Building COB LED Fixture - The Planted Tank Forum
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post #1 of 8 (permalink) Old 10-10-2020, 05:18 AM Thread Starter
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Building COB LED Fixture

Hello,

I'm piecing together ideas for building a fixture for a 10 gallon. I've done 3w stars in the past, but for the cost, output, less wiring/soldering I'm looking at COB's this time.

My idea that I've gathered from reading threads lately has been to use 3 976-BXRE-65S1001-C-74-ND and 2 L2C5-30901204E13C0 or 2 BXRE-50S1001-C-74. I'm not 100% on the spectrum I would prefer at the moment, I'm thinking I would prefer a more neutral white tone than warm. To start off, I might go full Bridgelux because of the price being lower than lumileds.
Drivers will be one LDD-350HW per COB,
350 watt 48 volt power supply, (from a previous build)
Heatsink will be 17" x 7.984" Wide Extruded Aluminum Heatsink with two 120mm fans mounted above it.
Controlled by a modified TC420.

The layout that I'm looking at is 1 V10C THRIVE left right and center with the crisp whites to the left and right of the center LED spread evenly between the V10C THRIVE's. All centered on the heatsink's width using thermal LED mounting tape.

I want to have a splash guard with some kind of frosted light diffuser added such as this one Rosco Cinegel Silent Frost. The reason for the light diffuser is that this fixture will be hanging, and I don't want to be blinded by a direct view of the COB's every time I look at the tank.

So my questions are:
Are the 350mA drivers going to give me enough output? I don't need extreme par, but I would like to have some room if I want to go there. If I'm underestimating the mA relationship with COB's would going lower to 300mA be better? From what I can see the lowest LEDSupply offers is 300mA LDD-HW's .

Is the heatsink and fans going to be adequate for the 5 COB's I've chosen?

Will the film be too frosted, or should I go with a more transparent version.

Thanks for the input.

Last edited by Quesenek; 10-10-2020 at 05:57 AM. Reason: Edited post
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post #2 of 8 (permalink) Old 10-10-2020, 08:13 AM
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Each COB is roughly equiv to 4 "3w" emitters you have used in the past.
Adds perspective.

You may want to consider strips instead for a 10 gal.

https://www.google.com/url?q=https:/...OcFWJ4QC2-yyIY
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post #3 of 8 (permalink) Old 10-10-2020, 11:01 AM Thread Starter
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Quote:
Originally Posted by jeffkrol View Post
Each COB is roughly equiv to 4 "3w" emitters you have used in the past.
Adds perspective.

You may want to consider strips instead for a 10 gal.

https://www.google.com/url?q=https:/...OcFWJ4QC2-yyIY
Thanks for the input and the equivalence of the stars to COB's.
I'll have to keep the strips in mind, the main thing I like about the COB's are that they come in a 6500k version, and the spectrum chart looks like it has nice peaks, with 95 CRI among the different color temperature versions according to the specs.
I realized that I posted the wrong COB's I meant to put the V13c's in there, but it's probably not that much of a difference at 350mA. At a glance, running them at 350mA would equal out to around the same lumens according to the datasheet.

I'll go back to the drawing board to figure out what I need with the fixture with the equivalency in mind. Last time I had a 10 gallon set up I was running 14 3w stars and it grew plants fine at around 50% power or less IIRC might just rebuild that fixture TBH.
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post #4 of 8 (permalink) Old 10-10-2020, 11:00 PM
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Quote:
Originally Posted by Quesenek View Post
Thanks for the input and the equivalence of the stars to COB's.
I'll have to keep the strips in mind, the main thing I like about the COB's are that they come in a 6500k version, and the spectrum chart looks like it has nice peaks, with 95 CRI among the different color temperature versions according to the specs.
I realized that I posted the wrong COB's I meant to put the V13c's in there, but it's probably not that much of a difference at 350mA. At a glance, running them at 350mA would equal out to around the same lumens according to the datasheet.

I'll go back to the drawing board to figure out what I need with the fixture with the equivalency in mind. Last time I had a 10 gallon set up I was running 14 3w stars and it grew plants fine at around 50% power or less IIRC might just rebuild that fixture TBH.

Keep in mind some cheap stars can have efficiencies in the 40-60 Lumens/watt
some COBs/quality LEDS approach 200 Lumens /watt
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post #5 of 8 (permalink) Old 10-11-2020, 02:00 AM Thread Starter
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Quote:
Originally Posted by jeffkrol View Post
Keep in mind some cheap stars can have efficiencies in the 40-60 Lumens/watt
some COBs/quality LEDS approach 200 Lumens /watt
My previous builds have used the luxeon rebel and sunplus LED's with the exception of the UV's that were just standard no name LED's.
Initially, I was looking at just building a SBReef copy with the no name LED's, however the data that the sellers provide just says lm = 100-110 with no indication on if it's lm/w or just that many period while still taking the 3w of power and generating the heat of something much more powerful in the equivalent wattage.

While thinking about it before I jump headfirst into this, I might grab 2 of the thrive v13c cobs (Thinking 6500k and 5000k for a cooler neutral tone) and run them as a kind of point light pendant for a test to see where I need to go, if I need to add more or if the 20ish+ watts of light is enough for what I'm after with the tank. Ideas keep changing not thinking any red plants so par really isn't that big of an issue, but I do want high CRI for the "look" that my previous 10 gallon build gave with around 92-93 CRI compared to say the SBReef's that really don't deliver the same feel despite developing good colors in the plants.
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post #6 of 8 (permalink) Old 10-11-2020, 02:12 AM
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Quote:
Originally Posted by Quesenek View Post
Hello,

I'm piecing together ideas for building a fixture for a 10 gallon. I've done 3w stars in the past, but for the cost, output, less wiring/soldering I'm looking at COB's this time.

My idea that I've gathered from reading threads lately has been to use 3 976-BXRE-65S1001-C-74-ND and 2 L2C5-30901204E13C0 or 2 BXRE-50S1001-C-74. I'm not 100% on the spectrum I would prefer at the moment, I'm thinking I would prefer a more neutral white tone than warm. To start off, I might go full Bridgelux because of the price being lower than lumileds.
Drivers will be one LDD-350HW per COB,
350 watt 48 volt power supply, (from a previous build)
Heatsink will be 17" x 7.984" Wide Extruded Aluminum Heatsink with two 120mm fans mounted above it.
Controlled by a modified TC420.

The layout that I'm looking at is 1 V10C THRIVE left right and center with the crisp whites to the left and right of the center LED spread evenly between the V10C THRIVE's. All centered on the heatsink's width using thermal LED mounting tape.

I want to have a splash guard with some kind of frosted light diffuser added such as this one Rosco Cinegel Silent Frost. The reason for the light diffuser is that this fixture will be hanging, and I don't want to be blinded by a direct view of the COB's every time I look at the tank.

So my questions are:
Are the 350mA drivers going to give me enough output? I don't need extreme par, but I would like to have some room if I want to go there. If I'm underestimating the mA relationship with COB's would going lower to 300mA be better? From what I can see the lowest LEDSupply offers is 300mA LDD-HW's .

Is the heatsink and fans going to be adequate for the 5 COB's I've chosen?

Will the film be too frosted, or should I go with a more transparent version.

Thanks for the input.
Hi @Quesenek,

If you want to go the easy route you might check out this thread. -Roy
https://www.plantedtank.net/forums/1...ted-tanks.html
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post #7 of 8 (permalink) Old 10-14-2020, 09:06 PM
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Whatever you decide to go with COBs or strips you should write up a build in here

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post #8 of 8 (permalink) Old 10-15-2020, 07:35 AM Thread Starter
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Quote:
Originally Posted by monkeyruler90 View Post
Whatever you decide to go with COBs or strips you should write up a build in here
Yeah, I'll update it with what I have going when I build it.
I decided to go with a thrive v13c 5000k and a lumiled 1204 crisp white gen 2.
We will see what happens for plant growth, I don't expect much par out of these COB's alone, but the initial test should come close to my 3 watt diode setup I've used in the past and those grew plants great at only 25-40% (I didn't know that the par was probably really low).

What I'm more interested in seeing is how the plants respond to the 5000k thrive COB spectrum along with the violet peak in the crisp white COB.

It's worth noting that this fixture is likely going to go over the waterbox clear mini 6 instead of a standard 10 gallon as I had originally planned. I've got a ton of ideas floating around of what I want for a new tank and decided since I already have a 55 gallon that I don't want anything too large.

Edit:
Got the chips in.

I haven't been able to test both together because LEDSupply sent me the wrong LDD driver, so I'm in the process of getting that fixed.
I tested both individually. The 3000k crisp white is as expected more of a white-yellow/orange however it doesn't discolor the greens like my 4000k's would. It adds a nice warm neutral white tone to the tank while also making the plants pop.
The Bridgelux thrive v13c 5000k is nice; it doesn't wash out the plants despite being an extremely bright neutral white light, quite the opposite really, the plant coloration is rich under the light.
I've forgotten what high CRI whites look like on a tank, at 90 CRI for the lumiled and 95 on the bridgelux the plants display much more detail when compared to a nicrew classic plant light (one with the pinks and the greens) that is normally on the tank.

While going through the process of ordering the heatsink I realized that for the price I would be paying to build everything custom it was going to be cheaper to go with a slim MakersHeatsink kit. I'm glad I did, installation of the LED's took 2 minutes, got the 12" fixture for the waterbox clear mini 6 and after 3 hours of testing the temps, the fixture was only slightly warm to the touch around the diode.

Last edited by Quesenek; 10-18-2020 at 01:56 AM. Reason: added
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