arioch's custom LED fixture

[arioch]

First, a picture of the underside of the nearly finished fixture:

 

 

This is basically a first attempt at a complete fixture, so there's a lot of mistakes and blemishes on the final product.

 

For example, our LED star pcbs kept falling off despite thermal epoxy, we figured it was due to some extremely strong shearing, which we resolved by mounting the aluminum plate on risers in the fixture casing.

 

The aluminum plate we got (scrap piece) is 12"x5" when we really could have used 14"x5" ... the tank is 16"x8" so we really needed the extra length on the plate.

 

Components:

 

LEDs:

 

5x CW Cree XREs

5x RB Cree XREs

80 degree optics

 

Drivers:

 

2x external dimming 700mA buckpucks (I may swap in a pair of 1A pucks)

2x 5K Ohm linear taper pots from Radio Shack

 

Power supply:

 

DC 24V, 3A

 

Casing:

 

Custom cut and self-drilled black acrylic, shiny on one side and matte finish on the other, welded together

 

Right now all the LEDs are thermal epoxied and/or thermal pad adhered to a 12"x5" aluminum plate, which is waiting on a heatsink from HeatsinkUSA that I will thermal paste and clamp on to.

 

TODO:

 

Drilling out the sides to provide air holes

Drill lid piece acrylic and attach a fan fixture (from Newegg, an encased fan meant for internal computer hard drives)

Maybe another acrylic job to mount the fixture over the tank

 

I've been working on this fixture for a while with a friend who got me into the saltwater hobby.

 

To follow:

 

FTS and other pics of the fixture in action

 

Thanks to my friend and also evilc66 and others who answered my dumb newbie questions in the Lighting subforum!

[arioch]

FTS

 

 

Sideways

 

[arioch]

Additional commentary:

 

I had a huge problem initially mounting the aluminum plate in the fixture, where I'd scrape off the LED domes on the CREEs. I solved this by scraping off all of the silicone used as filler between the domes that fell off and the actual diode underneath, and putting in a drop of Norland 61 (which was the recommended material from another LED diy forum that deals mostly in bicycle lights) which cures completely clear with UV exposure and doesn't craze the LED dome which I put back on top of the diode + Norland 61.

[arioch]

I'm going to borrow a PAR meter tomorrow and run some tests, but my custom-cut heatsink should arrive tomorrow as well, so I may just pull the trigger on getting a pair of 1000mA buckpucks to swap in at that point.

 

It'll be an interesting experiment to see what kind of readings I get in the tank between 700mA and 1A.

 

I'm feeling pretty good about what the light is like now and my stocking anyway, however. I have a T. crocea clam in there that looks happy as a clam at the bottom and about the only thing I want to add in there that's not in there already in terms of decent lighting needs is an encrusting monti (something like a superman).

[arioch]

Ok, so I've got 2 buckpucks (700mA, 5 LEDs per puck) wired up in parallel to a 24V 3A supply.

 

How would I go about hooking up 2 DC-powered fans (3.12W input, 0.26A rated current, started voltage 6V/7V max) maybe in series but parallel to the pucks?

 

This is the fan I've got a couple of. I'm going to bolt them to either the acrylic lid or the heatsink, not sure yet.

 

http://www.newegg.com/Product/Product.aspx...N82E16811999152

[arioch]

New plan:

 

Going to make this little gadget http://www.heatsink-guide.com/content.php?...t=control.shtml and wire it in line with the above 2 fans in series.

[arioch]

Cut up a 6x18 Bergquist thermal pad to fit on the 5x12 heatsink, so now the heatsink is affixed to the aluminum plate. Still waiting on the thermistor (not available from Radio Shack anymore!) in the mail before I can finish up.