LED pendent Gen2

[zygote2k]

Is it possible to lower the fixtures to within a foot of the water- say inside a canopy? What is the spread of the light in that instance?

[dbartco]

nice facebook bump that went out today on RA.

[chucelli]

fry_school101,

The fans keep the layer of heated air from staying around the heatsink. This, in turn helps the heatsink maintain ambient air temperatures. If the heatsink is kept cool, the LED junction temperature will also be kept within specs.

During the testing phase, heatsink temperatures did not get anywhere close to the max spec'd 80˚C. However, I did not have any accurate means to measure junction temperatures, so my design had to be conservative. Any air movement through the heatsink fins is enough to keep the heatsink at ambient air temperatures (≈71˚F or 22˚C). Without the fans, certain parts of the heatsink measured at ≈60˚C.

Also, since operating temperatures have a direct impact on LED light output, I wanted to make sure light output was never compromised, as any decrease in output would most likely not be detected by our eyes. In short, the fans are doing alot in cooling the LEDs.

 

zygote2k,

It is possible to mount these as close as you want. Do a search on RC or Youtube for "soundwave's" LED build. He has them mounted inside a canopy. Although I would definitely recommend the use of some kind of splash guard for the lights if that is your plan. Also the use of optics would have to reconsidered. Perhaps 80˚ optics could be used, but most likely at that mount distance, the best result will be no optics. Although IMO, no optics means lots of light is wasted (refer to my PAR measurements table). These examples can be seen clearly when you see a room completely lit up vs the same fixture lighting up a specific area (tank) only.

 

Doug,

I don't know what a facebook bump is, but it sounds good.

Thanks,

-Robert

[jtro]

Would love to see these in person or maybe some better pictures of the lighting what do you think they are 10k 14k 20k I didn't see that you answered lanman before but I night of missed it.

 

Thanks

Jim

[chucelli]

Jim, I could try to make it to the next social on the 23rd at the zoo. If we could arrange to have it over a tank, even better. It is hard to say what color conventional lighting they compare to. These definitely have a blue bias to them, however, they do not mute the colors like 20k lamps tend to do. The appearance of the end color can also be adjusted though different optics combinations. Lastly, the LED blue/white ratio can be changed to further change light color. However, the 50/50 ratio seems the most commonly used ratio, and I would say has a proven track record for excellent coral growth and color. "soundwave" or "menthol" are two RC names which come to mind when I think of good coral coloration (both use 50/50 ratio).

-R

[chucelli]

uploaded a video.

Color is a bit washed, but you can see what the light looks like on moving water...

-R

Edited January 16, 2010 by chucelli