# DIY LED Array



## alip01 (2 Jun 2010)

Right guys.  I've done alot of reading about LED arrays for planted tanks, and pretty much understand it, however I've still got a few more questions, which hopefully someone'll be able to answer!

The tank that I'm planning to make the LED array for is a 30cm cube.  I'm after high light levels, so I think around 1.5W per gallon would be about right, which would be around 10W, though from the drivers I've seen, it'll be easier to use 9W.  Is it best to go with 9 1W LEDs, or 3 3W LEDs?  That's assuming the light levels will be suitable ?

Will I need to get any lenses to fit over the LEDs, or are they not really necessary?  If I do, what angles am I going to be looking at getting?

What's the best way of driving the LEDs?  I've seen links to this one, but are there any better (or cheaper) drivers that I could use?  I've looked at using other methods to power the LEDs, but they're a bit complicated for my liking.  However, if there are better (or cheaper) methods, would someone explain these to me please!

I think that's it for now, though I'll undoubtedly think of some more questions to ask!

Thanks,
Alistair


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## alip01 (8 Jun 2010)

Does anybody know about what I'm looking to do?  If not, I'll just have to go for it and hope that I'm right.


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## Zeeto (9 Jun 2010)

Hi Alistair,

I don't think that driver would be the most suitable, depending on what Led's you would be using.

Take this led for example a cree R2 http://www.led-tech.de/en/High-Power-LE ... 20_77.html

You would need a minimum of 350ma of current but 1000ma for the max output of 242 lumens.

It may be better to get a constant current circuit board like this http://www.led-tech.de/en/LED-Controlli ... 8_119.html


Regards
Matt


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## Zeeto (9 Jun 2010)

I would also use the 3w leds and use a wide angle optic with a fair distance to the water depth so you don't get a concentrated beam. It may also be worth upping the number of leds you plan to use, maybe to 4 spaced evenly over the tank surface?


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## alip01 (9 Jun 2010)

Hi Matt,

Thanks for the information.

I was planning to use some 3W Luxeon Stars such as these, but really just the cheapest ones I can find that have a good reputation.

Would lenses such as these be suitable?

Thanks again,
Alistair


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## Zeeto (9 Jun 2010)

Here are the specs for those LED's

LXHL-LW3C Specifications:
Lumens @ 700mA: 65 lm
Max Continuous Current: 1000 mA
Forward Voltage : 3.9 Vf
Dominant Wavelength: 5500 K
LED Type: Star
Radiation Pattern: Lambertian
Weight: 5.5g

65 lumens isn't very much tbh, I'm not sure however what the ideal would be for a planted tank, maybe someone with experience of led's in an aquarium will chime in. You can get 3w leds over 240 lumens as per previous link which would mean you could use less leds overall.

The optics look fine and a 60 degree will give a very wide spread, I don't think there would be any need to go for an optic with a more concentrated beam at your tank depth.

Regards
Matt


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## alip01 (9 Jun 2010)

OK, I think I'll use the Cree R2s then.  I've seen them mentioned a few times when looking at aquarium related LED lighting, so they should be good.

I've found a slightly cheaper supplier of the LEDs, who also has drivers that appear to be similar to the one that you suggested, also at a slightly cheaper price.  

http://www.ledrise.com/accessories/led- ... dd_product

The power supply says that it is for 5-8 LEDs, would it matter that I am only planning to use 4?  From what I've read, I don't think it would, as the current would stay the same, and so it shouldn't be an issue - am I right in thinking this?


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## alip01 (10 Jun 2010)

I've been doing some more research, and found these Seoul Z-Power P4 Star LED, Rank U, White, 240lm, 120Â° LEDs.

They seem to have pretty much the same specs as the Cree XR-E 7090 R2 Stars, but are half the price.  They even use a Cree LED chip, so I think I'll try them initially.

I'd like the run them at a high forward current so that I can get more light, so I presume that it would still be best to use the 700ma driver?  However on the tech specs for both LEDs, it says that the recommended forward current is 350ma, so would it be better to run them at this level?


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## Zeeto (11 Jun 2010)

Those Seoul Led's should be perfect, a good cheap high output 3W led.

With regards to which current to run the led's at, they will be most efficient at 350ma. The more you increase the current the less efficient they become and the more heat they produce. This however should not be a problem if you adequately heatsink the led's. I would def run the led's at 700ma, you should have absolutely no problem.

Regards
Matt


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## alip01 (11 Jun 2010)

Thanks for all the help Matt! Looks like I'm ready to place my order! 

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