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DIY 100w Simple Stealth LED light

3dDream

3dDream

Matter that Appreciates Matter
Veteran
I just put together a simple LED using a 100w cob for a stealth box. What makes it simple? Besides the wire and adhesive it is only uses 3 parts. This setup is designed to be quiet and stealthy, not cheap.

Parts:

cxa3050 cree led - $30
100w led driver - $40-? (i paid $70 for mine and it is dimmable)
wires and thermal adhesive - $20
heatsink - get the biggest most square heatsink you can afford/find/fit. Mine is over 8" square and 2" tall and can cool the light without fans.

work:
I put the cob at the center of the heatsink with a little adhesive and soldered it at the two spots. I think it took longer for the iron to heat up.

I wanted to make a light for a small space and was looking at chinese lights in the $100-$200 range. I built mine with good parts for $150 and it does more than any of the lights I was looking at. The key advantage is that I was able to buy an LED with known qualities because cree bins them by the color temp and how bright they are. I was able to pick the best from the bunch by building my own. The difference could be as much as 20% brighter within one color temp. This thought haunted me when I was about to buy a chinese light with unknown specs.

The CXA3050 shoots out at 115 degrees and covers a wide area. I can run it without any fans and I am well within proper temps because my heatsink is huge. If I dim it all the way up I will need a fan, but I am counting on the air filter to move the air.

Things I learned along the way:

Square heatsinks are better for distributing heat than long ones.
When the fins are spaced closely on a heatsink it is designed to be used for a fan, spaced farther is for passive cooling.
Good thermal adhesive is worth it.
LED lights make tons of heat, but that is their advantage, all of the heat can be removed from one spot.
You can buy LED drivers with potentiometers built into them. No need to wire up anything external if you want to be able to dim the light.

I've seen a couple other growers using this light, I just wanted to post my love for it. It was an easy project to get running.

UPDATE:
I later blow up the 3050 and replace it with a 3070. Only 1/2 of the first grow used the 3050. A 3070 costs a little more and it makes 2x the lumens of the original cob.
current parts:
cree cxa3070 3000k
meanwell cen-100-42 (i love this little waterproof tank)
a used heatsink
 
3dDream

3dDream

Matter that Appreciates Matter
Veteran
ok, from the wall to the driver:



I love the connectors. You pop in the wires and you are done. Makes it easy to disconnect the light and to have many break points in the cord.

from the driver to the heatsink and cob:



A little thermal adhesive and the cob:



That is it. No fans. No tin box. In a year or two I can scrape off the cob and put on whatever is the brightest of the bin latest and greatest cob.
 
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sammyz2646

Member
I would like to compliment your intuition and thought put into this light . I think you brought several helpful items to the table here. That CXA should hold up just fine with some extra paste hopefully. Plus you have creative control with the dim-able driver for protective purposes. I like your heat sink as well. I need some better connectors. I'm still a little ghetto with my wire nuts. I need terminals too, instead of cutting extension cords, etc.


I recently had some thoughts on how to EASILY keep these LED's cool with a simple 4" inline fan and a few feet of lightweight 4" pipe. I like the white 4" stuff at Home Depot. This is intended with the thought that approx 100 watts would be the wattage of each independent LED in this "convection array". The array could include numerous COB's of each growers desired spectrum based on their own research. I recently mounted a 100 watt COB directly in front of a small fan and I'm saying, the airflow kept it very cool. Now I'm not going to go out and buy a bunch of little computer fans and wire them all up!!! there must be a better way. . . . .


Ever go outside in 30 F degree weather, with a 30 mile an hour wind ? Or go stand in front of your A/C unit for like 10 minutes. BRRRR
It doesn't take long to start freezing your butt off due to heat loss via CONVECTION. I too was thinking that for this to work best, the heat sinks would need to be square or rectangular, as I intend to mount them, (or a small array of them), to the pipe, being pushed by that 4" fan. This pipe could circle the room, at you desired height, with fittings for the corners, being pulled by the inline fan. My heat sinks will be inserted from the inside, as the back of the sink is wider than the top and it will fit SNUG inside up against the wall (of the pipe) screwed tightly. I was thinking to still use thermal pad or paste as directed. Mount it to your square-ish heat sink of choice, and then simply cut appropriate sized holes in the pipe. The key here would be to mount the heat sink JUST far enough into the airflow interior of the pipe. Maybe 1/4 in or less, because you really don't want to "restrict" the normal airflow that your fan provides. The goal here is to have the rear of the heat sink in the draft of the airflow inside the pipe, therefore exhausting any heat away with haste. This air would not need be cold at all as it will constantly refresh the hot area behind the chip and heat sink with a stiff breeze of air. I will be building this as I am convinced it will work. I already have these pipes pulling up Co2 in the room from the floor scrubbing full time with the carbon filters. I can just re - route these lines to my desired LED mounting locations and heights. May take some thought

The failure rates of the cheaper, yet effective Chinese cobs ( of any spectrum) would improve drastically over a simple, passive, or potentially undersized heat sink for the desired operation
 
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3dDream

3dDream

Matter that Appreciates Matter
Veteran
luvdemshrooms - I hear you. I actually had the clips for the cob, but did not have the patience to drill holes. When I put on the adhesive the first time I saw gaps under the cob's corners. I put more on to be sure it was covered corner to corner. Maybe too sure! I don't think there is an excessive amount between the cob and the heatsink. I pushed down pretty hard. It is just a little messy around the cob. In the future I will use the clips + thermal paste so I can have the option to remove the cob w/o issue. Thanks!

sammyz2646 - I can't wait to see your light! I am using my air filtration to help cool the led. Your idea really integrates it.
 
S

seedlingstarter

Member
3dDream i think im going to use this same light thanks to you.. I originally was building a panel with 3 watt diodes and 5 watt diodes i only have warm white and cool white and reds right now, still need blue i guess. So instead of buying blue i will be buying either 1 or 2 of these plus its much less hassle on all the soldering. Ill take the white diodes i got and make a led coral reef light. will this do good in something a bit bigger than a pc case?
 
3dDream

3dDream

Matter that Appreciates Matter
Veteran
seedlingstarter - Good luck! It is waaay less hassle. A cob can have 100 leds in it. I don't see how a bunch of 3w can compare. I am growing just fine with a 2700k cob. I am growing small though.

Are you gonna do the cxa3070? that is newer and brighter. Which driver? I hope you find a nice heatsink. These suckers get hot if you run them at max.
 
S

sammyz2646

Member
3dDream; sammyz2646 - I can't wait to see your light! I am using my air filtration to help cool the led. Your idea really integrates it.[/QUOTE said:
That's great to hear that its helping with the cooling. I have my CXA 3050 and the CEN-100-42, the molex holder, just waiting for my heatsink.


I still have my 4 "other" Chinese test lights mounted directly in front of either a fan or the A/C unit blower, (for now). The 630 nm red and several full spectrum 32x3's that I robbed from my light plant and used a better heat sink, so they are not failing anymore. I am excited to get through the necessary testing so that I may nail down the exact setup (with the CXA's) that I intend to got with and incorporate them with that convection/pipe idea. Of course as with any new idea, it is certainly subject to change as information and technology keep trickling in.
Not to mention all the helpful people here who are very kind to share their knowledge and experiences. Good or bad. Even a failed attempt is a good thing, as the lessons learned are the valuable tools
Click to expand...
 
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sammyz2646

Member
So , lots of misc DIY LED parts are starting to trickle in finally, for me here. I noticed after hooking up the molex holder and firing up the CXA 3050, that the holder itself gets in the way of the outgoing light from the cob. Bummer. I will have to resort to soldering unless someone has another suggestion.

I will say that seeing this thing fired up in person is super impressive

I have it dialed down with the CEN -100-42 as my experimental heat sink that I ordered is way too small to run hard or for very long. The kill-a-watt says its ~ 43 watts in this photo----

 
3dDream

3dDream

Matter that Appreciates Matter
Veteran
You are using thermal paste? Just checking.

I like the heatsink. It looks like it is only rated for 50W? Just as long as we stay under 85C and anything below that will give more lumens. I get 700 more lumens running it at 40C. If you run the driver all they way up I think it will be running a little hot. What is nice is that you can find the sweet spot for your setup by dimming the driver (dimming FTW).

You measure the temp at the dot on the cob. I have only measured the heatsink so far. Looking to borrow a laser reader.

Really cool stuff! Thanks for posting the link for the heatsink. When I was looking I almost went with heatsinksusa, but found something used. I also have limited vertical space.

I am can't figure out how to calculate the watts of heat generated by the led. I did find a cool site to figure out the lumens. Here is the link for the calculator:

http://pct.cree.com/dt/index.html
 
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sammyz2646

Member
Quote- You are using thermal paste?

I did not use it to test on my smaller heat sink, as I only left it on for a few seconds, for testing only. I ordered 2 items to assure I can monitor the temperature on the COB itself.

This temp gun-

http://www.amazon.com/dp/B008EW837S/ref=pe_385040_30332190_TE_M3T1_ST1_dp_1


And these welding glasses, as I have BLASTED my eyeballs a time or two too many at this point with these LED's. It can't be good.


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=181405419030



Of course , these glasses are not to be worn for ANY other purpose whatsoever
 
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sammyz2646

Member
This is my little temporary test light----



Now, doing this, I have learned many things

1- My wires that I chose to solder, are way too fat, and the hot solder just "rolled" off the edges at the top curvature of the wire, so we "flattened" it out and FINALLY after 2 guys and about 30 minutes, Finally got it to stick. NEVER AGAIN will I do this.

The reason I chose not to use the Molex chip holder is because it gets in the way of the outgoing light footprint.


Honestly, I am thinking that a PASSIVE heat sink that is of a SUFFICIENT size is the way I will go.

I think that all the extra power and wiring, along with additional power supplies, that the little benefit you get from those silly little fans, that if we want to talk efficiency ,--------------------------------------Then the most efficient set up seems to be DRIVER/CHIP/ and a sufficiently large enough PASSIVE heat sink that simplifies our overall engineering here.
 
Dr.Nonagon

Dr.Nonagon

Member
S

sammyz2646

Member
Dr.Nonagon said:
You soldered that? Well that proves you are far more brave then I.

I don't know what holder you have but you might be able to grind back the plastic a bit.

If you have the space a passive sink works well. Wiring your fans to an array can be a simple affair though. I use an ac/dc power supply with a 4 pin molex connected to a fan adapter with 6 slots. QUOTE=Dr.Nonagon;6343439]





LOL, yeah, made me super nervous and there was some spitting hot metal flying too close to my little COB. I felt like an idiot. But I read in a tutorial for techs, that 99 percent alcohol and a Q tip does the clean - up nicely. Even right on the COB

This is my Molex holder--

http://www.newark.com/ideal/50-2234c/led-holder-cxa30-array-series/dp/90W0065?CMP=TREML008-005

Like I said, this holder BLOCKS the outgoing light to some extent :(
So I may bring it down as Dr. Nonagon suggested or do without it

Thank you, Doc, for the point toward the little plugs, that helps

I was adding up all the extra watts as well and I went up to 134 watts running this one chip, (the Cree), and the 24 watt power supply and the fan. Seems like way too much power for this contraption. Even being able to run numerous fans w/ this 24 watt power. Lots of trouble and $$$ and extra wiring for a small breath of wind behind the heat sink?

I picked up these warm white 3000k 100 watt cobs for about $7 a piece, and I like the Giorgio heat sinks, they came pre- drilled to fit the Chinese 3000k cob for about $29. So much easier and I honestly think that this chip will not fail, like all the full spectrums and their issues. All being the same voltage and keeping them running at a reasonable level and running cool, this should do the trick-----

This setup will only be drawing ~ 45-50 watts of 3000k warm white ---And will only cost me a total of only around ~$50-----with the driver (~$13)

Click to expand...
 
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PetFlora

PetFlora

Well-known member
ICMag Donor
Veteran
Good to see DIY COBs on IC.

I suggested to mods that they put up a separate DIY LED Forum
 
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