Lil Roach attempts a COB build.....

I'm hesitant about starting my own COB build thread on here as there's many builders I consider experts here in RIU. There's amazing lights that someday I hope I can equal to the degree of quality and detail of Supra, Cpt. Morgan and others.

While these builds are the tops in quality and efficiency.....they are pricey......too pricey for my budget for what is a hobby build for me. My goal is to build an 8 COB (400 watt) light for around $500. Doing so has made me step away from massive heat sinks, $45 COB's and fancy gear that's used in other builds. So I had to put on my Macgyver hat on to find cheaper ways of building a light.

My first step was to find a fixture to hold the COBs. I just so happened to have a dead six-bulb T5 fixture that the guts were rotted out by hanging over a salt water tank.



I gutted it and had a nice base to design around.



My first cost savings is to go with smaller heat-sinks and use active cooling. I went with 5" x 4" sinks from heatsink.com. To connect and mount the heat-sinks I went with those cross members used for suspended ceilings. I think they cost about $1.50 each.



I cut to length and notched one end to straddle the lip on the fixture to support one end.

What cobs did you decide to use Roach?

I drilled and tapped the cross-members to the sinks.

I opted to go with what I thought was the best bang-for-the-buck COB...the Cree CXA 3050's....for $12.50 each it fit into the budget....with the option of upgrading in the future.

I didn't cheap out on the driver though. I went with Meanwells HLG-185H-C700A for each set of 4 COB's. I think they came in at around $140 with shipping.

I bought some 70 mm low-profile fans to mount on the COBs. I was very fortunate that they could be screwed down onto the heat-sink easily.



Mounting the COB's were another story surprisingly enough. I had used the Ideal mounts everyone has been using for the 3070's and 3590's but found the very similar mount for the 3050's were challenging at best as the COB would not lock in, and I didn't like how the wires went into the mount.

I called Newark Element 4 (they are great!) and they suggested going with this two piece mount:


They proved to be a pain in the ass too. I just didn't like 'em.

So I made my own mounts using screen holders for screen doors.



It worked so well...no soldering and holds the COB perfectly.

I used a Wii power supply for the 12 volt stuff. It worked perfectly.

So....here's how it's shaking out now.









I'm nearing the end of this build.....It's been great fun and I am already in the planning stages for the next light.

Oh....and the cost came in at.......$506

How well are the fans cooling the sinks?
I see two fans that blow indirectly or maybe exhaust out?
Could you elaborate on this?
Also what was the cost of your parts?
Looks great with using that Used housing!

Right on with the terminal strips, that's how I started out building them!

My only concern would be the heat sinks aren't in the airflow. You might want to take some thermal measurements at the cob test point to make sure they aren't running too hot.

lilroach said:

I drilled and tapped the cross-members to the sinks.

I opted to go with what I thought was the best bang-for-the-buck COB...the Cree CXA 3050's....for $12.50 each it fit into the budget....with the option of upgrading in the future.

I didn't cheap out on the driver though. I went with Meanwells HLG-185H-C700A for each set of 4 COB's. I think they came in at around $140 with shipping.

I bought some 70 mm low-profile fans to mount on the COBs. I was very fortunate that they could be screwed down onto the heat-sink easily.

View attachment 3536564

Mounting the COB's were another story surprisingly enough. I had used the Ideal mounts everyone has been using for the 3070's and 3590's but found the very similar mount for the 3050's were challenging at best as the COB would not lock in, and I didn't like how the wires went into the mount.

I called Newark Element 4 (they are great!) and they suggested going with this two piece mount:

View attachment 3536571
They proved to be a pain in the ass too. I just didn't like 'em.

So I made my own mounts using screen holders for screen doors.

View attachment 3536572

It worked so well...no soldering and holds the COB perfectly.

I used a Wii power supply for the 12 volt stuff. It worked perfectly.

So....here's how it's shaking out now.

View attachment 3536574

View attachment 3536575

View attachment 3536576

View attachment 3536577

I'm nearing the end of this build.....It's been great fun and I am already in the planning stages for the next light.

View attachment 3536578

Click to expand...

Temps at the mounts is just above room temps.....77-80 degree-ish

I like how the diamond plate gives it that authentic red-neck seal of approval vibe. LOL C'mon on now, did you really think no one was gonna call on the DP?

Actually I like the job you've done, bravo on re-purposing an old T5 box and the Wii supply and showing for folks how simple it really is to build a quality LED grow light but don't you think the diamond plate adds too much weight? I'd mount the drivers to the box and run it without the DP or just have a sheet of aluminum cut for it but that's just me. I also like those mounts but those wires peeking out from under them and touching the LES on the COB are freakin' me out man LOL

Reflectors?

I think I would be a bit worried about those screen door clips melting and causing problems.
Great build though

The diamond plate is actually pretty thin/light. I'm actually on the fence about putting it in as right now I feel I may have a little tweaking to do and the plate will be in the way.

Cost List with links:

T5 fixture: $40 I bought it for the bulbs and it sat in my basement for about a year.

( Heat Sinks: $62.60 with shipping. http://www.heatsinkusa.com/4-230/

( Cree CXA 3050's: $116 with shipping (I got them at $12.50 each) http://www.newark.com/cree/cxa3050-0000-000n00w235f/led-hb-xlamp-cxa-warm-white-5477lm/dp/73W9183

( Ceiling grid cross-members $11 at Lowes http://www.lowes.com/pd_62262-61-XL7328RWH___?productId=3036694&pl=1&Ntt=ceiling grid

(2) Maxwell HLG-185-C700 A drivers $141 including shipping http://www.onlinecomponents.com/mean-well-hlg185hc700a.html?p=45051489

(1) 3'x3' Diamond plate It was $30 at the store http://www.homedepot.com/p/MD-Building-Products-36-in-x-36-in-x-0-025-in-Diamond-Tread-Aluminum-Sheet-in-Silver-57307/203930831

Wii power supply free

(1) Aluminum bar stock (used to hold cross members/COBs in fixture not shown) $10 http://www.homedepot.com/p/Everbilt-1-in-x-48-in-Aluminum-Flat-Bar-with-1-8-in-Thick-801927/204274000

( 70 mm low profile heat-sink fans $56 http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=4245790&CatId=494

(2) 120 mm case fans $12 http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1862464&CatId=494

Misc stuff (screws, wire, terminal strips, wire shrink wrap, beer, etc) $25ish

Total: $516

When I quoted $506 I forgotten the aluminum bar stock. The smiley faces are supposed to be "eight" in parenthesis.

p4id said:

I think I would be a bit worried about those screen door clips melting and causing problems.
Great build though

Click to expand...

That was/is certainly a concern of mine too. I had built another concept light with the same COB and shot temperatures there and now with this light. Amazingly temperatures of the area directly around the COB and even the mounts were room temperature. I can touch the heat-sink right up to the COB and it's cool to the touch.....cool I tell you....cool.

It could be because I'm using lower-powered COB's that just don't get hot. I have nothing to compare it to as this is the only COB I've used. Maybe someone using the 3070's or 3590's can chime in and tell us what temps they are experiencing.

Here's my ugly concept light that my intent was just to get a feel for this type of lighting. I had used a computer power supply and boosters to run the lights and mounted it in my existing HID hood. I think I spent all of $150 for the whole thing because I had a ton of computer parts laying around (I'm a computer tech).





I look at this as my "rat-rod" of lights......and yes...those are gutter pipes which is why I call this my gutter light.

Here's the set-up I made to hold the free end of the sink/crossmembers onto the fixture. There's three of these across the length of the fixture:

As you can tell I like "thinking out of the box" when contemplating a light-build. While not as pretty as the amazing lights other's have built and shared on here, my plants (so far) have not noticed how cheap I am.

I have two flower rooms one is still under the HPS's that will be replaced if things go well with growing under the COB LED's. Going with the diamond plate motif I may make my next build out of the lid of a truck work box like this:



This one was on Craigslist for $50. I need to cover a 4'x8' area and eye-balling this I think it'd work pretty well. I may not even need heat sinks if I do it right.

I would probably go with the CXB 3590's or 3070's for that build.....and a boat load of them to boot.

And today it's finished:



I had an absolute blast building this light. My brain certainly needed the mental exercises I put it through figuring out how to make a good light with a limited budget.

I stand in this room and cannot imagine it being brighter with the more powerful 3070's and 3590's....I'm sure they are.....but holy shit it's like I have noon-day sun blazing everything in the room.

Now I wait. I'll have the room filled with 8 plants in the next few weeks and am excited and hopeful that their growth will be equal to the HPS's these replaced.

Thank all of you for taking the time to look over my build. If there's any questions, please feel free to ask.

Lilroach, if I could give you a reputation point for this thread I would give it to you,

lilroach said:

I'm hesitant about starting my own COB build thread on here as there's many builders I consider experts here in RIU. There's amazing lights that someday I hope I can equal to the degree of quality and detail of Supra, Cpt. Morgan and others.

While these builds are the tops in quality and efficiency.....they are pricey......too pricey for my budget for what is a hobby build for me. My goal is to build an 8 COB (400 watt) light for around $500. Doing so has made me step away from massive heat sinks, $45 COB's and fancy gear that's used in other builds. So I had to put on my Macgyver hat on to find cheaper ways of building a light.
.....

Click to expand...

the experts are what's discouraging me lol ... I have been too busy to put in a lot of time to research the DIY LEDs, and looking at some of the DIY lights on this forum and all the various components was over whelming and I thought I just didnt have the time to make my own.... after reading your thread and the pics you have posted, I feel lack of time is a poor excuse and I should seriously start thinking about it... If I build a light its going to be a light like yours, so simple, thanks for all the links for the supplies and thanks to the DIY LED community.

@lilroach I applaud your ingenuity sir, setting a budget and making it happen. May I ask, what are the simple 2 piece connectors that Newark suggested? do you have a link for the item or a search term. thanks & keep up the great work.

Here ya go Growmau5

http://www.newark.com/te-connectivity/2-2154857-2/lumawise-led-socket-citizen-cll040/dp/55W5393

Just an FYI....there's an anchoring nub on the underside. Unless you want to drill an additional hole for it, you can do what I did and just nip it off.

Another FYI.....after running 12 hours I felt the "roach clips" and they were no warmer than the room. Home Depot has more rigid plastic screen holders, and even metal ones if you're not running wiring through it.

Growmau5 said:

@lilroach I applaud your ingenuity sir, setting a budget and making it happen. May I ask, what are the simple 2 piece connectors that Newark suggested? do you have a link for the item or a search term. thanks & keep up the great work.

Click to expand...

I've watched a couple of your videos growmau5.....you were in part my inspiration to take on this project. Thank you.

good job. love the gutter light.. LOL im sure the cobs do just fine. My vero 18s do great.