Cree XP-G LED Questions - First DIY Array - The Planted Tank Forum
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post #1 of 16 (permalink) Old 10-04-2011, 02:58 AM Thread Starter
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Cree XP-G LED Questions - First DIY Array

I'm looking to do my first DIY LED array for an ADA 60F Riparium (24x12x7) build and have a few questions.

The Cree XP-G LEDs from RapidLed seem to be popular I and wanted to know what "3W LED with 3,700-5,000K color temperature" in the specs means. Does the color temperature change with dimming?

I'll be growing high light terrestrial plants and a few low light aquatic plants. Light penetration is less important because the tank is only 7 inches deep and most of the water will be covered with plants and frog bit. Can anyone recommend an appropriate number of LEDs?
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post #2 of 16 (permalink) Old 10-04-2011, 03:42 AM
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The Leds come from 'bins' which are leds that all match to a certain degree. Every led is different, even if made to be the same. One neutral white, for example, could have a temperature of 4000k while another nw could be 5000k. The spectrum can shift slightly when dimming, but the amount is probably negligible for our uses.


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post #3 of 16 (permalink) Old 10-04-2011, 02:38 PM Thread Starter
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Thanks! That is quite a temperature shift from LED to LED. Would the CREE XM-L T6 3W LED (5000 - 8300k) or the CREE XP-G R5 Cool White 3W LED (5000 - 8300K) be a better choice then? This is going to be a small unit so price per LED is somewhat insignificant.
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post #4 of 16 (permalink) Old 10-04-2011, 03:25 PM
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Go with the XP-G R5's and a dimmable driver ( meanwell ELN -60-48P). 12 leds should provide more than enough light for your needs.
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post #5 of 16 (permalink) Old 10-04-2011, 03:33 PM Thread Starter
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Quote:
Originally Posted by O2surplus View Post
Go with the XP-G R5's and a dimmable driver ( meanwell ELN -60-48P). 12 leds should provide more than enough light for your needs.
What is the difference between the Mean Well ELN-60-48P and the Mean Well ELN-60-48D?
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post #6 of 16 (permalink) Old 10-04-2011, 03:43 PM
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different dimming types I guess. The P versions use a PWM dimmer, so if you have a reef controller, you can hook it up to that to do on the fly dimming and other features (sunrise/set, lightning, etc).

The D version I'm guessing you need to build a manual knob (not sure, never used D only P)


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post #7 of 16 (permalink) Old 10-04-2011, 04:39 PM
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You want the D unless you are using a digital controller. A potentiometer will be used as a dimmer knob. I suggest buying the 12 XP-G LED kit, as it will come with everything you need and save a few bucks.

http://www.rapidled.com/servlet/the-...ium-LED/Detail

Edit to add that you will need a 10V AC adapter and a potentiometer if you order the kit.
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post #8 of 16 (permalink) Old 10-04-2011, 05:56 PM Thread Starter
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Thanks everyone- just picked up the following.

1 Drilled and Tapped 4.25" x 23" Heat Sink for 36 LEDs
12 CREE XP-G R5 Cool White 3W LED with 65 degree White Lens
1 Mean Well ELN-60-48D dimmable driver
1 2 LED Moonlight Kit
1 10K Ohm Linear Potentiometer
1 10V AC Adapter
1 7 Function Multimeter
1 DC Power Connector
1 Thermal Grease (5g)
1 Y-shaped Hanging Kit
2 Wire Connectors/Nuts
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post #9 of 16 (permalink) Old 10-04-2011, 06:06 PM
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I can say for certainty that there is no discernible color change in the vast majority of LEDs when you dim them, unless you grossssssssly overdrive them (then they turn "angry blue" and then usually pop soon afterward).


I've watched Cree XPG, XPE, XRE..... Rebel.... Bridgelux...and import "chinese" ebay LEDs...... on a spectrometer with the entire light spectrum graphed out in real time as we took spectral readings for them.

Regardless of the current level, the spectral output (the ratios) remained remarkably constant. Meaning, the graphs maintained the same basic shape very, very, very well.

See this graph on a Cree XML for instance, from 700mA to 3,000mA.




Quote:
Originally Posted by IWANNAGOFAST View Post
different dimming types I guess. The P versions use a PWM dimmer, so if you have a reef controller, you can hook it up to that to do on the fly dimming and other features (sunrise/set, lightning, etc).

The D version I'm guessing you need to build a manual knob (not sure, never used D only P)

Many Reef controllers like the Reef Keeper Lite and Elite (with the ALC module) do not use PWM but rather use 0-10v analog.

Rapidled.com sells a nifty pre-programmed PWM controller for a complete dusk/day/dawn cycle built into it. Very nice. Not cheap, but awesome.

Quote:
Originally Posted by h2oaggie View Post

Edit to add that you will need a 10V AC adapter and a potentiometer if you order the kit.


The nice thing about the Meanwell is that you really only need (at the most) a 6-volt power adapter (DC). The Meanwell has an internal plastic screw labeled SRV2 that can be adjusted to change the final current output.

Meaning it's entirely possible (which I have done on 5 different Meanwells) to use a 6-volt scrap cell phone charger and still get a solid 1,000mA out of a Meanwell.


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post #10 of 16 (permalink) Old 10-06-2011, 03:59 PM
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redfishsc, the controller you're referring to, is it the DIM4? I am curious to know if it has an override to turn on LEDs manually?


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post #11 of 16 (permalink) Old 10-07-2011, 01:51 AM
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redfishsc, the controller you're referring to, is it the DIM4? I am curious to know if it has an override to turn on LEDs manually?
I'm not entirely sure but I think it does. I've never used one (nor seen one in person) but I think I remember reading a statement by Rapid that you could manually fiddle with it.


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post #12 of 16 (permalink) Old 10-07-2011, 01:52 AM
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BTW, it's THIS controller, and it's designed to work specifically with Meanwell ELN-60-48P models (that "P" on the end is an ABSOLUTE, do NOT get any other model for use with this dimmer).

http://www.rapidled.com/servlet/the-...troller/Detail


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post #13 of 16 (permalink) Old 10-07-2011, 02:56 AM
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Oh, I got the wrong controller in mind. The one I was referring to was the one sold by Ledgroupbuy (DIM4). It can be used without a controller up to 12 CREEs (XP-G and something else) with minimum of 3.

Edit: I just found out that I misunderstood the capability of the dim4. 3 per channel only


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Last edited by reybie; 10-07-2011 at 05:25 PM.
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post #14 of 16 (permalink) Old 10-08-2011, 01:16 AM
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Ah, this one. http://www.ledgroupbuy.com/dim4-4-po...ntroller-v1-0/

Yes, this one will dim anything that requires 0-10v analog dimming, but I am not sure if it has a quick override to turn on the LEDs. Milad may see this post and answer it, but if not, just send him an email, he's a good guy to do business with.


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post #15 of 16 (permalink) Old 10-08-2011, 02:26 AM
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hey Reybie, if you're curious about the manual on thing (which i know you are because you've asked on a few threads), just email them, they get back to you in less than 24 hours! very nice guy!


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