LED Unit Blueprint

[sweevo]

After reading all the recent posts on the various LED unit's that people have been making I've been inspired to try and make my own !

 

At the moment i'm just at the design stage but would appreciate any comments and/or input that any of you have on my initial ideas etc. Evilc66 come on down !

 

My tank is a 24" cube and currently lit with a 96W T5 unit which i'm hoping my creation will supercede ! After looking at the Aquaillumination unit and some of the reviews etc I decided that i'd use the same CREE XRE LED's in my own unit.

 

With heat generated and cooling being one of the important aspects that need considering with driving LED's I've been considering running these LED's well under the max current ratings, ie @ 350mA, to try and keep the heat generated at a minimum. I was also intending to use suitable Buck Puck's to limit the current. Heat sink wise I was thinking of using one or two large sinks with the stars firmly fastened to it using screws with possibly some form of fan cooling.

 

First up, with regards to the Buck Pucks, I wasn't sure whether running a 700mA unit with two parallel chain's of 8 LED's in series to halve the current per chain to 350mA would have any drawbacks? I'm thinking of using around 32 LED's so part of the thinking behind this is to help reduce costs by halving the number of buck pucks required.

 

With regards to DC power, I was thnking along the lines of a 32V DC supply rated around 2A.

 

So with all the above in mind here's how I "think" I can hook this lot up

 

Two 6-32V DC 700mA Buck Pucks in parallel connected to the 32V DC supply

 

Each 700mA Buck Puck is connected to two chains of 8 x XRE's which are in parallel. Vf for the XRE's @ 350mA (supplied current of buckpuck halved due to two // chains of LED's) is listed as 3.3V.

 

So........

 

8 x Vf 3.3V = 26.4V @ 350mA per chain

 

2 chains in parallel per 700mA buck puck

 

Add 2V to the 26.4V for each Buck Puck = 28.4V @ 700ma (leaving 3.6V unused. Is this too much?)

 

2 Buck Pucks hooked up to the PSU in paralell requires 28.4V @ 1500mA (1.5A)

 

 

What do you think?

Edited October 29, 2008 by sweevo

[NanoReefGuy]

Hi Sweevo

 

Sounds good!

 

If you are trying to avoid the heat by keeping the current low it will work, but you need more LEDs which leads to more heat... sorry if I am stating the obvious.

 

I am building on a largish heatsink doing something very similar to what you propose. Check out my post Lighting Layout. I am trying to squeeze this into a BC29 hood and keep it looking stock on top.

 

The real key seems to be getting a big enough heat sink and the air flow through the heat sink fins to get rid of the heat.

 

Good Luck

 

 

NRG

[evilc66]

Damn sweevo, someone has been doing their homework! Good job.

 

Like NRG stated, limiting your current will only require more LEDs, which leads to more heat. Granted, it will be less heat than running less LEDs at full current, but with an adequate heatsink it shouldn't be a problem.

 

A 24" cube you say? You could take the number of LEDs down to about 18, but run them closer to the full rating, if not full tilt. One of the nice things about the Buckpucks is the option to be able to dim them. If you don't want full power for whatever reason, be it brightness, energy savings or heat, just turn it down. At least you know you have more available if it's needed.

 

Lets just say for arguments sake you go with 18 LEDs (9 Q5 white, 9 XR-E blue/royal blue). You can run all 9 of each color on a single puck, running off 36v power supply dialed down to 32v. Saved you money on the reduction in LEDs, but increased your lumen output by 50%. That may have also increased you wattage by 50% also, but that can be dealt with.

 

What had you planned on for a heatsink? Something from these guys would fit the bill if you haven't picked something out already.

 

Optics are going to be needed for this setup if you haven't realized that yet. Try and get something with as wide a spread as you can. It will help with reducing the spotlighting that can occur, and also get more light deeper into the tank. Something around 40 degrees should work out nicely.

 

You might want to look at going to Cutter Electronic in Australia for some of the parts. They seem to be the only place to reliably get XR-E blues and royal blues. They also have a great selection of optics too.

 

So what do we have now, 5 or so current LED projects? What have we started here?

 

Keep us posted.

[Zombo]

It's a cult. Where's the F@c|<iN6 banner, evilc66?\

 

CHOP CHOP!

[sweevo]

Hi Sweevo

 

Sounds good!

 

If you are trying to avoid the heat by keeping the current low it will work, but you need more LEDs which leads to more heat... sorry if I am stating the obvious.

 

I am building on a largish heatsink doing something very similar to what you propose. Check out my post Lighting Layout. I am trying to squeeze this into a BC29 hood and keep it looking stock on top.

 

The real key seems to be getting a big enough heat sink and the air flow through the heat sink fins to get rid of the heat.

 

Good Luck

 

 

NRG

 

Thanks for the input NRG. Your's was one of the designs that I paid close attention to when thinking about how to make my own. The heatsink/cooling aspect is the part of the project which I think might cause me most trouble. I really want to avoid excess fan noise just so I can keep the LED's running at a safe working temperature (<85C I believe).

 

Damn sweevo, someone has been doing their homework! Good job.

 

Like NRG stated, limiting your current will only require more LEDs, which leads to more heat. Granted, it will be less heat than running less LEDs at full current, but with an adequate heatsink it shouldn't be a problem.

 

A 24" cube you say? You could take the number of LEDs down to about 18, but run them closer to the full rating, if not full tilt. One of the nice things about the Buckpucks is the option to be able to dim them. If you don't want full power for whatever reason, be it brightness, energy savings or heat, just turn it down. At least you know you have more available if it's needed.

 

Lets just say for arguments sake you go with 18 LEDs (9 Q5 white, 9 XR-E blue/royal blue). You can run all 9 of each color on a single puck, running off 36v power supply dialed down to 32v. Saved you money on the reduction in LEDs, but increased your lumen output by 50%. That may have also increased you wattage by 50% also, but that can be dealt with.

 

What had you planned on for a heatsink? Something from these guys would fit the bill if you haven't picked something out already.

 

Optics are going to be needed for this setup if you haven't realized that yet. Try and get something with as wide a spread as you can. It will help with reducing the spotlighting that can occur, and also get more light deeper into the tank. Something around 40 degrees should work out nicely.

 

You might want to look at going to Cutter Electronic in Australia for some of the parts. They seem to be the only place to reliably get XR-E blues and royal blues. They also have a great selection of optics too.

 

So what do we have now, 5 or so current LED projects? What have we started here?

 

Keep us posted.

 

Hi evilc66, thanks for taking a look. With regards to dimming i'm seriously thinking of using a PIC like DarkDevil and ramp up the brightness over a couple of hours and dim it likewise at the end of the light cycle. Will need to get all the Arduino stuff and get up to speed for this though.

 

Also, using buck Pucks with current to spare makes a lot of sense now you mention it. A lot easier to increase the o/p than remove and replace one with a higher rated one isn't it?

 

Heatsink wise, the site you mentioned was the supplier I was considering using. Can't remember whether I found these guys from your own build thread or someone else on here but they seem to fit the bill.

 

Optics is something that i'd not really considered but I'll take a closer look at them at Cutter, as what you're saying makes perfect sense.

 

First up I think i'll probably knock up a simple prototype, just a few LED's on a buck puck, mounted on a heat sink controlled by the PIC. If that all goes to plan i'll then i'll look at buying the rest of the kit for the full unit.

 

 

Thanks for the help guys.

Edited October 29, 2008 by sweevo

[evilc66]

If you are looking to dive into running this off a micro, maybe you would also consider building your own drivers. I have been playing around with a new driver based on the reference design for the ST Micro STCS1, and just successfully got it to dim and brighten using an Arduino. Super easy to do. The STCS1 design lets you run things up to 40v so you can get a few more LEDs on it. It will also handle up to 1.5A if you need it to.

 

Optics will be important for a 24" deep tank, unless you want to keep the bottom half really low light. Bare emmiters will perform well up to about 12". After that, the lux and PAR levels drop significantly. Using an optic will bring the levels back up to a reasonable level. Not sps on the sandbed levels, but more than enough for softies and lps.

[Splumph]

If you're concerned about noise, I have a low flow 120mm fan over my 12" array (used the big heatsink from heatsinkUSA), and it's so quiet you can't even tell its on. (it was actually off for I estimate 4-5 hours yesterday, and I didnt notice until I looked at it, the heatsink was just a little warm. My array has 12 LEDs at the moment, so if yours is 24" (not sure if you want to go the whole length of the tank or not) using 18 LEDs, two 120mm fans should be more than enough. I don't think I'm anywhere near my heat dissipation capacity due to the mass of the heatsink.

 

I'm glad to see the DIY LED thing catching on too, it's hard to describe in pictures how these things look in person.

[evilc66]

You gotta love those heatsinks for the mass. Big buggers!

 

The 6"x6" heatsink I got from them can run the 64W array without a fan. It gets fairly warm, but not enought for me to worry about damage to the LEDs. Normally I have an 80mm Panaflow fan blowing across it. The 36"x8.5" version is what I want to run over my 40B. 15.5lbs!

[sweevo]

Slowly getting there now with parts for the prototype now.

 

Ordered 12 cool white XRE's (Q5 WC ) from DX, also picked up a couple of decent heatsinks nice and cheap off ebay.

 

Got a nice benchtop PSU and Arduino board to unwrap on christmas day too.

 

I've been looking at Royal Blue LED's tonight and i'm a bit confused about all the different Luxeon models that are available. Certainly seems harder to get hold of Royal Blues in general

 

The Rebel's look good value (525mW @ 700mA, approx $4.50) especially when compared to the XRE's which seem to go for a few dollars more each. Is it worth paying another $30 for 12 XRE's as opposed to 12 Rebels?

[evilc66]

The XR-E royals are quite a bit more powerful than the Rebels. They have a little better color to them also. Thats what I'm using on the fixture I built. They look great.

 

You'll like the Arduino. Easy to get into, and lots of online help to get things moving.

[sweevo]

Ok, Evilc66, on your recommendation XRE's it is

 

The Arduino stuff i've seen on the web is great. I'm pretty much decided that if it's as easy to do as it looks i'll probably end up with heat sensors and an LCD display !

Edited November 27, 2008 by sweevo

[evilc66]

It's been quite a while since I did any programming, and never for a micro, and I picked it up pretty quick. If you want a cool LCD, go to Fun Gizmos. They have a 2x16 character display that will take serial (easiest), I2C, or SPI (you'll learn about those soon enough)., and only $25.

 

I have the display working, reading and writing to a real time clock, output to my new LED drivers, and reading and writing to the onboard memory. Just need to put it all together to make a useful program now.

[sweevo]

Sounds like your next model is going to raise the bar AGAIN

 

Just ordered my XRE Royal Blue's from Cutter. I also bought some optics while I was there. Ended up going with 40 & 60 degree optics, 12 of each. I'm planning on using the 40's for the deeper areas of the tank like you originally suggested and maybe use some or all of the 60's for the shallower areas.

[evilc66]

Sounds cool.

 

I don't know if I'm going to integrate the controller into any fixtures I build for people just yet, but it will be going into my own 36" beast (240W of LEDS )

[sweevo]

Sounds to me like you're making an LED Sunbed to top up your tan !

[evilc66]

I'm half Irish, half English. I think a sunbed would be a poor investment on my part

[sweevo]

The Royal Blue's and the optics arrived this morning from Cutter.

 

The stars don't have much spacing between the +ve and -ve contacts and the screw holes. Did you guys use acrylic washers or something to prevent the screws from shorting the supply to the heatsink?

 

Oh before I forget, hope you all have a Happy Christmas.

[evilc66]

That can help if the screw heads are too big. Flat head screws can work also, but they tend to damage the star. You should be able to find nylon or phenolic washers at most hardware stores, and sometimes Radioshack.

 

Merry Xmas to you (and everyone else)

[not_sponsored]

I'm a little confused with cutter's website, what exactly did you select to get the royal blue and white leds?

[sweevo]

I'm a little confused with cutter's website, what exactly did you select to get the royal blue and white leds?

 

Just sent you a PM with some help. If you don't know about LED Bins then take a look at the LED Binning & Labeling PDF available on the same page. Might also be worth you looking at the datasheet too.

 

HTH.

[sweevo]

Guys, will the pins on a buckpuck plug directly into a breadboard ? Looking at DarkDevils own thread it does look like he's plugged them directly into a breadboard but thought i'd check. Was thinking of ordering them without the wire harness if they do. Thanks.

Edited December 30, 2008 by sweevo

[evilc66]

They have standard 0.1" spacing thats the same for breadboards and protoboards.

[sweevo]

Glad I read your recent post on PAR readings with 40 degree optics this week Evilc. I was considering getting a few 25 degree ones for the deeper areas of my tank !

 

I've now decided to go for 30 LED's ( already got 12 x Q5 XRE whites and 12 x XRE Royal Blues ) so I need to buy another six LED's. The plan is to drive five rows of 6 x LED's (26V PSU) but i'm wondering whether I should add a couple of UV's in there? Would two 3W UV LED's be over the top? My tank's a 24" cube. I was thinking of using them without optics, especially after seeing those PAR readings !

 

My buckpuck order has had to be cancelled due to a 4 week wait from a UK supplier so i'm gonna see if ordering them with these new LED's from elsewhere will save me any money. With DX and KD's free shipping it probably won't but bargain hunting is part of the fun isn't it?

 

Got my screws and nylon washers now. Need to pick up some cable and solder this weekend then I can make a start (AT LAST) while I wait for the buckpucks.

Edited January 9, 2009 by sweevo

[evilc66]

2 UVs won't be overkill. 4 would even be fine on that size tank. I wouldn't go any more than that though. You might want to throw on some wide angle optics to get it deeper if you plan on sps in the bottom of the tank.

[sweevo]

I'm gonna have a think about the UV's while I start work on my prototype.

 

Nothing too flashy to begin with just 6 x Royal Blue XRE's and 6 x Cool White (WD) Q5's driven by buckpucks and controlled by a simple PIC/Microcontroller program that increases and then decreases the power to the whites and blues independently over a period of time.

 

So here's the first few pics.

 

My Cree XRE Cool Whites (WD Q5's), Royal Blues and optics .

 

 

The first I ordered were the whites and I didn't realise how important the size of the PCB might be. The Q5 WD's were only available on 16mm discs from DX, all the star mounts were lower bins and/or warmer temperatures which is why I opted for these. I should be able to manage but it's not going make life easy, especially as there's limited space after applying the optics.

 

Heatsinks picked up second hand off ebay. I plan to use a 12" x 12" on the actual unit I intend to use but thought since they were nice and cheap they be ideal for playing around with etc.

 

 

Here's the different LED types fastened to the heatsink with brass screws and nylon washers to avoid shorting the terminals to the heatsink. You can see how tight space is on the 16mm discs from these.

 

 

 

And finally here's each LED fastened and with their optics in place.

 

 

 

I've got my wire and solder so hopefully i'll get the stuff all wired up this week.

 

Then comes programming the arduino and connecting up the buckpucks when they arrive.

Edited January 11, 2009 by sweevo