Still a bit of work ahead, but I now have the components for assembly & testing. The wiring needs some serious cleaning up, but I'm still experimenting with different options to drive the LEDs. The 3 dimmers work very well so I'll order a few more of them for added flexibility in controlling the intensity of each colour. I'm close to their current limit of 8 amps each, so there's a safety factor to consider. The 12VDC constant current drivers I ordered should arrive within a week, so I'll be able to see how they might fit into the scenario.
A summary of the fixture's current config:
-Three rails of nine 10watt LED arrays each for a total of 27 LEDs,
-Two outer rails each have five 10000K White & four 452-455NM Royal Blue,
-Center rail has five 460-470NM Blue & four 6000-7000K White,
-Three 8 amp Dimmers, one controlling all the Whites & one each for the Blues & Royal Blues,
-One heatsink with fan per LED,
-One 250watt 12VDC power supply,
-Terminal boards, wiring, stainless steel hardware & aluminum angle stock,
-Mahogany veneer wood frame (I scored the wood real cheap in the clearance pile at Windsor Plywood).
The fixture weighs just over 12 lbs, or approx 5.5 kg. I ran it last night trying each colour on it's own & in various combos, including full on. Although the calculated wattage with 27 ten watt LEDs is 270 watts (more than the power supply max wattage), the energy monitor showed around 230 watts with all LEDs & fans running. I attribute this to the fact that I didn't run them at their full voltage/current. I dialed the voltage on the power supply down to 9.9 VDC & using each dimmer, further lowered the voltage delivered to each colour to < max rated forward voltage. When time permits, I'll perform current measurements on each LED to confirm they're operating at or below max rating.
One of 3 dimmers I used during the initial test. These are actually sold to dim 12 volt SMD LED strips, but they work fine with the 10 watters, provided you mind the current rating:
The entire assembly. Wiring will be cleaned up, shortened, more terminal boards added & dimmers mounted remotely near the power supply:
The 'bright' side:
Side view showing the Mahogany veneer frame. This should look pretty good with some finish & trimmed with moldings:
As far as the test run goes, I very much like what I saw last night & don't think I need to modify anything with respect to colour blending & spacing between the LEDs. I used a couple of 2x4s to rest the fixture on the rim of the tank, much closer to the surface than it will eventually hang. Quite anxious to get it completed now & start experimenting with height above water. The Royal Blues in particular bring out a flourescence in my LPS & soft coral that I've never seen with my current MH/T5HO set up.
Some pros & cons having reached this point:
Pros (as I see them anyhow);
-DIY, so I can repair or modify any part of the fixture myself with parts readily available & relatively inexpensive,
-Fewer LEDs required than with the more common 3 watt builds,
-Not as heavy as builds with massive heatsinks,
-10 watt LED forward voltage is in the 9-12 VDC range, more flexibility in choice of drivers, power supplies etc. Easier to adapt to off grid power, solar, wind, battery etc.
Cons;
-DIY, not everyone's cup of tea,
-Noise from fans (didn't seem bad at all during test run),
-Limited controllability compared to the fancier manufactured fixtures, i.e. dimming is manual at this point,
-I have no measurements as far as light output etc, so experimentation & time will be needed to confirm suitability. Manufactured fixtures have all the testing done & data available. My build is a best guess as to what I require.
More to follow as additional components arrive & I finalize assembly. I plan on ordering a couple more power supplies so that I can run each colour on a separate timer to get some form of sunset, sunrise effect. I also need them to keep from overworking the single 250 watt supply. Still pondering whether soldering the heatsink fans directly to the LED contacts is a good idea or whether I should cut the leads & run them at the full 12 volts all the time. Stay tuned.