High-tech canopy controller for 100 gal: build journal - The Planted Tank Forum
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post #1 of 3 (permalink) Old 02-15-2014, 06:00 AM Thread Starter
Algae Grower
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High-tech canopy controller for 100 gal: build journal

During the next few months, I will be building a (grossly overpowered) sensor monitoring overhead aquarium controller with lighting based on Arduino using:

1. 240W of cree XML2 cool white LED's running on 8 seperate pwm dimmable drivers in order to run cool lighting effects across the tank, like a passing cloud or moon, or a variable intensity nighttime fish cool white rave party.
2. a servo to control CO2 according to the level in the tank
3. an auto-fertilization system,
4. a sensor array with temperature, dissolved O2 and and pH sensors, pre-built
4.5 a self-built co2 sensor using a colorimeter which reads the color of drop checker indicator solution
5. a raspberry pi ethernet front end with a host program on the local network to send task scheduling information to the system and to display graphs from the sensors for close micromanagey monitoring.

At the time of posting, Phase 1, lighting and device enclosure has been underway for a month. After the China-wide bender that was their new year, they finally started shipping electronics parts again on Monday. once I got the parts ordered I decided I would post this thread so nobody else would start ordering the wicked sick 3a drivers I found for 7 bucks a pop.

I have never built an LED fixture. The research I did was aimed at cost reduction with as much power as possible. Essentially,

I am going to mount these (though I found them for cheaper): http://www.ledsupply.com/leds/cree-x...high-power-led

on a couple of something like these: http://www.satisled.com/power-led-al...60cm_p891.html

and run a group of four leds with some of these drivers, which are super nice for what I'm doing: http://www.prodctodc.com/dc-4530v-to...l#.Uv8MR_ldUxi

The entire thing will be mounted in a 52x4x12" rifle case with the foam inserts taken out, it was the cheapest plastic enclosure for this application I could find. http://www.cheaperthandirt.com/product/8-PLANO-153101

I will post an update when the parts arrive and I have started playing with these fancy LED's.
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post #2 of 3 (permalink) Old 04-07-2014, 08:13 AM Thread Starter
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It's been a while since I started this. The light is complete, and has been over the victim tank for a month now. I have installed 18 (six strings of three) CREE XML-2 cool-white leds on star pcbs, a 24v power supply, six of those rad drivers, four 22" reflective heatsinks, an Arduino Mega 2560, and a sweet little raspberry pi.

note: my building techniques are sometimes somewhat reckless, estimative, coffee-fueled, and inadvisable

The first thing I did was modify the rifle case and attatch the heatsinks. Popping out the inserts was easy. I cut holes in the exterior with a soldering gun. I drilled holes in the aluminum heatsink and lined them up with holes I was drilling in the case and bolted them on. The case at 55" was not quite long enough for my tank, so two small sections of a 2x4 were bolted on as well to compensate. The case buckles, slightly, when sitting atop the tank on these beams, but thankfully my tank has a narrow metal strip dividing the top metal part that the middle between the heatsinks rests nicely on. Further reinforcement will be necessary if I move out and get a tank of my own and build another one of these.

Next I attatched the PSU and drivers. Dumb, because I needed to solder pwm inputs to them all and removed them later. I attatched them with machine screws to the lower lip of the casing. The PSU hangs off the top of the case to balance the weight of the heatsinks and allow the case to stand upright (IT LOOKS SICK.) I wired up one of the drivers to the psu using high gauge wire and examined its properties using a potentiometer. Don't follow the wiring in my pictures. You might die.

The drivers are wonderful. They have two adjustable screws, one for constant current, and one for constant voltage. This means that the output current AND voltage of the drivers can be manipulated, from 0.1-5a and from 0.8-30Vdc. Extremely versatile for led applications. The drivers are also dimmable with PWM. (The Arduino requires a simple PWM frequency prescale change to interact with the input on the driver). I hooked up the rest and tuned them to output a voltage and current equal to just under the max rating for the leds times three, and attatched them to strings of three leds in series. It's bright...

I had never seen the ceiling in my co-op's common room such a vivid purple. These LED's are some of the shiniest things I have ever seen. I used thermal adhesive pads made specifically for star pcbs to attatch them to the heatsinks, which works wonders. I also used heatsink glue, a bit more troublesome, and I even tried a mixture of normal cpu heatsink paste and superglue, which worked for the most part as some of the first ones I installed are still working, others burned out. Don't try that unless you want to risk burnt leds, which turn ugly and yellow.

I ran the lights at full power with an aquarium timer for a while. The plants exploded. In a week my hm had started carpeting like it meant business. Then I got started on the programming. Learning to program the Arduino made me learn to hate C. And it also made me hate how slow the Arduino is for certain things. I decided to use my Arduino as a sort of slave to my pi, and in the process I decided I liked python far better than C. I am using a python library called firmata which just tells the Arduino what to do and when. Python does the rest. In conjunction with a library called APScheduler, I wrote functions to direct the Arduino to dim the lights on and off over a period of time. The program runs quite well, it's all modular and stuff. It has been controlling my tank for the past three weeks without issues or burnouts.

I am currently working with my dad on getting the internet front-end online and fully working. So far I am able to access a web page which can set the brightness of the lights, start the dimming cycle on or off, and do an instant startup and shutdown. More on this in the next post.

Pictures will come after I sleep.
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post #3 of 3 (permalink) Old 04-07-2014, 12:42 PM
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Very jealous. Sounds amazing! I look to do something similar, so I'm interested to see how it all goes for you :-) sounds mostly finished though so congrats!
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