# DIY LED question



## popomon (Oct 12, 2010)

Hey guys, its been a while since I've been on and such, but I finally came back :. I was thinking about building a custom led fixture for a larger tank in the future, but I've ran into a small problem that I can't seem to understand. Do these meanwell power supplies; http://www.rapidled.com/servlet/the-51/Mean-Well-LPC-dsh-60-dsh-1050-constant/Detail adjust to the voltage needed automatically? Because they say that there output range is 9-48Volts, but I don't know if Im supposed to change something in it or if it somehow auto detects the needed number of volts (for example, the difference between running 9 X 3W LEDs or 12 X 3W LEDs, etc.) I plan on making a fixture hooked up to 24 3W XP-G LEDs, but I need to get over this barrier first. I am planning on using 2 of these power supplies, but I need to make sure that I don't overpower or underpower the LEDs. Thanks in advance, I know APC won't dissapoint 

EDIT: I understand that these power supplies deliver 1050ma while the max current running through the XPGs is 1500ma, considering they run at 3.3v, would 1050ma be enough to power them efficiently? I don't understand the point of labeling them as 3W LEDs when they have potential to reach 4.5-5ish Watts. And I would be satisfied running them at 1050ma since 3Watts per LED is plenty for me, I just wanted to know. Sorry Im so hard to understand, Im terrible at explaining things haha.


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## cath0de (Feb 23, 2011)

I gave the datasheet a quick look. I think you might want to keep looking for a different driver. I see no way to adjust the brightness of your leds without additional circuitry. You could email Mean Well or Rapid LED and tell them what you want to do. I might be missing something in terms of how this driver works but it only has two wires going in and two going out. Even if it can autodetect and adjust the voltage you won't have any control over brightness. Sorry I can't be of more use.


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## popomon (Oct 12, 2010)

welll, controlling brightness wasn't too much of a problem. I actually went over to reefcentral (i know, i know) and they have much larger banks of knowledge in this kinda stuff. I was just wondering if any of us plant guys had any input. If I cant get this working or a smaller scale model than I will definately post haha


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## IwannaGoFast (Jan 11, 2011)

I used these drivers on my tank, they are not dimmable. The light is very bright. I'm not sure how they split the power between the LEDs though. 

The light is too strong for a planted tank with optics, and without, the spread is so wide that most of the light hits the glass and I was dealing with GDA almost every day.

What I ended up doing was switching to the meanwell dimmable drivers, and I put 60 degree optics on the LEDs, I turned the power down to about 50%. I still get the same amount of PAR but the light isn't shined on the glass so I don't have to deal with algae, and with the optics, the shimmer is a lot better.


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## popomon (Oct 12, 2010)

Well, i was planning on building a hanging ballast with 40 degree optics. DO you think that would be good? About a foot off the tank top. And I could go without optics too closer to the top, I would just make some reflectors to keep it more centered. Considering you built an LED fixture already i'd appreciate your input. thanks!


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## IwannaGoFast (Jan 11, 2011)

what size tank? if you do 40 degree optics, you'd have to mount it pretty high off the tank to get a spread that'll cover the whole tank.

mine w/ 60 degree optics is hung amoust 2 feet off the tank, other wise the light doesn't spread. Good thing though is even at this height, you'll still get plenty of light.

If you want to hang it a little lower, there are 80 degree optics too.


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## popomon (Oct 12, 2010)

well, I plan on having 1.5 to 2 inch spacing between each led. So that might contribute. Also, i can clump them tighter if need be because I do plan on having active cooling and a bigass heatsink. Whatspacing do you have? Because I know that 1.5 inches is fairly close for an led setup. And again, I dont have to have optics, since im building an enclosure for it, I could put reflectors inside. I know that the crees have a 90 degree natural spread with a little bit of spill to 120 degrees right? At 1 foot with reflectors i think that would work, corect me where im wrong.


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## chunkypeanutlove (Sep 2, 2009)

with this driver you can run 12 3 w led. Dont listen to cath0de, these are great drivers. As you saw in reefcentral, they are cheap and perfect to light tanks.


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## popomon (Oct 12, 2010)

thanks for the input peanut


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