DIY LEDs - The write-up

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The star design allows efficient packing while keeping them all oriented the same. With a circle you could still pack them but it wouldn't be as neat looking or ordered.

Also I know the Carclo optics attach to a star base, not sure if the round bases have the right holes. Anybody?


That's a good point Re: fixing a fried SMT led. Would the only way to un-solder an individual die be to bring the whole board up to a temperature where the solder flows?
 
People may have seen these, and they are worth reading. Long-Term Lumen Maintenance Interesting statement that air temperature affect two item related to over all life expectancy. First how much heat can be dissipated and second silicone used for mounting degrades in heat. I read this a the lens over the LED.

We should probably all read this one since it is what we are doing (no I haven't read it yet):LED Luminaire Design Guide

Here are some more for those interested:
Solder & Handling - we aren't doing this usually
Thermal Management - dwzm already posted this one
Reliability
Electrical Overstress
LED Eye Safety - imagine that! They don't recommend looking at them. Now where have I read that :)

[EDIT]
These are for CREE, but the info probably transfer across to all LEDs.
 
ReefEnabler said:
That's a good point Re: fixing a fried SMT led. Would the only way to un-solder an individual die be to bring the whole board up to a temperature where the solder flows?
Click to expand...

With a hot air rework station you can pop off a single component, but I'd imagine it would be tedious work. And re-attaching the new LED with hot air would be an interesting challenge, since in most cases the pads (including the all-important thermal ground pad) are under the LED chip.
 
The Grim Reefer said:
The star does have a whole lot more exposed side area but I have no clue if that is as important as contact area with the heat sink. Got to be some reason they came up with that design.
Click to expand...

Reason: It looks more cool/techy. Although a person could argue that it's one of the most efficiently packable shapes if you are putting them edge to edge, I truly believe that the primary reason stars caught on is simply because of the way they look.
 
I think it also gives the end user more options in mounting orientation due to all the cutouts around the parameter of the star...
-R
 
Hello guys,

I have read up all posts in this thread. It's a very active thread and I am becoming like that :wildone: after reading the whole thing!

a) I currently own a 180 gallon tank which is has the following dimension 6'x2'x2'. The tank has 2 braces. Therefore, I have 3 opening on the top of the tank about 21.5"x21.5".

b) I want to keep mostly SPS will LPS on the bottom of the tank.

c) I have selected the following LED from Cree: Cool White XP-E P/N: XPEWHT-L1-0000-00F01 (R3 bin) and Royal Blue XP-E P/N: XPEROY-L1-0000-00A01 (15 bin)

d) From what I have read, I am planning to have 168 LEDs in three groups of 56 LEDs

e) I am planning to run all LEDs on 1000 mA constant current with my own LED driver.

f) White and Blue LED will be powered separetly serially in group of 5 or 6.

g) I currently have three 12"x13" heatsinks.

h) I am planning to used this FRAEN Lens: FCP-M1-XPE1-HRF (Medium beam - 21 degrees beam angle)
see link hxxp://www.fraensrl.com/images/Fraen-FCP-datasheet.pdf


Here my questions:
1 - What do you recommand for LED group dimension of cover 1/3 of the tank?
2 - Is 12"x13" enough?
3 - If I am using 2.5" LED spacing rule, I will need about 18"x20" heatsink to fit all LED of a group. Can the LED be closer?
4 - Is my FRAEN optics good? Or I should go with the Wide Beam which has a 39 degrees beam angle?
5 - Where do you put the LED driver? Do you put as close as possible or you can put it under the tank?
6 - What is the PWM frequency to you use to drive the LED?

In fact, I want to determine the dimension of each group of LED to avoid having dead spot over my tank and by having a design which fit 24"x24". It will be modular and it will fit for 2', 4', 6' and 8' tank. Also, I do not want to have LED under a brace which is useless.

From you comments, I will draw a 3D Model to show you what it will look.

Thank a lot!
 
ti-christ said:
c) I have selected the following LED from Cree: Cool White XP-E P/N: XPEWHT-L1-0000-00F01 (R3 bin) and Royal Blue XP-E P/N: XPEROY-L1-0000-00A01 (15 bin)
Click to expand...

Its not one of your questions, but if you have not ordered already go back and look at page 70 of this thread Starting with post# 1747

Question #3, depends on the cooling capacities of your design ( heat sink ability and active or passive cooling, fans or not)

Question #5 as long as the wiring is sufficient you can remote mount the drivers.
 
ti-christ said:
1 - What do you recommand for LED group dimension of cover 1/3 of the tank?
2 - Is 12"x13" enough?
3 - If I am using 2.5" LED spacing rule, I will need about 18"x20" heatsink to fit all LED of a group. Can the LED be closer?
Click to expand...

12" x 13" over a 21" x 21" opening is probably not enough spacing, especially with optics. I wouldn't get hung up on spacing between LEDs - just pick a heatsink scheme that allows you to get LEDs within about twice the LED spacing of the tank walls. In other words, if you've got 3" between the LEDs, you probably want to start them 6" in from the sides. So on your tank, with a 21" x 21" opening and essentially three 24" x 24" areas to light, you might want 18" square heatsinks. Of course this all goes out the window if you want a non-standard distribution of light over the tank - for instance, if you have a big overflow in the center, you wouldn't want LEDs over it!


4 - Is my FRAEN optics good? Or I should go with the Wide Beam which has a 39 degrees beam angle?
Click to expand...

21 degrees is pretty tight. What height above the water will your LEDs be? Unless they're going to be several feet up, I'd probably go to a wider optic.

5 - Where do you put the LED driver? Do you put as close as possible or you can put it under the tank?
Click to expand...

What sort of driver are you using?

6 - What is the PWM frequency to you use to drive the LED?
Click to expand...

See above. Depends on the driver you're using.
 
I looked into Fraen optics briefly. The only place i found was selling them for like $5 each which was a lot more than i wanted to spend on optics. I tried contacting the manufacturer via email but they ignored me. On the phone they basically told me they wouldn't deal with me.
 
HeneryH said:
Rather expensive for only three watts isn't it?
Click to expand...

It's three channels, 700mA each, up to 48v each. It's basically like the DC stage of three Meanwells put together. Or, six buckpucks put together.

But I'm a bit of a skeptic, since it's vastly cheaper than anything comparable. Hence my comment above about seeing what's inside it. It's interesting that they call it a "repeater" instead of a driver.
 
der_wille_zur_macht said:
It's three channels, 700mA each, up to 48v each. It's basically like the DC stage of three Meanwells put together. Or, six buckpucks put together.

But I'm a bit of a skeptic, since it's vastly cheaper than anything comparable. Hence my comment above about seeing what's inside it. It's interesting that they call it a "repeater" instead of a driver.
Click to expand...

I get the repeater deal. It takes the on off signal from another string of LED's. I could see where it would be useful in a big build. One of those (with a 24v supply) you could make 3 Mean wells run 3 24 LED strings.

The thing I though was interesting was the PWM control. If that means applying the PWM signal is what will turn on the individual channels (which sounds right) one driver could be used to control 3 different strings of LED's at different intervals. I was thinking 12 Blues for dusk/dawn, add in 6 Blues and 6 whites for stage 2 and then 12 white for midday. Just don't know If I am that ambitious:lmao:
 
der_wille_zur_macht said:
12" x 13" over a 21" x 21" opening is probably not enough spacing, especially with optics. I wouldn't get hung up on spacing between LEDs - just pick a heatsink scheme that allows you to get LEDs within about twice the LED spacing of the tank walls. In other words, if you've got 3" between the LEDs, you probably want to start them 6" in from the sides. So on your tank, with a 21" x 21" opening and essentially three 24" x 24" areas to light, you might want 18" square heatsinks. Of course this all goes out the window if you want a non-standard distribution of light over the tank - for instance, if you have a big overflow in the center, you wouldn't want LEDs over it!
Click to expand...

I am not sure if I have understood correctly what you are trying to tell me since english is my second language.

What is the optimal size of the lighting for 24"x24" tank to have a nice coverage over the tank coral?
 
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