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post #1 of 8 (permalink) Old 07-07-2011, 05:39 AM Thread Starter
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DIY LED Questions

Not sure if this is the right place for this.

I've decided to build a DIY LED light fixture for my 75 gallon aquarium. I went with 6 Cree XML cool and 6 Cree XML warm.

What power supply would you recommend to run these lights? Also, if I wanted to dim them, which dimmer would you recommend?

I'm also looking for a heatsink. I want two that are around 2"x40". Has anyone come across any heatsinks that are like this?

Thanks for the help!
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post #2 of 8 (permalink) Old 07-07-2011, 01:10 PM
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www.rapidled.com is a good one-stop-shop

www.heatsinkusa.com can cut to length, but I don't know if they have sinks that narrow.

Meanwell is a popular power supply/driver company in the hobby. Assuming you want dimming and/or color mixing ability, you'll need 2 drivers. Each capable of delivering 21vdc at 3.5 amp to drive the XMLs at their max rating. A quick glance at the Meanwell spec sheets show that a HLN-80H-24 is a good fit for those parameters. Of course, that's only one electrical scenario. If you want a different circuit layout or driving goals, you would have to seect something else.
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post #3 of 8 (permalink) Old 07-07-2011, 02:30 PM
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I use 50-50 warm white and cool white, with a different model LED, and it doesn't really look like I wanted it to look. Too many warm white LEDs. If you use neutral white LEDs instead of warm white I think you will be more satisfied. Being able to dim the two colors independently will also allow you to adjust the mix to better suit your tastes.

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post #4 of 8 (permalink) Old 07-07-2011, 02:35 PM
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I used 2:1 neutral to cool (a different brand) and think the color is about right.
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post #5 of 8 (permalink) Old 07-22-2011, 02:48 AM Thread Starter
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Thanks everyone for the help. I've been continuing my research and have run into another road block.

Assuming I buy the two meanwell dimmable drivers (HLN-80H-24, which I've read that the other common meanwell dimmable driver ELN-60-48 you cannot use less than 8 LEDs which I will have 6 XMLs on each driver) do I need to buy another component to dim the leds? I've seen a meanwell dimmer? From what I've read, you need to have at least 3 drivers connected to the dimmer, where I will only have two.

Or, can you "dim" the LEDs buy adjusting the screw that is inside the driver (adjusting the current?)?

I'd really like to finish this build soon, so I'd like to get the correct components ordered as soon as possible.

Thanks for all the help!
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post #6 of 8 (permalink) Old 07-22-2011, 04:40 AM
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What are the dimensions of the tank? If it is a standard 75 gallon tank, it is 4 feet long and 20 inches tall. If you put the LEDs in two rows of 6 LEDs, they will be about 8 inches apart. That lets you adjust the color by selectively dimming one row more than the other. But, I think you will get only about 10 micromols of PAR with that. You would need to reduce the LED spacing to 4 inches to get the PAR up to about 40 micromols, and that would require twice as many LEDs, or running them at a lot more than 1300 mAmps. But, if you do that, you need a much better heatsink. At 1300 mAmps, I believe you can use aluminum channel extrusions.

Hoppy
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post #7 of 8 (permalink) Old 07-22-2011, 11:40 AM
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Quote:
Originally Posted by aggie04 View Post
Thanks everyone for the help. I've been continuing my research and have run into another road block.

Assuming I buy the two meanwell dimmable drivers (HLN-80H-24, which I've read that the other common meanwell dimmable driver ELN-60-48 you cannot use less than 8 LEDs which I will have 6 XMLs on each driver)

Datasheet is your friend.

http://www.meanwell.com/search/hln-80h/HLN-80H-spec.pdf

Voltage output range for this is 14.4v to 24v, which means your XML's (which have a 3.5vf at 3.0 amps) can be 4-6 per driver. I'd definitely put the full 6 per driver.

Quote:
do I need to buy another component to dim the leds? I've seen a meanwell dimmer?
This one does not appear to be "dimmable" in the main sense of the word. You won't be able to easily dim it up/down to play with light intensity or anything. You'll need to look for a model ending with "D".

This model will have an internal screw that allows you to set the final current, but it's a hassle to get to if you want to dim the LEDs a lot. Meaning, you set it and forget it. And you can only go down to around 2.0amps, which is still brutally bright.

"D" models require a small voltage input that DOES NOT exceed 10v. Anything from 7-10v will work. Once you hook up your voltage (small regulated DC adapter) and a 10K potentiometer knob, you can then turn it on, measure current, and fiddle with that INTERNAL screw I just mentioned to fine-tune your current output.



Good luck finding a D model for this Meanwell model.

Quote:
From what I've read, you need to have at least 3 drivers connected to the dimmer, where I will only have two.
You're thinking of the RapidLED "pwm" dimmer. It's a specialty dimmer requiring a specific version of the dimmable Meanwell drivers (those ending with P).


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post #8 of 8 (permalink) Old 07-22-2011, 12:29 PM
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That RapidLED DDC-01 dimmer controller works just fine with a single driver. It has three channels, but all don't have to be loaded.
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