LED lighting layout

[NanoReefGuy]

Hi All

 

Rather than hijacking other people's threads on their LED lighting I decided to start my own to document the saga of getting my own LED lighting going.

 

My plan is to retrofit a BC 29 stock canopy with a combination of 30 white, 15 royal blue & 3 UV LEDs. They are a mix of CREE & Rebels. This should make an eyepopping amount of light. Hopefully it will be bright enough to keep a clam, an anemone or SPS corals.

 

I am working on a programmable controller to look after the LEDs. I have a quick & dirty solution that I will be able to put together fairly quickly to start with, but am also thinking of a more elegant solution to follow on. This will have to wait until the hardware is built. All of this will be drive by a single 24V power supply that I have.

 

I am going to use a 1/8 x 17 x 9" aluminium plate with heat sinks on one side and the LEDs on the other. I've drawn this up in Google SketchUp and made pictures:

 

So here is the first question that I am thinking about.

My original LED layout was to make them evenly spaced to avoid having areas where the heat sink is having to dissipate more heat. The question is should I put optics on the outside LEDs to avoid some of the light spilling or should I just move the LEDs all closer together?

 

Any comments?

 

 

Thanks

NRG

[coolwaters]

OMFG!!!

 

hope your going to use a big PC fan with that heatsink...your fins should be a lot longer...

r u going to power each at 1w? cuz with the 3w version your talking about almost 150watts of LEDs.

 

btw how much r u spending on it?

[evilc66]

The biggest porblem you are going to run into with optics is the differences between what you can get for the Rebels and what you can get for the Cree's, degree wise. The only optic available for the Endor Stars is the Luxdrive 25 degree unit. Idealy, you should be looking at a 35-40 degree optic/reflector to get the most spread at a short distance.

 

One option would be to put the white Cree's on the outside and leave it with no optic. The tighter 90 degree viewing angle will help reduce the amount of light that is lost outside of the tank. For this setup though, I wouldn't even worry about it. You are going to be pumping an excessive amount of light into that tank. Remember, it's not about lumens, it's about PAR and you have plenty of that.

 

You are going to be really short on blue though. You need to shoot for close to a 1:1 mix to get a good 14K look. Right now you will barely hit 10K.

[NanoReefGuy]

Hi LED folks

 

CW

Really appreciate your comments.

I am building the controller to be capable of delivering 700mA to each LED. Max power should be approx 2.5W per LED or about 115W from the whole array. This is the max power that I will be needing to cool inside the canopy. There is 110 in^2 of heat sink and a fairly large piece of aluminium. Longer fins would have been better but I am trying to keep all of this inside a stock looking BC29 canopy (and I got a bunch of these heat sinks for free ). I will compensate for the shorter fins with increased air flow from 2 x 80mm computer case fans. . I know that nanotuners make a 144W CF lighting upgrade for the BC29 that uses 2 smaller fans and they report a drop in temperature in the canopy. I am hoping that I will be able to keep the temp in the canopy below 100F.

So far the whole thing has cost ~$600. Its more than I really wanted to spend, but I am really hoping that the results will be worth it!

 

Evil

Thanks for the great suggestions. I will look at what happens ifI put the CREEs at the outside to take advantage of the narrower beam angle. In my original plan I was hoping not to need to use optics on the LEDs at all. Now I am thinking that I may just use optics on the outside LEDs to try and prevent spilling so much light onto the floor. The idea was to run 8 strings of 6 LEDs. Each string having a 3 emitter Rebel star and 3 CREE stars with each in a nice neat line across the heat sink. I could move the Rebels into the center and pair them into strings with 6 emitters. Let me update the drawing to see how this would look.

 

I'll try to post an update today.

 

Cheers

NRG

[NanoReefGuy]

Hi All

 

So I took a look at the overall design and agree that moving the Rebels into the center part of the array would be better given that they have a wider beam angle. The new layout will localize the heat a little more because of the triple LED per star that the Rebels use, but I think this is manageable. This will also keep more light in the aquarium. If necessary I will add optics to the outside row of white LED.

 

The white balance is a bit of a question. 10K is a little lower than I would like. Once this is assembled I could replace individual CREE blue stars with a Rebel blue star getting almost a 3 times increase. I think I will wait and see on this idea.

 

I have also been thinking about the original plan of using a 24V power supply. I have seen power supplies that are adjustable from 24-48V. I may use one of these instead of the straight 24V that I was thinking of originally. If I increase the drive voltage from 24 to 32 then I have the option of adding 2 more LEDs in the future if I want to increase the amount of blue.

 

Cheers

NRG

[Reeferton]

I use AutoCAD to figure the beam spread of my LEDs. If you give me the tank dims, and the height, I can draw it up in cad and you can compare the different degrees. Just send me a PM, won't take me but a minute to do.

[coolwaters]

if your going to use that many whites then your going to get a 10k temp. i have more blues then whites and im getting something like 11-12k...wanted a more purple light...guess i should have gotten 3 whites and 9 blues...

 

u can try to run the whites at 1w if u want a deeper blue. and the rest at 2-3w.

you should probably think about getting one of those 120mm PC fans. pretty cheap too.

 

$600? it shouldnt be that much =/

how much are u getting the LEDs for?

[evilc66]

Are you going to be able to control the brightness of this array? I started thinking earlier today, that if you are putting this in a stock BC29 hood, you stand a good chance of scorching your corals. You are going to be throwing a lot of PAR at that tank. Making it easily adjustable is going to be a must.

 

You might want to think about your plan for adding more blue now rather than later. Because you mixed and matched your LED types, you will find it harder to not make your light output splotchy by changing a few LEDs. Try and figure out where you are going to make the next change and plan for it ahead of time.

[NanoReefGuy]

Hi

 

CW

Yeah its hard to believe that I spent that much just on parts ... My wife reminds me of this regularly. Here's where the money goes:

Qty Description Cost Extended

1 Used BC29 Canopy $20.00 $20.00

8 Buckpuck 3021-D-I-1000 $17.99 $143.92

5 Luxeon Rebel star White 3 x 180lm $26.33 $131.65

3 Luxeon Rebel star Royal Blue 3 x 525mW $28.43 $85.29

15 Cree Q5/R2 stars $6.50 $97.50

9 Cree Blue stars $7.00 $63.00

3 UV Stars $8.19 $24.57

1 Stamp Stack board $79.95 $79.95

2 80mm Computer fans $8.00 $16.00

$661.88

I will probably try to stick with the 80mm fans because they will mount into the canopy without needing to hack and slash. If they really aren't up to the job I'll look at 120 and cutting bigger vents in.

 

Evil

I haven't said too much about the controls yet, but yes the LEDs and the fans will be controlled by a microcontroller. I should be able to adjust each LED string in 1% brightness steps and turn on/off at programmed time of day. The plan is also to include temperature sensing of the heat sink and the water to decide how fast to be running the fans. Also if the water temp starts to parbroil things it will reduce or shut off the LEDs. Hopefully this will allow for cool & quiet!

 

Agreed that I should be planning ahead (The 7 P motto). Having said that it should be easy to replace single blue emitters with triple Royal Blue ones to get the color temperature to move up if needed...

 

Cheers

NRG

[DarkDevil]

I have stated in my LED thread, I am sure nobody reads it... is that don't use buckpuck if you are going to use a LOT of them, and 8 of them definitely seems a LOT.

 

Also, maybe I missed it in earlier posts, but why are you mixing rebel and cree? the price seems a bit high, coz I bought my cree XR-E for < $5 each.

 

last, optics does help, I would ditch the buckpuck and use the money towards optics.

[NanoReefGuy]

Hi DD

 

Thanks for adding to the thread. Your comments on using the LM3401/3404 are bang on. I will probably do a custom board later and use the 3404. I just wanted a simple way to try all of this out early on. I am more of an AVR guy so I am building controls based on the ATTiny44. It just may take a while for me to actually get it running.

 

I just read your thread. I should have read it sooner . You have some great information in there.

 

How did you do with your heat sink in the end? If you are still looking for a thermal conductive materials to use between the layers I would recommend Thermagon. We use it at work for high speed stepper drivers and it works great.

http://www.lairdtech.com/pages/products/Th...w.thermagon.com

 

My heatsink is a 1/8" aluminium sheet with finned sinks on the back. I am planning to drill & tap to get good contact between all the layers.

 

Glad that there are lots of people working on this for aquariums. We all should benefit from learning together. Evil & CoolWaters have done a great job in paving the way for us Thanks Guys!

 

 

Cheers

NRG

[evilc66]

Awe shucks. You guys are just sayin' that

[NanoReefGuy]

No Really ....

 

:bowdown: :bowdown:

:bowdown: :bowdown:

 

 

However if I get this to work I want to be elevated to demi-gawd status

 

BTW

I was working on my heatsink tonight. The bare aluminium weighs in at 5 lbs! If mass is a heat sink is good I think this may work!

 

 

Cheers

NRG

[evilc66]

Mass is great for stability. I think the 6"x6" heatsink I'm using is about 3lbs.

[snatchbak]

Why dont you use a line volt power driver like Xitanium...

Also, IMO you should not mix the different LEDs

[NanoReefGuy]

Hi Snatchbak

 

I have been holding out to keep only low voltage above the saltwater. I have never liked the idea of 120V power running close to saltwater . This system will be driven of 24 or 32V DC. I have a few power supplies are suitable in this range so cost to me is 0$.

 

And before someone else says it I know the risk is the current not the voltage, but higher voltage usually can drive more current through a resistor (In this case me).

 

Why are you be concerned about mixing different brands of LEDs? Electrically I can keep each circuit to a single brand of LED if required, but I don't see the reason for doing this. By mixing LED types I can take advantage of the different beam angles that the companies make. Am I missing something?

 

Thanks

NRG

[evilc66]

You aren't missing anything. There is no dissadvantage electrically to what you are doing, providing your drivers are able to handle the max voltage of the entire string.

 

I don't see any advantage of running a Xitanium driver over a Buckpuck. Lower voltage DC in moist/wet conditions is generally considered safer than running 120VAC. Plus, by the time you get into the higher wattage version with dimming control, you are spending a ton of money ($85 for a 24W dimmable, which has lower output voltage than the Buckpucks) just to elliminate a power supply. Doesn't seem worth it to me.

[NanoReefGuy]

OK

 

Today's another day and I have another change in the plans.

 

In order to get a higher color temperature I have added more blue LEDs and removed some white and 1 UV to allow for the increase. At the same time I am going to move to a 32V power supply. This allows me to use 6 Buckpucks instead of 8 by increasing to 8 LEDs in series per string.

 

Here is the new layout

 

Do you think this will get into the 12-14K range?

 

 

Thanks

NRG

[evilc66]

Should be close. Push comes to shove, you could always back down the whites slightly to get the effect you need. You may have to do it anyways with the amount of light you are throwing around.

 

Have you figured how high off the water you are putting the array?

[NanoReefGuy]

Hi Evil:

 

Well I am retro-fitting it into a spare BC29 canopy, so the array will be about 1.5" off the water. It will be enclosed in the clear plastic shield that is in the stock canopy to help keep moisture from being a problem and to force the air flow through the heat sink.

 

Just working on layout of the aluminium so that I can drill a bunch of holes & then go crazy with the taps. I seem to recall that you did this instead of using thermal epoxy. Do you happen to recall what thread size fits well? It looks to be around 6-32 or 4-40.

 

 

Cheers

NRG

[DarkDevil]

I have been busy these couple days, that's why I didn't even update my progress. I did finish making my circuit board and the fans I ordered just came yesterday, so I will be updating my thread soon. anyways, I will end up drilling, tapping and use screw to hold them together, I will see what I kind of taps and screws I can find in home depot later.

 

my advice is, get the biggest heat sink you can find if space is permitted, these things does get hot and get hot fast, and the LEDs will run better and longer if you can provide enough cooling. dont' forget the buckpuck gets a bit warm also.

 

if you are going to use PIC to control the buckpuck, don't worry about color temp range what your LEDs will give you, since you can ultimately bright or dim them using the PIC. all you need is plan ahead on which buckpuck is controlling which LEDs. good luck, it's a fun project nonetheless

[evilc66]

The stars are sized for a #4 screw, so a 4-40 or 3mm tap will work fine. I used 3mm, but I seem to prefer metric over standard. It's personal choice on size. Use a bigger screw to attach the plate to the heatsinks. It will be easier to put more clamping pressure without stripping the threads or the head.

[NanoReefGuy]

Thx

 

Work stocks both M3, M2.5 & #4, so I should be set. I tend to prefer metric also. I was planning to drill the hole through the aluminium plate slightly over sized so that they will pull the sink, the plate and the LED tightly together. Ditto for the bigger screws to keep the pressure on the heatsink.

One thought to increase the force drawing the pieces together using UNF threads. More threads = more shear strength!

 

When its all done I will use some Arctic Silver to maximize the heat transfer.

 

I have also been thinking about polishing the face of the aluminium to try and cut down on losses where light bounces of the water surface (Total internal reflection)

 

Now I need to get busy with a drill press and a tap

 

 

Cheers

NRG

[evilc66]

I would polish the aluminum for another reason; Thermal transfer. If you take out the irregularities in the surface, the thermal compound will work better, and you will need less of it. The thermal compound is there to displace the air in the voids between the two parts with something more thermally conductive. Lap both surfaces up to about 600 grit, then polish. It wont get much better than that. I have been polishing the heatsinks I have been building for others for that reason.

[Reeferton]

I'm a jeweler on the side (make more money doing CAD as a day job). Although I haven't polished aluminum, I have polished palladium, platinum, gold (all alloys), silver, nickel, brass, copper, and bronze... So I'm sure I can offer some pointers if you go in that direction.

 

Honestly, I don't know how much of a difference mat aluminum vs. polished would have on heat transfer, since this is all on a very molecular basis. The silver in the compound does a lot though, as only diamond is more heat conductive than silver.

 

Also, was it the Solara I saw that had 10k LEDs? I saw the Cree X-REs listed as 5k-10k, does that mean theres a bin of 10k white LEDs out there?