How to Build a DIY LED Aquarium Light, Part IV
Building Your Array
In this article, the finale of this series, I'll show you how I built my LED array for my 29 gallon BioCube saltwater aquarium. In Part I, I talked about why you might want to build your own array; in Part II, I went over the essential supplies you'll need to build an array and where you can purchase them. In Part III, I discussed how to plan out your LED array.
Now, it's time to pull it all together. I'll go over what I did and how I built the array, and hopefully give some advice that will help if you decide to build an array of your own.
Parts and Tools Used
Before I get going, it might be helpful to see my complete parts list. I'll separate it out by where I purchased the items:
Purchased from LED Group Buy:
- Bridgelux Royal Blue LEDs x12
- Bridgelux Neutral White LEDs x 12 (Only used 10)
- Cool Blue (470nm) LEDs x2
- Deep Red (660nm) LEDs x2
- Turquoise (495nm) LEDs x2
- True Violet (420nm) LEDs x6 (Only used 5)
- Inventronics 40w 700 mA drivers x3
- 10k Ohm 1/2 watt linear potentiometer x3
- 12v 500mA power supply for fan x1
Purchased from RapidLED:
- 6" x 9" Black Anodized Aluminum Heat Sink x1
- Arctic Alumina Thermal Adhesive x1
- 6 Wire Nuts (I ended up needing more)
- Y-shaped Hanging Kit
- 3-Prong Power Cord x3
- 1 AA Battery LED Tester
- 7' Black Wire, #20 AWG stranded wire
- 7' Blue Wire, #20 AWG stranded wire
- 7' White Wire, #20 AWG stranded wire
Purchased from NewEgg:
- ROSEWILL RFA-120-K R x2 (120mm case fan)
Purchased from Home Depot:
- 10-pack Insulated Waterproof Wire Nuts
- 4-pack 1.5" corner braces
Purchased from Radio Shack:
- Project Enclosure (8"x6"x3") x1
- Project Enclosure (6"x4"x2") x1
- Rosin Core Solder, 2.5 oz x1
- Weller 40w Soldering Iron
- Black and Decker Cordless Drill
- Wire Stripper/Cutter, #8-#22
- Ratcheting Screwdriver
Step 1: Test the LEDs
Before I went any further, I tested each individual LED with the battery-powered tester. To use the tester, I touched the red cable to one of the positive terminals, and the black cable to one of the negative terminals. If the LED was good, it lit up. The video to the right shows how this works.
NOTE: 3W LEDs are very bright. I made the mistake of looking at a couple of the LEDs when I tested them. I was seeing spots for about 15 minutes.
Manufactured LED Aquarium Lights
Step 2: Prepare the Heat Sink
I printed out the layout I'd prepared earlier, and secured it over the face of my heat sink. Earlier, I'd altered the layout and placed an X in the center of each LED circle. I placed a nail over the X and gave it a solid tap with my hammer. This left a small but noticeable mark on the heat sink, big enough that I could use the mark to position my LEDs.
Before continuing, I blew off the face of the heat sink with a can of air.
Step 3: Prepare the Work Station
I live in an apartment, so I didn't have a garage I could work in. I set up a card table right next to one of my windows, opened the window up, and set up a fan to air out the work station. I filled a small plastic container with water and placed a new sponge in it; this was to clean off my soldering iron as I worked. Last, I cleared off the card table and laid a piece of cardboard over the surface, to protect the table from any soldering residue.
Step 4: Glue the LEDs
Thermal adhesive typically comes as a two-part solution. After mixing the solution, I had about ten minutes to work before I would need to mix up another batch.
Each LED only requires a small dab of mixed solution, about the size of a pea, in order to attach to the heat sink firmly. Using my earlier markings on the heat sink, I glued the LEDs down. Using my earlier markings on the heat sink, I glued the LEDs down. After putting a quick dab of adhesive onto the back of the LED, I gently pushed the LED in place, rotating the LED around to spread the adhesive evenly. I had my layout diagram at hand so that I could put each LED in its proper place, with the terminals facing in the correct direction.
Step 5: Tin the LED Connections
"Tinning" is a short way to say, "melt some solder onto something." In this case, I tinned the terminals on the LEDs. It would have been somewhat easier to do this before I glued the LEDs, but heat is the death of LEDs. I wanted the heat sink to absorb the heat of the soldering, rather than forcing the LEDs to absorb the heat.
Step 6: Cut, Strip, and Tin the Wires
I measured from LED to LED and cut a strip of wire for each connection. Next, I used my wire strippers to strip off about 1/2" of insulation from the end of each wire.
I placed each piece of wire in my clamp, and tinned each wire end. Tinning the wires before soldering the LEDs together improves the electrical connections.
Step 7: Solder the Connections
Now that the preparations were in place, I could begin the meat and potatoes of this project. Working on one circuit at a time, I soldered each wired connection in place, always going from positive to negative.
I was glad that I had pre-tinned the connections; I had to hold the wire in place with a pair of needle-nosed pliers while the other hand worked the soldering iron. After getting the initial melt, I then used the pliers to push the wire deeper into the molten solder. When completed, the solder completely covered the wire ends.
This was a very delicate process; a slip of the soldering iron could ruin an LED or give me a nice pleasant burn. It also took some patience; I had to use a small soldering tip to get the precision I needed on my crowded heat sink, so the solder didn't melt terribly fast. But after a few nights of work the array was all soldered together.
After soldering, I tested each connection by using my LED tester to run a current across each connection. Most of the connections were strong enough the first time around, but a few needed to be redone. Satisfied that I had a well-soldered array, it was time to prepare the drivers.
How does a potentiometer work?
You might be wondering how attaching a knob to your driver makes your LEDs brighter or dimmer, or what all those terms mean.
For purposes of this discussion, a potentiometer is an electronic device that changes the voltage of an electronic signal based on some external factor - in this case, how much the knob on the potentiometer is turned.
The driver sends out a static 10v signal on the yellow wire. The signal passes through the potentiometer and is altered by the potentiometer. Depending on how far the knob is turned, the purple wire carries a signal back to the driver between 1v and 10v. This voltage is then used to send electricity out to the LEDs, and they light up at a certain brightness depending on how much power they receive.
Step 8: Solder the Potentiometers to the Drivers
The next step was to solder the potentiometers to the end of the dimmer wires on each driver. There were three wires on each driver, matching up with three terminals on each potentiometer: the 10v input, the 10v output, and the ground. Because those are bound to get confusing, I'll refer to them from here on out as the green wire (the ground wire), the purple wire (the 1-10v output wire), and the yellow wire (the 10v input wire).
I first pre-tinned the terminals on the potentiometer. To the right, you can see a pot similar to the ones I used. The terminals are the small metal protrusions sticking out from the circuit board. I then soldered the wires from the driver (which were shipped pre-tinned) onto the terminals in the correct order. I soldered the green wire to the top terminal (or left terminal, depending on how you're looking at the pot) . I soldered the purple wire to the central terminal, and the yellow wire to the bottom (or right) terminal.
I then repeated this for each of my three drivers.
Step 9: Prepare the Project Boxes
I next prepared the project boxes for the drivers. This is a nice way of saying, "I drilled holes into my nice pretty plastic boxes."
In the front of each box, I had to drill out a hole for each potentiometer knob. So, one hole in the front for my smaller box, two holes for the larger box.
Next, in the rear of each box, I needed to drill out three holes for each driver: one for the power, one for the wire going out to the array, and one for the wire coming back in from the array. I then labeled each hole so that I could retrace my steps later if necessary.
I then drilled a bunch of holes into the lid of each box for ventilation, then I measured and drilled screw holes to attach the boxes to the shelf that was going to be their home. I screwed the boxes down and arranged the drivers inside of each box. After sliding the potentiometers into their new homes and holding them in place with the washer and nut that fit onto the knob, I then screwed the drivers into place within the boxes.
Step 10: Connect the Wires
At last, it was time for a crash course in wire nut usage. It turned out to be pretty simple to connect the various wires together using the wire nuts. First, I twisted the wires I would be joining together outside of the nut. Next, I slid the connected wires into the insulated wire nuts. Holding the wires firmly in one hand, I gave the wire nut a few twists until the connection felt solid. I gave the wires a few tugs to make sure they were held firmly within the nut.
It took me a few tries to get right, which led to a pretty goopy mess. Insulated wire nuts are filled with a non-conducting silicon gel. The first few times I tried to connect the wires in the wire nuts, the connection didn't take and the wires popped out, covered in slimy gel.
It's very important to connect the proper wires together. No matter what brand of driver you are using, there will be two wires that attach to your array. One wire, labeled V+, attaches to the first LED in a particular series. The other, labeled V-, attaches to the final LED in a particular series.
If the wires are attached to the wrong end of the LED string, the driver or the LED could be overloaded, completely destroying the LED or the driver. Thankfully, Inventronics, like most manufacturers, color-codes the wires to make it easy to connect the wires properly. For the Inventronics drivers, the V+ wire is red and the V- wire is black.
Unfortunately, one of the power wires is also black. Make sure that you follow the diagrams for your driver and make sure that you're using the correct black wire in your wiring. If you attach the wrong wire, you might not damage anything, but your LEDs will be severely underpowered and won't dim. I can neither confirm nor deny that I speak from personal experience on this subject.
The only really difficult part in this step was wiring up the power cords to the driver. I had to cut open the end of the cord, remove the insulation, locate the proper wires, and trim down the ground wire. The power wires had considerably more strands to twist than the other wires did, so that was more challenging as well. All in all, though, not too difficult.
Step 11: Turn it On!
At last, the moment of truth... it was time to plug it in!
I plugged in my surge protector and plugged each driver in, one at a time. I flipped on the power and...
I repeated the process for each driver. I did come across one stumbling block; as I alluded to above, I'd attached the wrong black wire to one of the LED strings. I didn't realize what the problem was at first, so I went back and resoldered that entire LED string before I finally figured out what the problem was. After calling myself several creative words for 'idiot', I fixed the problem and it worked perfectly.
Step 12: Hang it Above the Tank
Now, all that was left was to hang the array over my tank. I enlisted my wife, and we carefully took the array to hang it from the light hanger. I ran into another snag here: my hanging solution didn't work. The heat sink was supposed to have extruded slots for a hanging kit, so I had planned to hang it using those. However, while the slots were there, they had no way to actually hold the array onto the hanging kit. Had I tried to use that idea, the entire array would have hung by the wires for a few moments before the soldered joints failed and the array took a quick swim in my fish tank.
Necessity is the mother of invention, though, and within a few minutes I'd drilled some holes in the heat sink, installed some corner braces onto the heat sink, and screwed the hanging kit into the braces. That quandary behind us, we hung the array over the tank.
Step 13: Enjoy!
The hard work behind me, it was time to just sit back and enjoy the new lights! Here are some shots of the tank, before and after the new lighting. There is about a three month gap between the before and after photos, to give you an idea of how much growth these LEDs can give.
Also, don't let the camera fool you. For most of these pictures, I had to run the camera at extremely fast speeds to avoid completely washing out the colors. In real life, the LEDs are several times brighter than they appear to be in the pictures.