1&keywords=qb120+quantum+board Get a meanwell HLG-240h-c-2100a from arrow for $57. https://www.arrow.com/en/products/hlg-240h-c2100a/mean-well-enterprises Make a perimeter frame to mount everything to. No heatsinks needed, no thermal paste, ect. About a 250 watt fixture but super efficient. 2.4umol/j leds.
Dang, even through Amazon? The other method is that those are Samsung LM 561c s6 diodes. They are being cranked out in strips and small pcbs in China for next to nothing. If you're electrically sound you can easily pick up strips from alibaba instead of those boards and get the same leds in the end. The Most Brightness 180lm/w Dc12v Samsung Lm561c S6 Chip Constant Current Hard Led Strip - Buy Hard Led Strip,Samsung Lm561c,Samsung Hard Led Strip Product on Alibaba.com
Those are week and cheap... I got 10 cree CXA2530-11A 5000k 3600 to 3900lm at 800ma for 75$, 36v 0-11a power supply 35$, wire 6$, 6plastic boxes 8$, 5 step-up 20$, 1 step-down 2$, distribution block 10$, heat sinks and fans salvaged, 5$ paste and 3.50$ coloured heat shrink wrap. So 165 canadian for 39 000 lumens and 300w of power
Those do 10,000 lumens with 60 watts roughly. The cree cxa2530 doesn't outperform those samsung leds. They may be a better deal but the 561c's win in lumens per watt. They are up to 200lm/w dimmed.
Well no they dont outperform but the alibaba leds i dont trust... samsung 100% but cant get em and im guessing i would be paying massive import/duties. Would love to get my hands on one 178lm/W at 111w for 19 647 Lm but would need an extra fan for high wattage but still looks sweet!!
Just a suggestion. I've built my own lights using driverless 50w cobs from Amazon. Connect direct to 120v. No extra power supplies. Mine are 1 warm white, 2 full spectrum and a 10w UV with a power supply all mounted to aluminum block that's been drilled for water cooling. Light stays around 90F and doesn't transfer heat to my grow. Getting results similar in growth to my old hps grow, but much better trich production. Sent from my XT1093 using Tapatalk
Everyone has been waiting to see someone doing well with those. I haven't seen it yet. Link some products and post some plant pics.
As requested Water cooled, Driverless COB closet grow My new thread, enjoy. Sent from my XT1093 using Tapatalk
Glad the driverless COB worked for you. Going to make a note that they are wildly dangerous for this application, especially next to water cooling. UL design requires them to be in a fireproof enclosure such as glass or 5VA plastic and given a non-conductive gap to any dead metal (your heat sink). Much safer using a UL class 2 power supply to a DC COB. It will also be more efficient.
I would like to make a nice enclosure. This was kinda a prototype to see if this would even work. The cobs are electrically isolated from the cooling block with thermal adhesive. I tried the lenses with them at first and was too much for my space limit. Couldn't raise the light high enough, was burning at like 2 ft away. Thought about a glass cover, but have read that you get significant light loss. I have heard that researchers have been doping glass with nanoparticles of gold to increase transmission, but kinda out of my reach. Sent from my XT1093 using Tapatalk
Exactly what ive been thinking of doing.. Good to hear feed back on it.. Might add some reds to a 3500K cob