Here's what I recently made with some cheap parts off Ebay. Bout 40 dollars in parts for this set-up. (2) 50 watt chips on this one. Just waiting for the PC fan to come.
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LED FAQ) Building and DIY
- Thread starter Dion
- Start date
Best to use the 100W chips, they are almost the same price as the 50watt ones, but they have 100 LEDs in them instead of 50, and they put out more light per watt. I drive the 100W chips at 10-25Watts no more or they get too hot.
It's best to order the drivers and LEDs separately on eBay, what the seller will typically do is bundle a 50W LED with a 50W driver and that is bad, the LEDs don't work properly if you try to drive them flat out. If you pull apart one of those LED outdoor Chinese floodlights, you will see for example, at 30W one has a 30W driver in it, but the LED is rated at 50 or 60W. They need headroom, or the heat will dramatically shorten their life, plus wast a lot of electricity.
Inside the Chinese COBs, they are a matrix of 1W LED chips in columns of 10, wired in series to get them up to around 36volts. Then they put the columns of 10 in parallel which shares the current. The 20W ones will have 2 x columns of 10LEDs, the 50W 5 x columns of 10LEDS, etc. up to the 100W which has 10 x columns of 10 LEDs.
I wouldn't drive them at more than 150mA per LED chip, so in the big 100 LED version you have 10 columns in parallel which means 10 x 150mA or 1,500mA = 50W. Even that is a very high considering how cheap the things are on eBay, you could almost totally cover the heatsink in the photo with 8 of them (4 x wired in parallel on each driver) to get the max light distribution, and run them nice and low power eg. 12.5W each.
Remember, the goal is to cover as much of the grow without shadows, if you run a single COB or two, you will have way more shadows than if you run a matrix of the things at the same total power.
It's best to order the drivers and LEDs separately on eBay, what the seller will typically do is bundle a 50W LED with a 50W driver and that is bad, the LEDs don't work properly if you try to drive them flat out. If you pull apart one of those LED outdoor Chinese floodlights, you will see for example, at 30W one has a 30W driver in it, but the LED is rated at 50 or 60W. They need headroom, or the heat will dramatically shorten their life, plus wast a lot of electricity.
Inside the Chinese COBs, they are a matrix of 1W LED chips in columns of 10, wired in series to get them up to around 36volts. Then they put the columns of 10 in parallel which shares the current. The 20W ones will have 2 x columns of 10LEDs, the 50W 5 x columns of 10LEDS, etc. up to the 100W which has 10 x columns of 10 LEDs.
I wouldn't drive them at more than 150mA per LED chip, so in the big 100 LED version you have 10 columns in parallel which means 10 x 150mA or 1,500mA = 50W. Even that is a very high considering how cheap the things are on eBay, you could almost totally cover the heatsink in the photo with 8 of them (4 x wired in parallel on each driver) to get the max light distribution, and run them nice and low power eg. 12.5W each.
Remember, the goal is to cover as much of the grow without shadows, if you run a single COB or two, you will have way more shadows than if you run a matrix of the things at the same total power.
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Dion, I'm looking at individual drivers on the 'baba, and I don't know what shipping costs. I see a few nice dimmable 1050ma 40V drivers at good prices but I don't know what the actual cost would be. What has your experience been, and do you have any good tips on a source or brand for a driver that size?
I am not Dion but here is one option: http://www.aliexpress.com/item/High...220225468.html?spm=2114.13010608.0.125.f9jMnm
Free shipping.
Rilla.
Interesting..have you looked at the CREE 3590's?
I just looked some up on Ebay. Once I get some extra money saved I will look into getting some of them .
You can buy a dozen of the 100W Chinese COBs on eBay for the price of one CXB3590. The main choice comes down to your electricity cost, the Chinese COBs will use a lot more power to get the same lumens out as a CXB3590, but the CXB wont spread those lumens across the canopy as evenly as a dozens Chinese COBs will.
A Chinese 100W driver to run a bunch of COBs is only $10, a fraction of the cost of a 100W MW. So small growers can set themselves up quite nicely of DIY eBay parts.
People are still growing with CFL! The cheap Chinese LEDs are way better than that.
Dion
Active member
perfect, so you have a 10k pot? and a 100k resistor?
yes you will dim that driver down to around 60% mostly, plan on running around 150w with 4 cobs and like i said that light would work for a space twice ur size for future growth
congrats
Dion
Active member
i don't know much about dali but when i looked into it seemed a bit unecisarilrily complicated for our applications, id rather use a controller for that
check aliexpress not alibaba
i only buy with free shipping, shipping is china post, takes 2-4 weeks
http://www.aliexpress.com/item/CE-C...60.html?spm=2114.13010208.99999999.317.iXMSyY
http://www.aliexpress.com/item/1Pcs...34.html?spm=2114.13010208.99999999.336.iXMSyY
http://www.aliexpress.com/item/Free...45.html?spm=2114.13010208.99999999.435.iXMSyY
http://www.aliexpress.com/item/Free...53.html?spm=2114.13010208.99999999.518.iXMSyY
You make a good point on the cost Arf, but I would rather spend the money upfront and build a fixture once than constantly pull it to replace or repair cheap Chinese LEDS as they burn up.
To each their own - some folks like tinkering and constantly working on a light rig/engine/etc. I just want to build it and have it working reliably so I can concentrate on growing the best plants I can.....but that's just my point of view.
They don't just burn up, you obviously haven't tried them. They are quite reliable at the wattage I suggest which is 10-20W for a 100W COB, they are set and forget. Only failures I have had is one 20Watt driver that died after about 15hours use. Not worth sending back at under $2.
I don't use the 20W drivers anymore I just put several COBs on a 50W or 100W which are $6 and $9 respectively
jikko77
Active member
a mix of:
cxb 3590, 3000°k and 5000°k, 70 and 90 cri
cxb 3070, 3000°k can't remeber if 80 or 90 cri
about 400w max @ 1400mA.
this holder was way easier to install.
better than the one used for the 3070.
the work isn't finished yet, still need some more money to get it sorted.
i've in mind a couple of idea, add a couple of more cob, then mono and and uv cfl or in alternative another string of 5 cob
cxb 3590, 3000°k and 5000°k, 70 and 90 cri
cxb 3070, 3000°k can't remeber if 80 or 90 cri
about 400w max @ 1400mA.
this holder was way easier to install.
better than the one used for the 3070.
the work isn't finished yet, still need some more money to get it sorted.
i've in mind a couple of idea, add a couple of more cob, then mono and and uv cfl or in alternative another string of 5 cob
C
cannaisok
me too arf, to power my 5x 10w leds, i have a controller after my 300w ballast to play with the voltage to go from 8,5volts up to 10volts whenever needed untill it starts cooking my chinese leds 
ballast, 2x 12v fans, leds at 9.x volts consume slightly over 65watts.
(20-30€ to build my fixture)
i used 70w cdm/cmhs earlier and consumed 87watts total and had to watch the temperature all the time..
ballast, 2x 12v fans, leds at 9.x volts consume slightly over 65watts.(20-30€ to build my fixture)
i used 70w cdm/cmhs earlier and consumed 87watts total and had to watch the temperature all the time..
I looked at Raspberry and Arduino. It wouldn't be terribly expensive to rig up a system to control current to each COB.
You could do a sunrise/sunset thing, or run the "sun" across the sky, turn infrareds on at sunset, etc. You could run a channel to the huey/dehuey and coordinate rainy overcast days ...
Fun to think about, but not economically practical.
Thanks for the help, Dion!
One thing I forgot to mention about cheap Chinese drivers, most of the really cheap ones are designed for outdoor floodlights, so the PCB is potted in black silicone crap that's damn hard to remove.
That means if you do something that causes the onboard fuse to blow, you are not going to be able to get it open to replace it!
Some of the Chinese drivers come in proper cases you can unscrew to get at the PCB, and some are just bare PCBs that you put in your own case. I am gradually changing over to that type.
This one has got me interested.
http://www.ebay.com/itm/36V-3A-Proj...-Driver-Light-Lamp-Power-Supply-/262404505487
It's rated at 100W 36v up to 3A but it's got a trim pot for adjusting the current.
So a 100W dimable for $12 might be possible. I haven't ordered one yet, very tempting.
That means if you do something that causes the onboard fuse to blow, you are not going to be able to get it open to replace it!
Some of the Chinese drivers come in proper cases you can unscrew to get at the PCB, and some are just bare PCBs that you put in your own case. I am gradually changing over to that type.
This one has got me interested.
http://www.ebay.com/itm/36V-3A-Proj...-Driver-Light-Lamp-Power-Supply-/262404505487
It's rated at 100W 36v up to 3A but it's got a trim pot for adjusting the current.
So a 100W dimable for $12 might be possible. I haven't ordered one yet, very tempting.
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You've obviously had better luck than I have with them and I wish you all the best in your future grows. I did not run them that gently and I'm sure that was part of the reason they didn't last.
I have eight 100W COBs in a roughly 4x5 space and that is already way more hardware, wire and shit to deal with above my plants than I want so I can't imagine what it would be like to have 40 or more of those chips and the associated wiring hanging in that space.
If they work for you that's great, I just think the larger the grow space the more it's worth getting gear that you can reliably push harder and reduce the clutter and infrastructure above your plants.
A 4' x 5' space is massive, as I mentioned before in post #1028, the Chinese COBS are essentially the next step up from using CFL.
Would you try lighting a 4' x 5' with CFL? You could certainly do it, but you would need a lot of them, and you would be dealing with a lot of heat. Same goes for the Chinese COBs, in that space I would expect to use about 80 of them. They work best around one per a 6" x 6" square.
