Let's talk DIY lights

I have artic, and have used both pads and grease without any troubles. In fact, if anything I think pads work better. Did they say why?

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Pads are neater because you don’t have to deal with messy grease getting loose. Brigelux says they are okay for their lower power COBs but they just don’t transfer heat quite as well. But now that I think about it, running Vero29s at 1/4 power to get high efficiency, it probably doesn’t matter. If you were running more toward full power, I would follow their advice.

At my power level, I probably don’t need the copper heat spreaders either. They don’t say anything about them. But holy crap, they can really conduct heat well. I was drilling mounting holes in them and I could barely hold them they would get very uniformly hot in seconds. Aluminum or steel never did that.

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Sorry not to reply earlier. out with family. The driverless COBs probably can’t be run below 95vAC forward voltage. I haven’t used a dimming switch to find out, but they have a built in dimmer circuit that you can solder tiny wires to, so I would guess the forward voltage is pretty close to 110v. @1BigFella is absolutely right about the Chinese COBs being much weaker light. I’ve seen 30watt non-Chinese COBs that are much brighter than my 50watt. These driverless COBs are mostly made for Chinese built COB spotlights. I guess the cob maker decided to build grow COBs. I’m just stuck with what I got until I can scrape together enough money for good COBs and drivers to build a 800 - 900 watt light for flowering. I just have to keep them close to the plants. They haven’t shown signs of light damage. @Daddy

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@dbrn32 I turned on my new grow lights on the lowest setting for additional lighting to clean the house for awhile while mrs covertgrower took a nap. I got the temp gun out and it’s a magical 78°F on the heatsink side, and a magical 82°F on the COB’s themselves after running for an hour. I’m thoroughly amazed at this point. Just wanted to share. As I utilize them more, I’ll give you a temp report again when in proper use. Just wow though, you get what you pay for.

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Yes I agree. If you were pushing them hard, you would want grease and a very good one at that. Some of the pads are as good or better than some of the cheaper greases as far as thermal conductivity goes. The other thing, is that grease is only good as you apply. And too much will press through the holder and onto the les. Not the end of the world, but not great either.

I think even at 100 Watts you’d probably be good with pad. That stuff is all at maximum output. Below 100, plenty good.

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That shows you have good transfer. I will say that the ir guns aren’t the most accurate for us to use. The light source can mess with them, as well reflection even off of the anodized aluminum.

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@dbrn32 you’re correct, but to get a general idea, this works. All out of likes for awhile.

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You’re all good my friend. And if it makes you feel any better, they’re pretty much all made in China lol. Some just engineered a little better, and probably put together with more quality assurance.

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@1BigFella I know the reason they recommend the grease now after doing my build, because of the mount location on the vero 29 and the thickness of pads…the cobs deform alot and no longer sit flat and flush. so they lose contact area for heat transfer. I am not going to worry about it at this point though because i run the series D but at some point I will probably redo them with grease.

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I’ve noticed them flex with the grease too. But I think it’s just the holder flexing. You can really tell with the squish of the grease. But I think it’s just a matter of the holder not being flush. I don’t believe the cob itself flexes.

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By “holder” do you mean the plastic outer ring with four mounting holes? Mine have not deformed at all. They are still perfectly flush with the heat spreader they are mounted on. Could you be running yours too hot, so the plastic melted? That COB-to-heatsink thermal connection is critical! It’s just a few degrees below the LEDs junction temperature and if the heat does not transfer out of the COB it burns up.

The other thing that is important for good heat transfer is that the heatsink surface has to be perfectly flat and polished so it’s like a mirror. Then you need to use just a little bit of thermal grease spread evenly over the COB heat transfer pad. If grease is “squishing” after the mounting screws are torqued, you probably used too much grease.

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Didn’t deform with heat. They flexed during install. The pads are pretty thick and the Vero 29 have their mounting holes on the outside of the housing instead of near the center like the cree.

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Yep I agree with @Daddy. You could physically see them flex as you were tightening. Long before they were ever powered up. The first set I did was with liquid, they have been in service almost 2 years, zero issues. Did another set with pads like 5 months later, still in service with zero issues as well.

The first set was my 2nd cob build, and aren’t even gen7. I didn’t know about the pads at the time. But when I tightened excess grease pressed through the holder and onto the les. This has proved not to be an issue to this point, but I just didn’t like it. Which is what led to me using the pads. Since I’ve done probably 20 more vero’s between the 29 and 18, and a whole bunch of Cree and citizen, all with pads. No reports of thermal transfer issues. But as u stated, I don’t run them particularly hard either. I would imagine it could make a difference if you were anywhere near max output.

I think the flex is just from spring tension on the holder anyway. But every one I’ve done has had it.

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I’m pretty sure they are dimmable. The 110v version I have has a circuit on it that looks like it is made for adding a dimming pot. You’ll notice that 2 pins have solder on them already.


I think this is the dimmer circuit at the bottom of the board. The 220v version doesn’t have this.

I don’t know why it’s such a big secret, but I can’t find a schematic for these lights. A guy on YouTube called Big Clive has a few videos about the design of these things. He scraped all of the coating off and drew a schematic of the 50 watt spotlight version. It looks about the same as the ones I have except for the LED colors. @dbrn32 @1BigFella

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If I had to guess, that has something to do with voltage configuration more than dimming capability. But I don’t know for sure, so maybe.

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Are you looking at the bottom of the cob or the side? I wasn’t very clear about that on the earlier post. The terminals on the side are the 110v inputs. I’m mounting 4 single 50watt driverless COBs each on their own heatsink to run some temperature tests. I guess I’ll try soldering wires to the circuit with a 10k pot and see what it does. All it can do is blow it up at worst and nothing at best.

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Don’t dim it to zero though. I’m sure it isn’t rated for that lol

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At least they only cost $3 so I won’t cry too much if I blow one up

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I was looking at part circled in blue.

I’m not entirely sure what it’s for. Did the guy you noticed on YouTube claim they were for dimming? They could be, but there seems like an awful lot of pins for that to be the intent. I figured they would be more for tuning the circuit prior to leaving factory. Outside of knowing what’s there though, I can’t be sure.

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The ones he was looking at don’t have this feature. I you look at the second picture I posted to @Daddy, you don’t see this feature either. The second picture is a 220v version that they accidentally shipped me a dozen of. It doesn’t have this either. The 110v lights are a fairly new product from the little I can find on the internet about them. I don’t think it’s a tuning circuit. In a few days, we are going to find out what it is. If I had some 4-40 x 1/4" screws to mount the COBs on the Heatsinks I tapped yesterday, I would try it out today. I just need to figure out what pot to use.

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