High powered LED pendent

[chucelli]

I'm not sure to which LEDs you are referring, but these have no internal reflectors. The chip is a two dimensional square less than 2mm in diameter. Light output from this tiny squarish plane is 180˚. If the chip was mounted on a reflective surface, it would not benefit from a reflector sitting behind the chip. Optics designed for this application are mounted within ≈120˚ field and contain a built-in reflector and lens. The amount of light lost with the use of optics are insignificant relative to the amount that would otherwise end up being on the walls of the room when run without optics. In any case, optics are not necessary as many early users have discovered that their systems needed to be turned down or mounted higher due to the intensity of these LEDs. However, optics definately gives you cleaner and stronger output.

-R

[jaesun]

This is a nice build! Is that a VGA cable? Cool idea. Nice and clean.

 

As for the dimming, you will need use Pulse Width Modulation. Relatively simple with a 555 timer IC - if you can solder a LED together, you can definitely solder the PWM circuit. LEDs need to be on at full power. You can't dim it by limiting the current or voltage. LEDs, however, can be turned off and on rapidly. Like thousands of times in a second. By controlling frequency and length of the off and on cycles, you can control the brightness since the cycles will blur together to the human eye (and I assume corals and fish too).

 

Another advantage of LEDs that hasn't been mentioned here is the downward scalability. If you ever wanted a 1 gallon with corals (even SPS) for your desktop, it's possible with LEDs.

 

Deli's 1 gallon PicO from Nano-Reef

 

[chucelli]

yes, that is a DB9 connection It allows up to four channels (blues, whites, fan, aux).

[Av8BlueWater]

Do you have a link to your RC thread?

What type of LEDs?

[paenian]

actually, you can dim LEDs by adjusting the current; in fact, they are significantly more efficient at lower currents.

 

You can also combine current sources, i.e. half-drive two strings with one driver for an hour, then switch on the next driver for higher brightness.

 

Paul

[jaesun]

actually, you can dim LEDs by adjusting the current; in fact, they are significantly more efficient at lower currents.

 

You can also combine current sources, i.e. half-drive two strings with one driver for an hour, then switch on the next driver for higher brightness.

 

Paul

 

oops. my bad. I realized this after I posted. My buckpucks regulate the current for my LEDs.

Edited February 26, 2010 by jaesun

[chucelli]

Av8BlueWater,

sorry for the late reply. I just noticed this thread today after Jaesun posted...

My RC thread is located here.

It contains links to some of the most informative info regarding LED lighting. You can also check out my article at ReefAddicts here.

I think it was posted earlier in this thread, but I am using Cree XR-E emitters from the Q4 bin. I recently switched to using Q5 bin emitters for new builds because suppliers are no longer carrying Q4s.

-R

Edited February 26, 2010 by chucelli