DIY LEDs - The write-up

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chathaway417,

I just built a very simple Arduino dimmable circuit following kcress' directions, a very easy circuit to understand and build. This is the thread where I asked questions and received guidance:
http://www.reefcentral.com/forums/showthread.php?t=1914090

Arduino model was Duemillenove, similar to the current Uno.

It is probably a less expensive build than the other ones I've seen around, and probably also simpler to build. Of course, it is probably less efficient...

Take a look at the thread, it might give you some ideas.

Snorkeler
 
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I need input from you guys. I'm helping a friend to design and build a lamp for a 900g tank. Is currently lit by four 400W radiums on lumenbright reflectors but he wants to use MH's for 6 hours and complete the whole photoperoid with LEDs. That means we want a strong light and not just strips or weak supplement.

The space available is very limited. Just about 6" x 16" between each reflector but spot lightning will be a problem. Each relefctor is more than 20" diameter. There's an angled wall in the front of the tank which is 9' long and allows to use long heatsinks to have a more even light source. The problem is this wall is very close to the water surface and heatsink will have to be well enclosed and I'm not sure if we can fit fans over the heatsink. There is a big Lasko fan blowing from the side of the tank so the area is well ventilated though. This wall provides space to fit a 5.35 profile heatsink x 9' long so two pieces of 48" can be used. Each piece holds up to 78 LEDs with 2" spacing between LEDs and rows.

Here's a pic of the available space were the Current moonlights are now
018a-1.jpg

Another shot with the fan
021sv-1.jpg

And the proposed 4' Heatsink with 3 rows of 26 LEDs
Thinking a mix of XPG-CW, XRE-NW, XRE-RB
That would be close to 156 LEDs total.
Not sure about optics though. The tank is 3' tall so we may need tight optics to get to the bottom but don't want to see a lot of beams like lasers
miguel.jpg
 
Looks ok to me. I don't see why you want to keep those heaters though.

I don't see how you're not going to occlude the MHs with the heat sink. Plus you're going to have the LEDs in the splash zone.

I'd ditch the MHs add narrow optics and raise the LEDs about 3 feet above the tank. This would preclude the need for any protection schemes. It would punch the light to the bottom and homogenize the beams.
 
If it was me, I'd ditch the MH's but I know this is a step very close to removing the MH's and make another 8' array, change some lenses and hang it were the MH's are :lol:

Do you think is safe to have that amount of LEDs on that heatsink without a fan?
 
what type and size of screws is everyone using to attach the LEDs? How many people have used the Thermal Adhesive? What are the pros/cons?
 
I use 4/40 with a nylon washer. Pros easy to change. Cons drilling all the holes. I did not tap, but there is only 1/10 inch or so the screws (stainless) seem handle it.
 
sbleile, I drilled and tapped my first LED array and am in the process of redoing two new heatsinks. Like TheFishMan65 said, it can be a hassle to drill all those holes by hand at first, but the ease to change them afterwards is a breeze as your LED needs change.

TheFishMan65, where did you get your nylon washer and screws from?
 
sbleile said:
what type and size of screws is everyone using to attach the LEDs? How many people have used the Thermal Adhesive? What are the pros/cons?
Click to expand...

Some people don't like the adhesive in case they ever have (or want) to replace an LED. In that case, screws make things pretty easy. Initial assenbly takes more work.

Therman DIYed a spanner to fit the slots in the star that made it easy for him to simply twist the star of the heat sink. The epoxy has very poor shear strength. I popped a couple off with a wood chisel, a lot more easily than I expected. With that in mind, if you choose adhesive, clean the back of the star, and the heatsink very well prior to using that method. I have some of the pads from nantotuners that are less mess that either of the other two methods, but more expensive. I haven't mounted any LEDs with them yet, nor tried to removed them...

Tim
 
sammy113 said:
Do you think is safe to have that amount of LEDs on that heatsink without a fan?
Click to expand...

Yes but.... If you had the fixture up where you didn't need a cover. Otherwise with a protected front it's going to probably be a bit warmer then you'd want. You don't need a blasting blower though just some air movement.

I see the plan here, testing the waters, as it were. As soon as the guy sees how well optic'd LEDs penetrate he'll want to completely switching over.
 
kcress said:
Yes but.... If you had the fixture up where you didn't need a cover. Otherwise with a protected front it's going to probably be a bit warmer then you'd want. You don't need a blasting blower though just some air movement.

I see the plan here, testing the waters, as it were. As soon as the guy sees how well optic'd LEDs penetrate he'll want to completely switching over.
Click to expand...

Thanks for the input. I'm heading to his house to take a good look at the space and have some final plans drawn.
 
I am getting ready to build a 250 LED unit for a local friend. Are there any other drivers out there that can dim like a Meanwell but run a larger amount of LED's?

-Dave
 
LED upgrade

LED upgrade

Hi guys n gals. I`m finding myself at the point of a whole new lighting system. So, i`m looking into LED...and i`d like to DIY. SO, my big concern right now is that i only have about 14-16" of hieght max for the distance between the bottom of the LED fixture and my Tank to work with. I do plan on a plexie shield about 2" from the LEDs to protect them but, it`s the short distance to the tank surface i`m concerned about. I read that some folks place the LED fixture high up above the tank to avoid burning the corals but , i can`t do that. So....what can i do? Or is it a big deal? Thanks.
 
Im not sure if this has been asked before but instead of using thermal tape, why don't we use Arctic MX-3. Its the same stuff that you put between your CPU heatsink and the CPU itselfs. Its proven to be really good in the computer industry via transfering heat. So why not use like a small dot to attach it to the heatsink for better heat transfer?

Here is the product that im talking about

http://arctic-cooling.com/catalog/product_info.php?cPath=39_&mID=274
 
it has been discussed a few times. People who mount LES stars with screws use thermal compound. Others decide to glue with two part epoxy. Not all thermal compounds actually dry hard enough to hold the LEDs without any other help.
 
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