Needed a light boost for my fluval chi and thought I could do a custom one for cheap. All you need is:
Constant current power supplies are recommended, but I wanted to try it out with a constant voltage supply because I had the resistors and power supply lying around from other projects. The resistor does dissipate power but its negligible.
2. A few
. Make sure you use an LED array calculator to calculate the value of the resistance you want (available online). For this particular array I used (2) 1.5 ohm resistors in series to make a 3 ohm resistor. Make sure your resistor is safe to pull a higher current! Mine was rated for 5 amps.
I used 3 watt LEDs. They seem to be a little bluer than the rated 6000-6500K, but thats okay. I liked these because they already had 120 degree lenses attached to them.
5. Electrical Wire
6. Solder and soldering iron
7. Electrical tape (optional)
1. Drill holes in the Chi lid. I made two different sized holes. A smaller one big enough for the lenses to fit in that went all the way through, and a larger one that went half way through for the LEDs to sit in.
2. Wire and solder LEDs in series according to the wiring diagram obtained at this site
3. Attach LED array to the resistor. When I first turned on the light I was using only one 1.5 ohm resistor, but the lights got REALLY bright and HOT (315 F measured with my thermocouple) as they were on the upper end of their allowable voltage. This dropped the LEDs from 3.7 to 3.3 forward voltage and 260 F. I still think the temp is too high so I may attach some little fins to them to better draw the heat out. We'll see how they hold up.
4. Tape the LEDs in place. You could alternatively tack bond them and the wires.
5. Hook up the power supply and LEDs to the dimmer.
I only felt like doing one of the arrays for now, so when I get time I'll do the other side. These guys really do a good job lighting up the tank and I'm really really pleased and impressed. Quick and dirty. I don't mind all the tape and disorganization because the lid is above my head and I can't see any of the wiring. Once I get the other lights up I think this will be a solid tank for mid-high light plants.