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Chad

Chad's LED fixture

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I had planned on waiting until I had a complete and working LED fixture to make my build thread... But I have started talking about it more and figured that I would start my build thread to bring everyone up to speed with and add a little motivation for me to finish the project. Also, I have been recently second guessing a few decisions, so a little validation of my thinking would be nice.

 

Before I begin, I would currently consider my project to be 75% complete. I have all the parts except for a last-minute change on which LEDs I would use and some fasteners. The fixture design is complete and essentially waiting on me to submit the design to be CNC cut. My programs are written and working and just need final in-place tweaking.

 

To start, here are a couple of CAD renderings of what my fixture will look like:

 

gallery_7179_150_15514.jpg

 

gallery_7179_150_4993.jpg

 

Basics:

LEDs - 66 LEDs driven by 11 individually PWM controlled DIY drivers based on a CAT4101 constant current chip (courtesy of Rob). The LEDs are approximately centered on a 2.1" x 2.4" grid and have 90* optics more for fixture cleanliness and the final look than anything else. I expect I will hang the fixture 8-12" off the water.

The PWMs are driven by an arduino mega microcontroller.

System status is outputted to a 128x64 blue GLCD display.

Various behavior characteristics are inputted via a button and menu system.

 

Here is a picture of my planned layout and color breakdown:

 

gallery_2632346_867_11198.jpg

 

Based on some Chad-generated funny math, I think the final color temperature mix will be around 12k (at least that is my desire).

 

The channel arrangment is loosely based on columns putting like colors on a single channel (with the exception of the center channel, which is mixed) and a separate channel for both blue and warm white... I will be able to separately control those so they will not overpower anything.

 

A post by Jon Lazar a while back inspired me to think of different ways to use LEDs (yes, Jon, I am blaming this whole project on you!!). My goal is to be able to cast shadows one direction in the morning and another direction in the evening... at this point (if you are still reading ; ) you are probably asking how are you going to do that?

 

My answer? By programming the lighting distribution into a Gaussian curve and then "moving" it over the course of the day - basically the fixture would simulate where the brightest point is coming from and vary that over the course of the day. So, what does that mean and how would you do that?

 

My fixture has 11 LED channels, so I programmed a Gaussian curve to have 33 channels. Basically this means that the curve can move completely "off screen" to the left or right. Here are some graphical images to explain (the top is the full 33 channel Guassian, the bottom is the 11 active LED channels), when looking at these, notice that I normalized the Guassian peak to 0.75 (to represent maximum current) on the y axis, so 0.75 means 100% intensity on that particular channel.

 

This is with the peak located at channel 0 (notice on the bottom graph that intensity is just starting to rise):

 

gallery_2632346_867_15073.jpg

 

And channel 11 (the first active LED channel):

 

gallery_2632346_867_12388.jpg

 

The peak on the center channel (high noon):

 

gallery_2632346_867_41385.jpg

 

Channel 21, the last active LED channel:

 

gallery_2632346_867_18861.jpg

 

And finally channel 32 (the last channel):

 

gallery_2632346_867_29160.jpg

 

I also have programs for cloud and storm simulation. Basically, the controller chooses semi-randomly how cloudy a given day will be and then plans how long clouds will be and how much intensity will be reduced by the cloud. If the cloud reduction intensity is greater than a certain amount, there is a probability that a storm will occur within that cloud.

 

That is the plan. It should be complete within a week or two of getting my parts back from the CNC machine and I should find our more about that soon.

 

Thoughts, comments, ideas?

 

(thanks for reading!)

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What are the total dimensions of the fixture, and what size tank is it going over?

 

Also, you may want to consider leaving the optics off certain led's like the warm whites. This will ensure there is no spottinglighting.

Edited by BowieReefer84

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This will go over my 60 gallon tank, the fixture is 36x18x5.5.

 

I took PAR readings with my current light fixture and I plan to adjust the intensity of the lighting to match (or close to it) approximate my previous PAR levels.

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Chad,

 

I'm speechless. That sounds awesome! May have missed it but what bulbs are you going with? The CAD renderings are really nice. My biggest concern with DIY fixtures is the aesthetics of the fixture itself but it looks like you've really nailed that!

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Thanks, Roni. That is my biggest concern too. I wanted this to look sleek and modern - something that I wouldn't mind hanging in my living room. The grey in the fixture is polished perforated steel. The bulbs are all CREE XP-somethings smile.gif The grid shows the breakdown of the colors.

 

Mike, if you look closely at the perforated steel in the top rendering, the left third has sort of a lighter color on a portion of it. This is one of the two outputs for the fans, there is another one on the opposite side in the same spot (I decided to make the decorative trim functional). There are two 92mm 30 CFM fans that draw air from beind the fixture and blow it across the heat sinks inside the fixture. Also, there are 11 separate heat sinks (a la Rob) with 6 LEDs mounted on each one.

 

As this progresses, I will provide renderings and take pictures of everything (I want to see how close my finished product is to my computer product smile.gif ). Hopefully this build thread will only be open for a few weeks.

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What kind of heatsink are you using for those dimensions? Also, I noticed in the last CAD drawing that the LEDs seem offset to one side, is that for the electronics? Please post a full parts list with sources when you are done. It will make is much easier for me to duplicate! :biggrin:

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I am using some heat sink material that Rob made for me from parts out of the recycling bin. It is ~1.5 x 15"

 

Yes, the LEDs are offset toward the front of the fixture by 3 inches. This gives me space to put the power supplies, fans and electronics in the back and have all the stuff hidden (without making the fixture any thicker).

 

LOL, I have a parts list now (albeit not consolidated, it is mostly at the subassembly level or by order). I will post it when I have time to consolidate it. I have also been keepling lessons learned for someone following my footsteps that I will post in my conclusion to the build. More to come!

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Also, you may want to consider leaving the optics off certain led's like the warm whites. This will ensure there is no spottinglighting.

 

Sorry, I missed this. I may if I have to, but I think one of the problems with many DIY fixtures is exposed electronics in a warm, humid, and salty environment will certainly yield a shorter than intended life. If I have issues I will either raise the fixture (will hang from ceiling) or lower intensity on that channel. Hopefully I won't have to remove the optics (which are pretty wide angle anyhow).

 

Once it is complete and opperational you should post a link on RC. Title it something like "BEST diy led fixture ever," and watch the comments flood in lol

 

LOL, that would be awesome, I will have to do that!

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Here is a parts and source list:

 

Sub-component...Part............................Source

Controller......Arduino Mega 2560...............http://www.sparkfun.com/products/9949

................Arduino protoshield.............http://www.sparkfun.com/products/9346

................Real time clock.................http://www.sparkfun.com/products/99

................GLCD............................http://www.sparkfun.com/products/9351

................12 Vdc 25W p/s..................http://www.trcelectr.../rs-25-12.shtml

................10k Ohm resistors...............Radio Shack

................0-10k Ohm Pot...................Radio Shack

................Wire Misc.......................bulkwire.com

................4 buttons.......................Radio Shack

 

Drivers.........Boards and misc driver parts....FishMan

................24 Vdc 200W p/s.................http://www.trcelectr...sp-200-24.shtml

 

LEDs............27 royal blues..................RapidLED

.................6 blues........................RapidLED

.................9 cool whites..................http://www.rapidled....-R5-Cool/Detail

................18 neutral whites...............http://www.rapidled....al-White/Detail

.................6 warm whites..................RapidLED

................80*optics.......................http://www.rapidled....XP-dsh-G/Detail

................Thermal pads....................http://www.rapidled....d-%28set/Detail

................Heat sinks......................Fishman

 

 

Fixture.........1 4x8 sheet 1/4" black acrylic..AVAST

................CNC work........................AVAST

................Switch..........................Radio Shack

................USB panel mount cable...........http://www.cablestog...=1531&sku=28070

................Misc. hardware..................Mcmaster Carr

................Decorative trim.................http://www.onlinemetals.com/merchant.cfm?pid=13530&step=4&id=1002&top_cat=0

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More renderings. This is the fixture without the top or bottom piece, a look at the inner setup. The top will be removable in practice and is held in by four attachment points in the corners and a shoulder on the eye bolts. The bottom will not be removable and will be acrylic-welded in place.

 

Many of the internal parts are not fully modeled... I just modeled them enough to have prototypical parts that I would need to interface with.

 

gallery_7179_150_16993.jpg

 

gallery_7179_150_29950.jpg

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Thanks! I did the solid models and drawings in autocad and used inventor for the renderings (inventor is an additional model within acad that lets you do cool things) smile.gif

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This is going to look great, Chad. Nice to see you're paying as much attention to the exterior as the interior--by the looks of it, this will rival many of the expensive LED fixtures both in performance and appearance.

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Sweet Chad, I don't really work much with AutoCAD but I absolutely love Inventor (my version is a standalone program...probably same thing?). Gotta love free downloads for students at schools with Autodesk subscriptions clap.gif

 

When do you plan to start, finish and most importantly post pics??

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LOL, I think it might be the same thing (and I agree on the free downloads, that is awesome!!).

 

I used my alma mater to get a low-cost educational copy. It works great, just prints "for education only" on all my drawings :)

 

Right now I am doing a final review of my solid models and drawings to verify that I have everything set up correctly before making my .dxf files. Should only take a little more time of running my alignment and tolerance calcs. Once that is complete, I will send everything off to be machined and I will be rolling. I hope to have my drawings and .dxf files done by the end of the weekend. So maybe late next week? That might be a little optimistic, though.

 

Once I have my fixture parts, this will fly fast and furious, though.

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Garage hack. :laugh:

 

I'm kidding, Chad. Kudos for an awesome job you've done thinking this through. I can't wait to see it at 100%.

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LOL, Tom, and proudly so!!! I cannot wait to have it done either.

 

Perhaps it will be, have a spectrum analyzer handy? We could place a wager on that...

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I submitted my drawings to be turned into reality!!

 

I am really getting excited about this cool.gif

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Some progress today...

 

We cut the prototype fixture out of plywood to test settings and verify fit up prior to cutting acrylic. Good news! Everything went well, plastic to come!!

 

Here are a couple of pictures of the cutting, should have the fixture completed within a couple of weeks... then things should progress much faster to the finish.

 

gallery_2632346_867_21478.jpg

 

gallery_2632346_867_40709.jpg

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Teaser assembly pic:

 

gallery_2632346_867_11033.jpg

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