Built myself a COB light

[blep48]

Hi, I'm new here. After reading a few threads, I got the bug to build myself a COB light. I'm a LONG time electronic tinkerer, so the electrical stuff is no big deal. I just needed to learn how to size CC LED drivers and figure out a frame and cooling. I'm not growing cannabis at present. I just got interested in tinkering with hydroponics and ended up here. I'm growing lettuce, basil, beans and strawberries for now.

Since aluminum is expensive around here (retailers seem to think it's GOLD!), I built my frame out of wood. I'm in construction, so it cost me nothing. Just ripped up some clean spruce 1x4 into 3/4" x 1/2" strips, and bolted it together with 3/16" stove bolts. Cheap (free!), plenty strong enough, light and super easy to work with. The heat sinks are never going to get hot enough to ignite, or even char, wood - the COBs would have burned out long before things got anywhere near that hot.

For now it's a linear light - four Bridgelux Vero 29 3000K 90CRI COBs spaced 12" apart. Later I'll build another X frame for a square 2x2 light, and move the lights to that (or maybe buy more).

I know my wiring isn't beautiful, but it's solid enough as long as I'm not rough with it. All joints inside those Marrettes (wire nuts) are soldered (Marrettes aren't safe for stranded wire) - I didn't have big enough heat shrink tube. The driver is remote, on about a 15' cord - I want that heat outside any grow room I might use the light in, and I don't want the heavy driver on the light.

It draws 2.21 amps at the wall at 115V = 254 Watts. Might not be totally accurate - my clamp meter is real old and I don't totally trust it. Got some wacky readings before it settled at 2.2ish. But that seems correct - the driver is rated at 250W.

Digikey's (and Mouser's) prices are fiercely high, but their inventory is great and service is so amazingly fast that I gladly pay them without bitching.

4 - BXRC-30G10K0-D-73 Vero 29 3000K (Digikey 976-1409-ND)
4 - NX300159 Aavid Thermalloy 70W Spot heat sink (Digikey 1061-1154-ND)
1 - Mean Well HLG-240H-C1750B LED driver (Mouser 709-HLG240H-C1750B)

4 - 0688014229 PICO-EZMATE 18" Harness for Vero (Digikey WM9599-ND)

Don't bother with the Pico-EZMate connectors. They're a waste of money. The EZMate connectors are tiny fiddly little things that are a bit difficult to snap in properly. They're really weak - takes very little abuse before they pull off or the wires pull out. In my opinion (I didn't measure the wire or calculate this) the wire gauge to the connectors is too small for the amount of current they're carrying. Maybe I'm wrong... Whatever - they're crap!

The Vero 29's integral clamp has thermally isolated solder pads that work great. You can easily solder to them even when the COB is installed on the heat sink. If you can't solder... learn to solder.

I tried to run the light with passive cooling at first. It's almost enough, but at ambient temp around 75F the sinks were hotter than I would like. Not so hot that I was worried about hurting the COBs or losing much light (these COBs get dimmer as they get hotter), and I could hold my fingers on the sinks right at the back of the COBs without pain. But it's not super summer hot here yet. Another 30 degrees of summer heat and it would be a different story for sure. Screw it. I ordered the expensive Synjet ZFlow 90 "fans" (coolers) that fit these heat sinks.

4 - NX200102 Aavid Thermalloy Synjet ZFlow 90 Level Select 12V (Digikey 1061-1053-ND)
4 - WALLS-C4600-001 Aavid Thermalloy Synjet Wire Harness 600mm (Digikey 1061-1050-ND)

The Synjets aren't blade fans. They're a diaphram air mover that vibrates at (I assume) 60Hz and just sort of rapidly puffs air back and forth across the heat sink. I tried one before installing and was very unimpressed - it seemed very weak. But after installing them and testing in the afternoon heat I'm sold. They work great! The heat sinks are running nice and cool. Synjets are rated to last something like 200,000 hours in outdoor conditions. They just make a quiet hum when they're running. On the ones I bought there are three speeds available - Silent, Standard and High Performance. I'm running them on high. They have PWM versions as well that you could control with a microcontroller or a 555 timer or what have you.

I power all four coolers with a tiny little 12V 1.5A LED driver. That light switch does nothing - I needed a cover for the junction box and that's what I had on hand.

I have a 400W HPS light and tried to compare it side by side with the COB light. I can't tell which is brighter. They're both blindingly bright! The HPS "seems" brighter because it's all from one emitter, rather than being divided by four emitters. Also it's hard to compare because the HPS is so orange, and the COBs are more white. Guess the only proper way to compare is with fancy expensive light meters. I have none. Anyway, the plants seem super happy with the COBs. (Color isn't quite right in the photos. All the red in the 3000K COBs throws off the auto white balance in my camera. Too lazy to set a custom white balance.)

 

[TorturedSoul]

Hello, blep48, and welcome to 420Magazine.com.

Nice first post! I'm a big fan of all things "DiY." I'd click on the little icon to award you some REPutation points, but I've had so many people add to mine over the years that a single award from me would completely max out your "little green boxes" :rolleyes3 . So it is my hope that someone normal err... with a reasonable reputation power comes along and does so. I'd just feel funny about turning your single green box into the maximum amount when you have only a single post. But know that the thought is there.

Since aluminum is expensive around here (retailers seem to think it's GOLD!), I built my frame out of wood. I'm in construction, so it cost me nothing. Just ripped up some clean spruce 1x4 into 3/4" x 1/2" strips, and bolted it together with 3/16" stove bolts. Cheap (free!), plenty strong enough, light and super easy to work with. The heat sinks

Just out of curiosity, how much did all of your heat sinks cost? As far as I know, the whole point of using aluminum for a frame is so that IT can serve as one large heat sink (possibly even a passive one, where fans are not required). Would an aluminum frame have been cheaper than the heat sinks, or the heat sinks plus fans, if a single large aluminum heat sink (IOW, an aluminum frame) would have served the same purpose?

Since you have the heat sink department covered, no, there is no reason why a wooden frame cannot work (and free is always good!). If it was me doing it, I would definitely paint that wooden frame with a good primer and a couple of coats of outdoor paint so as to provide protection from humidity and/or water. Things can happen in a grow room, lol. And wood, especially if it becomes damp, is probably a good environment for mold (et cetera).

All joints inside those Marrettes (wire nuts) are soldered

Good man.

The driver is remote, on about a 15' cord - I want that heat outside any grow room I might use the light in

Makes perfect sense to me, and if I was building such a setup, I would do the same thing. That's why we place our HID ballasts outside of the grow room, after all.

Might not be totally accurate - my clamp meter is real old and I don't totally trust it. Got some wacky readings before it settled at 2.2ish.

Those "Kill A Watt" devices that one plugs into an electrical outlet and then plugs the thing that he/she wishes to check into are pretty inexpensive. And are reasonably accurate and reasonably durable (as long as you don't try to charge your electric vehicle through one :rolleyes3 , in which case you'll probably end up figuring out how to rebuild one - or how to put out a fire, I guess).

Vero 29's

Aren't perfect, but they seem to be pretty decent and a good value. From what I have read (no personal experience with them).

The Synjets aren't blade fans. They're a diaphram air mover that vibrates at (I assume) 60Hz and just sort of rapidly puffs air back and forth across the heat sink.

Very interesting. I had never heard of such a thing before.

I have a 400W HPS light and tried to compare it side by side with the COB light. I can't tell which is brighter. They're both blindingly bright! The HPS "seems" brighter because it's all from one emitter, rather than being divided by four emitters. Also it's hard to compare because the HPS is so orange, and the COBs are more white. Anyway, the plants seem super happy with the COBs. (Color isn't quite right. All the red in the 3000K COBs throws off the auto white balance in my camera. Too lazy to set a custom white balance.)

I can remember back when I thought a 400-watt HPS was "blindingly bright." Way brighter than the fluorescent tubes I'd tried prior, the mercury vapor "experiment" (no, of course it didn't work for growing plants, lol), and even the 400-watt metal halide that I'd been using right before getting my first 400-watt HPS. Actually, my first 400-watt class HPS was a 430-watt (bulb and ballast) one with extra blue (the additional 30 watts, I suppose). Fired that puppy up for the first time... The "blue" came on. Wow, that's pretty bright. Okay, not as bright as I'd expected, but... Ohwaitaminute, it just got 100x brighter. And now it's getting even bri-- OW OW OWOWOWOWOW my eyes, lol.

Just rambling. I wish I still had those 430-watt setups. And the eyes (vision) that I had at the time, too.

BtW, there's nothing wrong with running your COBs AND your HPS. That would give you both more light and, presumably, a fuller spectrum. Maybe not a perfect spectrum, but a fuller one.

 

[blep48]

Hello, blep48, and welcome to 420Magazine.com.

Nice first post! I'm a big fan of all things "DiY." ... But know that the thought is there.

Thanks TS.

Just out of curiosity, how much did all of your heat sinks cost?

Canadian pricing: Sinks - $31 each. Synjets - $32 each (another $2 each for wire harness (necessary, and good quality)). COBs - around $35 each.

If it was me doing it, I would definitely paint that wooden frame with a good primer and a couple of coats of outdoor paint so as to provide protection from humidity and/or water. Things can happen in a grow room, lol. And wood, especially if it becomes damp, is probably a good environment for mold (et cetera).

Good idea.

Those "Kill A Watt" devices that one plugs into an electrical outlet and then plugs the thing that he/she wishes to check into are pretty inexpensive.

I just ordered a new clamp meter. I can check the old dog's accuracy with the new one. I use them for work anyway, so I don't mind the cost.

Very interesting. I had never heard of such a thing before.

I had never seen an air mover like that either. Was pretty confused for a while when I first read the datasheet. But they work like a damn!

Fired that puppy up for the first time... The "blue" came on. Wow, that's pretty bright. Okay, not as bright as I'd expected, but... Ohwaitaminute, it just got 100x brighter. And now it's getting even bri-- OW OW OWOWOWOWOW my eyes, lol.

Ya, I remember my first time with my HPS. I was amazed by it at the time.

BtW, there's nothing wrong with running your COBs AND your HPS. That would give you both more light and, presumably, a fuller spectrum. Maybe not a perfect spectrum, but a fuller one.

Very true. I hadn't considered that, but I certainly could do that. Or veg with COB and flower with HPS.

 

[TorturedSoul]

I just ordered a new clamp meter. I can check the old dog's accuracy with the new one. I use them for work anyway, so I don't mind the cost.

Which brand/model? If it's a Fluke or something similar in quality (and price), I'll probably never be able to afford it, lol, but I still like to collect recommendations of high-quality tools/etc. because, for whatever reason, a lot of people ask for my opinions on things.

I hadn't considered that, but I certainly could do that. Or veg with COB and flower with HPS.

I once saw a grow where the gardener was attempting to figure out which performed better (LED or HPS). But, instead of partitioning his grow room into two spaces with a lightproof barrier betwixt the two, he just placed one type of light on each side :rolleyes3 . By the middle of flowering, the plants that were on the HPS side - but reasonably close to the middle - were all growing towards the LED side. So he thought, "Well, the LED must obviously be the greater performer." So, when harvest time rolled around, he was surprised when the harvest from the side of the room with the HPS... turned out to be noticeably heavier. Go figure...

Anyway, I seem to be misspelling every other word (including, it turns out "mispelling") because my fingers are getting ahead of themselves - which is unlike me, since I've been typing for... 36 years? Must be well past my bed time. So have a good evening and all that, I'm off to go get horizontal.

 

[blep48]

Which brand/model? If it's a Fluke or something similar in quality (and price), I'll probably never be able to afford it, lol, but I still like to collect recommendations of high-quality tools/etc. because, for whatever reason, a lot of people ask for my opinions on things.

I bought a cheapy (UNI-T UT210E), since I use clamp meters much less often than regular multimeters. I mainly bought it because it gets pretty decent reviews considering the price, and it does DC amps on the clamp, which is unusual on a cheap meter.

My good multimeter is a Fluke 177. Number two is a Milwaukee 2217-20. It's no Fluke, but not bad for the money. Numbers three thru n are a bunch of el cheapo beaters.

I once saw a grow where the gardener was attempting to figure out which performed better (LED or HPS). But, instead of partitioning his grow room into two spaces with a lightproof barrier betwixt the two, he just placed one type of light on each side :rolleyes3 . By the middle of flowering, the plants that were on the HPS side - but reasonably close to the middle - were all growing towards the LED side. So he thought, "Well, the LED must obviously be the greater performer." So, when harvest time rolled around, he was surprised when the harvest from the side of the room with the HPS... turned out to be noticeably heavier. Go figure...

Hmm... Very interesting... Might be a fun experiment to attempt to replicate.

 

[blep48]

Just a note for anyone who doesn't think Bridgelux Vero 29 3000K 90CRI lights have enough blue for veg: Put your minds at ease. These lights veg like crazy. I've never seen happier, faster growing plants. And these 3000K lights have lots of red as well for flowering. I'm not growing cannabis at present, but here's a couple pics of my romaine lettuce and a pea plant. Four heads of lettuce have been harvested out of there, but you can't tell - the other heads immediately fill any empty space. They're growing in a DWC tub (GH FloraNova Bloom).

 

[TorturedSoul]

Lettuce and peas don't exactly have HIGH lighting requirements, do they? (Unless you have... tropical varieties, I suppose?)

Still, your plants do look pretty healthy.

 

[blep48]

Lettuce and peas don't exactly have HIGH lighting requirements, do they? (Unless you have... tropical varieties, I suppose?)

Hmm... Maybe you're right. I also have a bunch of strawberries, basil, and beans under the light. All are growing like mad, but that's not a very scientific finding, is it? More anecdotal, and proves nothing. But I'm convinced, and I'm blaming it on the light - I like my little light.

I'm not convinced that cannabis is so incredibly special in its light requirements. It's just a plant. Long ago (back in the overgrow.com days) I vegged fairly decent weed under fluoros (flowered with HPS) - it wasn't incredible, merely good. But that could have been genetics. The seeds were unknowns that someone gave me. Yield was pretty good. Of course it could have been better (and grown faster) if vegged under something more intense, with better spectrum.

 

[TorturedSoul]

Oh, I agree that one can grow cannabis under less light than "a sun in one's closet" (but it helps ). However, cannabis can process a great deal of light-energy in a day - even under ambient CO₂ levels - if the temperature is warm enough (but not too warm). Add a fair bit of supplemental CO₂ and bump the temperature up a little, and it can process even more light-energy.

None of that changes the fact... that I'm impressed with your DiY.

I vegged fairly decent weed under fluoros (flowered with HPS)

Once upon a time, I used to use fluorescent tubes for vegetative AND flowering phases (double-decker setup with 400 watts on each level - I think that's the kind of setup that originally produced the concept of "scrog," because such lights can't penetrate their way out of a wet paper sack (so to speak)).

However... <SHUDDERS> I never want to do that again, lol. When I learned about metal halides (and, later, when high-pressure sodium lamps became more common), well... It was almost like learning about sex for the first time.










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