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[I was originally going to post this in the same thread as my tank, but I would like to keep the feedback together, so I am posting a new thread instead.]
I need an SPS capable light for my 48"x24"x24 tank. I am thinking DIY, although it seems like new off-the-shelf units are coming out every month and they are getting closer and closer to what I want to build myself.
While I know there is a lot of ideas floating around in terms of different color LEDs and even multi-chip LEDs, I am thinking about a typical CREE XP-E/XP-G Royal Blue/Cool White fixture. Here are my current specs:
100 LEDs
3:2 Ratio of RB:CW
60 CREE XP-E 500 Royal Blue
40 CREE XP-G Q5 Cool White
60 Degree Optics
10" wide HeatSinkUSA HeatSink
Wired in Series with Thomson Research Product Drivers
Originally, I was thinking one long heatsink laid out something like this (ignore the LED layout, this is not what I was planning):
Then I got some feedback on nano-reef.com and people said that two smaller units might give me more flexibility, so I designed this:
In this layout, I can use one TRC-120S105DT (1050mA) and TRC-120S140DT (1400mA) to drive the 30 RB and 20 CW LEDs, respectively. With these drivers, my plan would be to always have these dimmed somewhat. Technically, the 1050mA is 50mA too high for the XP-E 500 RB. Here is roughly how it works out:
XP-E 500 RBs at 1000mA run at 3.479V, so 30x = 104.37V. The TRC-120S105DT has a voltage range of 68-114V, so I should be OK there.
XP-G Q5 CW at 1400mA run at 3.528V, so 20x = 70.56V. The TRC-120S140DT has a voltage range of 52-86V, so I should be OK there too.
With the 60 degree optics, I looked at getting these spreads with the light 12" above the tank. These diagrams show the 60 degree overall spread and 30 degree spread that contains most of the light from the LEDs:
Most recently, however, I saw that nanocustoms is going to offer the following heat sink Kit and a DUO700 driver box, so I could build four of these and run them at 700mA instead of 1000mA and 1400mA.
If I wanted to use the Duo700 driver box, it would limit the build to 700mA -- not sure I want to do that -- but the math works out like this:
XP-E RB 500
LEDs Amp V Each Total Volts Total Watts
15 0.7 3.4 51.0 35.7 </p>
<p>XP-G CW R5
LEDs Amp V Each Total Volts Total Watts
10 0.7 3.242 32.42 22.694
This gets me back to my original 100 LEDs but running at 700mA. Of course, I don't need the Duo700 box, so I can drive them in series with different drivers and drive them higher.
I do not believe that was a heat sink.
I believe that was a block of aluminum carved into a custim heat sync.
You could get something like this carved into a heat sync, call around to some machine shops.
Maybe a hobyest on the board can help.. I have a mini mill.. no skills at all but I have one. I keep it in the backroom of my gunshop.
Couldn't be too hard.. spend some time laying it out clamp it down and cut away what doesnt loo right...
There is even a machine shop club you can join for doing exactly this kind of projects. I forget the posters name but they just posted a DIY of a very nice frag rack built at this same machine shop club.
I could machine it for you but you won't like the prices. The materials alone will run you over $500 plus shop time. 24x24 is a large size and price/increasing thickness is highly disproportional. I suggest going with multiple strips and daisy chaining them together to keep prices down. Otherwise, if you really really really want a custom heatsink, and are willing to pay the prices, I could do it
This is the heat sink I am thinking about. Can a machine shop simply carve out a pattern for the fan? Is that a lot of money?
10" Profile Heat Sink, 21" Long
its more expensive than its worth the trouble to be honest. I would just take a dremel to it
I bought my heatsinks there, and have been fairly happy.
The only downside, they are heavy.
Another good reason to have multiple smaller sets.
I have a metal hand grinder if you want to remove a lot of aluminum fast for the fan.
(Union City)
Note that you might need a different type of fan if there is no space below it.
--
A note on those drivers: You are going to a pretty high voltage.
That does save time and effort, and can improve efficiency.
However, it gets rid of one key advantage of LEDs - safety.
Once you head up into the 100V range, you need to think about insulation, and
what can happen when things go wrong. I have certainly heard plenty of stories about
shorts between LED star and heat sink online.
TechShop and do it yourself.
You can also pay the people there to program the machine for you. Don't expect it to be as cheap as the extruded heat sinks though.
Well, two things.
First, a lot of DIY projects are way overkill on heat dissipation via heatsinks... trust me, you don't need THAT much but it certainly won't hurt, so don't consider it a requirement.
Second, extruded aluminum will be far cheaper than a machined block of aluminum, which is what nanocustoms/tuners/etc is. For your project I imagine HeatsinkUSA is a good bet... they make what you probably need out of extruded pieces, in custom lengths. Put it in an enclosure if you want it to look pretty. 
Just a hand held router? I don't have one, but will an inexpensive one work or do I need a fairly high-end router to cut through metal?
if I wanted to find someone who could cut a similar pattern to the heat sink above into a 21" heat sink, where would I look?
-Ray
120G Custom ZeroEdge