Let's talk DIY lights


I ordered quite a few a while back, I think with bulk discount I paid around $12 each after shipping. Compared to cost of buying suitable extrusion, I didn’t think it was too bad. And they’re predrilled or ideal cob holder, so pretty easy install.

You have any pics of your sink configuration? I always try to get at least 6 square inches of aluminum per heat watt when going active cooling. If you’re not pushing them too hard, about the size of a pc cooler will work if it has good air movement. @1BigFella


Great price. Looked like 25 each for me. I calculate I should have 216 square inches per heat sink. By your 6 in benchmark I should have 270 square inches, but I’m going to always have air being forced through them by an exhaust fan. The internet shows a graph and heatsink performance goes WAY up with some air flow. I don’t have any photos yet because I have not built one yet. I need to fire up the cutoff saw and make some drill jigs. I plan to make it single-sided so the bottom is smooth for the copper and cob. Just imagine 12 two inch fins held together by all-thread with 1/2 inch tall by 1/4 inch wide spacers at the bottom of each fin.

I’ll try a drawing upload: $HeatSink


sweet @dbrn32 could you recess the cxb’s some? that might tighten things up a bit…


You are correct. You can safely use considerably less heatsink material when actively cooled. Like I posted earlier, it’s about 6" squared of surface area for active cooling. I wanna say that the magic number was around 17" squared for passive cooling. And those numbers are per heat watt, so you shouldn’t have to calculate the entire power of your cobs. Also, I think that active number requires fan blowing directly on sink, keep that in mind while laying everything out.

The prices on the passive pin sinks does seem a little high sometimes. When considering the alternatives, it’s not ridiculous though. I’ve used the 5.886 extrusion from heatsink usa, it comes I’m around $2 per inch shipped. A decent 120mm fan is usually $10-15, power supply, wiring, and connectors add up too. When it’s all said and done, it’s not really any cheaper unless you have stuff to use already. Even then, any difference can be made up over time if you calculate the energy fan consumes into your system efficiency.

The only way to get over is be able to recycle sinks or use salvage parts. If you’re not having to buy any heatsink material, the efficiency loss from power supply for fan and fan itself is negligible. Probably 10-20 watts total per hour. As long as what you have is keeping the cobs cool enough to not hurt led efficiency, you’re talking about a couple dollars of energy cost per grow.


I’m thinking that’s about the only option I’ll have. Right now I’m a little torn on what that will mean. I don’t want to increase the height of the fixture too much, if goes as planned this will end up in tent that’s 4’ tall. Also, the possibility of then having the qb sink blocking some of the light. I could install reflectors, but that will increase size even more.

My alternative as of now is to mount the pins on top of the outer edge of qb sink, and to configure my frame with .125 angle to keep them plumb. Not a total solution, but will save me an inch. The only downside there is having to drill and tap some additional mounting holes in all the sinks.

Thanks for the suggestion, I’m gonna let it simmer for a bit and see if I can come up with anything else, otherwise it’s probably exactly what I’ll do


when i was really checking things out it looked like some of the bell looking, ‘‘angelina’’ i thinkk,reflectors?
they looked like that would give you about an inch of recess … build outer frame for needle sinks,then add drops for the qb…from cross members


Yep those are the ones. The only issue with reflectors is that they hit the light output a little to get you that more intense beam. I don’t really need it, but it’s definitely a possibility.


I think the amount of light coming out of the COBs at those steep angles almost makes reflectors not worth while. You have to look at the amount of light that would hit a reflector and be directed down versus that same light just bouncing off your reflective walls. Light coming off the walls could be more useful for hitting the plant on leaves that would be shaded by higher leaves.


That’s the downfall of the reflectors. You do get more intense lighting directly below the cob, but the overall amount of light available goes down. I’m not sure if I would go as far to say that the walls are more efficient at reflecting light than the reflector though. I suppose it would depend a lot on cob spacing and distance from the reflective walls.


Now for HID or fluorescent bulbs, reflectors more than double the light going to the plants, so they are worth it. LEDs not so much. The payback period is probably longer than the rest of your life!


Absolutely. That’s because on both of those 67% of the light produced is heading in a direction opposite of your plants. Even at the losses from the light being reflected, it’s still way more light than you would have without the reflector.


Well I am a long time lurker of the site, but have finally joined. @dbrn32 If you have time could you give me some input and thoughts about what I want to build? I have a 6x4 open grow area with 6 plants (lets call it a pod), so its 2 ft from center to center on each plant so it is actually 4ft x 2ft with 1 foot overhang on sides and ends. I want to build a custom cob fixture that is 6ft x 4ft with 3 rails of 4 cobs each(length wise). The cobs will be 6 inches setback from side and ends (so each cob would be about 6 inches off center of each plant but 2 cobs for each plant, with me so far lol?

Parts list
VERO29 4’ X 4’ GROW KIT -749.00 from rapid as a starting point
(4) 3000K 90 CRI cobs (down the center to help with flowering)
(8) 4000K 80 CRI cobs (outboard sides) rapid does not list these so I dont know what part number to search for
(3) MEAN WELL HLG-240H-C2100B upgraded drivers or do I need the 320H?
(12) 140mm heatsinks cause I cant find bigger
(3) external pots
No reflectors because I want blended light
I use Titan controls so I would want this all wired off of a single 220 plug
SO about $900 and about $1 per watt

Now if I am correct, which I am sure that I won’t be…This should pull 930 Watts correct? What would the amp draw be? Would this be a good (full grow) combination? I can supplement with a HID as well if needed.

For less money I could buy 4 600w Meizhe and have a little more wattage but I think the PAR on the COB with still be higher? Thanks for taking a look brother.


volts x amps = watts, so 930 watts / 220 volts = 4.2 amps

Be careful when you compare COBs to some Chinese LED. They may call it 600 watt but it might only draw 350 watts from the wall. That extra 250 watts doesn’t just appear out of nowhere. Vero 29 COBs are run in the 70–100 watt range if you want efficiency. I think they can do greater than 200 watts if you have GREAT heat sinking with fans and don’t care about efficiency. And those are REAL watts, not fake HID-equivalent watts.


I do understand that @1BigFella, what I was saying is that I could run 4 600w Meizhe (275 true watts each) for less money ($600) but I think the cobs would still have a better PAR at full coverage area?


Off the top of my head everything looks pretty good. I’m kind of multitasking at the moment, will sit down and crunch the numbers as soon as I get a chance, probably an hour or 2.

I think I have a pretty good picture of your grow, would I be asking a lot if you gave me a quick sketch? Just to be sure I see it the right way. Also, are you completely decided on the Vero 29? There’s nothing at all wrong with the vero, but you may be able to get into a citizen or luminous and save a couple bucks.

It’s pretty clear you’ve done your homework! Like I said, as soon as I get a few minutes I’ll double check the numbers and layout, but at a glance everything looked pretty good.


Ok, so I’m glad I didn’t say it was for sure good on the fly. You didn’t state which version very 29, which will pretty much determine which driver you need. To get in the neighborhood of 900+ watts with 3 drivers, they would definitely need to be hlg-320-xxxx. The first set of numbers determine rated output. The 320 is 320 watts and the hlg-240 is 250 watt driver. So three of the 240’s would get you to about 750 watts loaded to the max. But you kind of have to know what the cob voltage is to determine the best driver fit. If I remember the b version is around 69 volt cob, the c version is 52 volts, and don’t version 36 volts. Forward voltage will vary slightly depending on operating current, but we can cross that bridge later.

There’s definitely more than one way to get wherever you want to go though, and I’ll do my best to help you get there. What were you trying to target for size of your light?


Just a quick sketch of my layout idea.
I wasn’t sure which 4000k part number I would be looking for or if I would have to step up to the 480 driver.
I am liking the vera29, they seem to be a real work horse and a few dollars isnt going to bother me at this point.

So I am thinking B series cobs 90cri for the 3000k and 80 cri for the 4000k when I can find it and 320 watt b series drivers for external pots. Sound good? and will this light combo run the full grow well?


@dbrn32 And I should run the 320-2100ma? over the 1750ma?


I wouldn’t worry about cri at all. That’s how humans compare it to daylight, which is 100. Plants respond differently. Color temperature is how blueish or redish the light is. 5500 is essentially daylight and 3000 is more red (warm white) so they say use the 5000 end for veg and the 3000 end for flower, just like MH lamps for veg and HPS for flower.

Within the Vero 29 series, pick your color temperature and then pick one of three current/voltage types. They all have the same number of LEDs but they are strung together internally three different ways. Digikey has a nice comparison tool. For example, if you want three COBs on one driver, you could pick 68 volt and then you need a driver that can supply 3x68 volts at 1-3 amps. Or you could pick the 38 volt ones and use a driver that could supply 3x38 volts at 1-4 amps.

And yes, I think the COBs are a better deal because they put out more light per dollar of purchase cost, and you can run them at lower power to save on your electric bill.


@1BigFella I looked at the chart for the CRI 90 and it goes farther into the far red, that why I picked it. Just to help out more with the flowering. And thanks for the info.