What's new
TerraForums Venus Flytrap, Nepenthes, Drosera and more talk

Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

DIY COB LED info

  • #61
Looks good, Numbulan! If you can use recycled parts, you can get them done cheaper, and that's the way to go!

You are probably right, if you use narrower beam angle, and hang it high, you might get a more even coverage. I've tried relatively wide DIY reflectors (from yogurt container and empty can from canned food), but I'm not using it any more. But without the reflective enclosure, you could waste some light without reflectors. In a grow tent with multiple COBs, the unevenness does get reduced quite a bit. But it is an disadvantage of this types of LED.

pmatil, what's the plastic mirror sheet?
 
  • #63
...and I've already filled up the indoor grow area with moved plants and various pots of seeds (including some edible plants.) Oops. I would have loved to set up a few more of these but I just don't have the space right now. At least the seedlings can likely move outdoors in a couple months.
 
  • #64
For DIY COB, drilling and tapping heatsink is probably the most intimidating part. The rest is something which can be done by anyone who can strip wires and use a screw driver.

I noticed that Cutter is starting to offer pre-drilled heatsink + COB kit. It is not the cheapest, but for the people who doesn't want to drill, this could be an easy option. The shipping is a bit expensive for people outside of australia (especially if you are interested in only a few units). There is 10% discount for the first 2 items with the coupon code.

passive cooling, CXB3590:
Cutter Electronics, Supplier of lowest cost leds on the internet
About 50W for $80 (+$35 shipping). You'll need to get your driver (about $20, including shipping) separately. I would prefer a bit beefier heatsink, but it probably works well.

The following is similar, but it comes with 4x COB (about 200W) and a driver (i.e. a complete kit). About $430 with shipping:
Cutter Electronics, Supplier of lowest cost leds on the internet


Active cooling version:
CXB3590 ($66 + $19 shipping)
Cutter Electronics, Supplier of lowest cost leds on the internet
CXB3070 ($56)
Cutter Electronics, Supplier of lowest cost leds on the internet

You'll need a driver and an AC/DC adapter 5-12V (e.g. cell phone charger).

For the driver, you can use something like Meanwell LPC-60-1400 (data sheet).
Here is the current price (about $16 + shipping):
LPC-60-1400 - Octopart
 
Last edited:
  • #65
It looks like that first kit comes with a 90 degree reflector. I do like the look of the heatsinks in the second kit though they don't provide any binning or CRI options for the COBs.
 
  • #66
Cutter is the only places where you can get the top bin (the best one in each K) easily, which we can't get easily from the US sellers. I think that it mentioned this in the webpage. I think they use the lower CRI for the better PAR output, but some of them may not be the lowest CRI in the given K. So basically, what they offer is pretty much the best for whatever K you choose.

I think you used Ideal COB holder, so it is easy to retrofit Ledil reflector. I think the heatsinks are Mechatronix.
 
  • #67
Has anyone ever tried using a smartphone light meter app? I tried one and it's showing 15,000 lux under my T5 fixture (seems slightly high, but reasonable) and 105,000 lux under the COB which seems very high. Doing a rough calculation of the covered area, the average lux under that light should be approximately 21,500, though it is far from uniform. Apparently I'm blasting my Helis with the equivalent of direct sun on the summer solstice...
 
  • #68
I created a new post to share my current project, especially its future updates on the automation part, but the current step may interest some of you:

DIY 60W COB LED fixture
 
  • #69
duplicate post deleted
 
Last edited:
  • #70
I came across this CXB3590 kit, which was released in 1-2 month ago:

200 WATT CREE CXB3590 (4) COB KIT + MEANWELL HLG POWER SUPPLY FREE SHIPPING - Timber Grow Lights

Similar to Cutter kit, but for the US, it is a bit cheaper. Good components; 4x top-bin CXB3590 driven softly (50W per COB) and the best MeanWell driver. I'm not familiar with the heatsink they use. It is all pre-assembled, so you don't need to do anything. You only have to figure out how to hang them. Dimmer is included (goes down to 10%). $399 + free shipping for 200W (4x 50W). If you assemble the components by yourself, you can save $100 or so, but for people who doesn't have time to assemble or not sure how to assemble, $100 extra may be worth. They also have 5x50W version for $499. PRODUCTS - DIY GROW LIGHT KITS - Timber Grow Lights

This is pretty much the best in terms of PAR efficacy (about 2.5 micromol/J from my calculation), and most LED grow light can't touch it. The PAR efficacy is measuring how many photons relevant to plants are produced for a given amount of electricity. In comparison, Fluece (=BML) SPYDRx, released in early 2016, is one of the very best and achieves only 2.2 micomol/J. I said "only" 2.2, but it is a very high efficiency number. You should know that cheaper LED grow lights give about 1.0 micromol/J, only slightly better than T8 or T5HO. Very good HPS is around 2.0 micromol/J. In terms of lumen (not so relevant, but people are more familiar with it), it is giving about 177lm/W.

In terms of COB front, I recently learned about a better alternative to Cree. I don't need a newer grow light for me, but if you are interested in DIY route, I would definitely look into Citizen CitiLED COB Series Version 5. There are several sizes, but something around CLU048-1212C4 seems to be the sweet spot in terms of price and efficiency ($12.55 from CDI). This is a smaller COB, so you'll need 2 of CLU048-1212C4 to replace 1x CXB3590. At the moderate driving current, the efficiency is very close to CXB3590. Maybe you can drive it at 1050mA (36.8W), which gives 169lm/W @ case temperature (Tc) of 50C, or better yet at 700mA (23.7W), which gives 179lm/W (similar to CXB3590 @ 50W).
 
Last edited:
  • #71
That's a nice find there, and I'm glad there's finally a US supplier. I wish more premades came with the CXB3070's though, since they are cheaper. I was able to assemble those for about $60 each (with a separate driver for each,) probably more like $75-$80 if I had to buy heatsinks. They even carry reflectors too, though only 120 degrees.

Edit: The more I look at these, the better they look. The kits even have a built-in dimmer and don't require fans!
 
Last edited:
  • #72
Yes, it is a pretty nice kit, and a pretty good deal for people who doesn't want to assemble. The MeanWell HLG drivers have one of the highest DC/AC conversion efficiency, and the 3-in-1 dimmer is handy.

I did look into the Cooliance heatsink. It is supposed to be 100mm x 70mm Cooliance CPL10070 according to post #30 in this thread.
Thermal resistance is 1.03C/W. So the LED will become ambient + about 25C. So it is within the operating limit of LED and it probably works. Passive aspect (no fan needed) is nice, but I would prefer a bit more cooling for better efficiency.
 
  • #73
I'm sure you could just add fans to those heatsinks yourself, as long as devising a mounting system isn't too difficult.
 
  • #74
I just spent a bit of time to write up a blog post to help DIY LED grow light builders. The DIY COB post is one of the most frequently accessed post in my blog for some reason (even though I think other biological posts are more fun to me), so this is a follow up, and explain more fundamental principles of LEDs. In this post, I tried to explain the basics of driver selection and the design process. Here is the link to the blog post. It talks about the multiple LEDs driven by a single driver, basics of driver and LED efficiency, and super simple thermal protection. I tried to target beginners, but it might be too much information or a bit too technical. Hopefully, it is useful for some people since winter is coming (well, it's been here for a while in Alaska).

I also updated the original DIY COB blog post with newer information (i.e. there are much better/cheaper COB than Cree COB).

Here is my recently cleaned grow tent with 8x COB LEDs.
P9170002.jpg


Here is a PPFD map of 4x CXB3590 with HLG-185C-1400B. It is showing amazingly even distribution of light over 120x120cm (4'x4') area in the grow tent. The unit is micromol/m^2/s.
evenness.top.png


Here is the relationship of dimming vs overall efficiency. So with this driver, using dimming function doesn't decrease the efficiency unless you dim it extremely (i.e., as long as you stay above 30% of the full power, it is explained more in the blog post).
dimming.png
 
Last edited:
  • #75
Looks great! I'll have to read through the new blog post sometime. I'm still using a single COB each for 2 grow areas myself, and recently added reflectors to aid in more even light distribution. I feel like panel or strip lighting is a better option for how my grow areas are set up, but I still love these COBs.
 
  • #76
Sounds good, numbulan! Which reflector did you use? With the linear LED modules, Samsung released H-series a couple month ago, and it is quite amazing in terms of efficiency. I'm trying it on top of pygmy drosera. It is a bit pricey, so it might not be economic in most places (other than places with high electricity cost).
 
  • #77
I ended up buying the Ledil C12599_LENINA-W which was one of the few reflectors readily available from US suppliers with a reasonably even light distribution pattern and narrow beam angle (so I could raise the lights up higher.) The light falloff areas on the edges are very useful for Nepenthes and other lower-light plants.

The only problem I'm having with these is that the Ideal reflector adapter you have to use for these leaks quite a lot of light out the sides and I haven't quite figured out what to do about it yet.
 
Last edited:
  • #78
Thanks for the reflector info. Did we partially talk about this on one of FB group? It is difficult to tell who is who (between FB and here). FB group is rather tedious for discussion (ok for show-and-tell), so I tend not to post there, and I might not have replied correctly. So this might be redundant.

I haven't used it but, this kind of V-shaped super clear silicone lens seems to be interesting. It achieves extremely homogeneous output:
SIO3 Silicone Lenses for HB and COB LEDs
PL1824SR for 60degree, PL1825SR for 90 degree and PL1845SR for 120 degree square. It is more expensive than reflector, though. Also it needs fairly large heatsink to mount the lens. I didn't find the information about the optical transparency etc in their web page.
 
  • #79
Yes I believe I did speak with you about it on Facebook. I thought we had and was confused when I didn't find any of it in this thread.

And yes I looked at those lenses. I could not figure out how they're supposed to fit around the mounting brackets for the COBs and the lack of published light transmission efficiency worries me. They also don't have a beam angle narrow enough for my purposes - the reflector I'm using has an officially-rated beam angle of 45 degrees, though the brightest area is closer to half that.
 
  • #80
After you pointed out the lack of specs in Khatod lens, I did look around more info, but I didn't get the optical transmission efficiency. This page mentions silicone can have up to 95% efficiency, but it would be nice to have the spec for this particular product:
http://www.vision-systems.com/conte...n/Resources/SVL_IEC whitepaper_Oct2015_v3.pdf

But your solution is cheaper, and it sounds like it works well for your space. At near the bottom of the Khatod page, there is a ring which is used to attach the lens to the heatsink. So the lens is sealing against the heatsink, and it creates water tight protection. I think CXB3590 + ideal COB holder is too big for this, but it works with anything smaller (including Vero 29, CXB3070 etc). You have to use a different type of COB holder (Bender& Worth) with CXB3590. More info here: Ultra Clear Silicone Lenses – Photon Labs LLC Their bigger heatsinks (SST-X) have the holes pre-drilled/tapped for this lens. The smaller ones are too small for this lens.
 
Back
Top