Crazy LED question

[novahobbies]

....is there any reason I couldn't use simple screen framing aluminum as my heat sink for a small number of LEDs? This would also be actively cooled by a venting fan blowing over it. I have access to that material fairly cheap here. Or am I nuts? Doesn't seem much different than the aluminum L-bar I've seen people use.

 

[2quills]

Don't see why not. But I also dont think that I'd need to explain to you that it's only going to be marginally effective as a heatsink compared to a nice sized hunk of alluminum.
But if you're willing to experiment and then come back and share some info on how burning hot they will probably get under high powered leds then I'd certainly love to hear what you have seen.
That way we can compare the temperature readings of the leds and diy sink with the recommended operating temperature of the leds from the manufacturers data sheets to see if its a wise idea or not.

 

[novahobbies]

LOL Dude I love your roundabout ways of saying "not a great idea."

I found some c-channel aluminum for a decent price. Not as good as I can get the other stuff, but a nicer material. I'll probably go with that instead.

 

[siptang]

Rick - text me some pics, I want to pick your brain a bit.

 

[2quills]

Quote:
Originally Posted by novahobbies http:///t/394769/crazy-led-question#post_3513782
LOL Dude I love your roundabout ways of saying "not a great idea."

I found some c-channel aluminum for a decent price. Not as good as I can get the other stuff, but a nicer material. I'll probably go with that instead.
Depending on circumstances I wouldn't necessarily call it a bad idea. For instance, like using x number of much lower power leds for color or creating ambient lighting. But for most purposes as far is this hobby is concerned in regards to the products that are currently popular to use then perhaps it's not such a great idea if longevity is of any real concern to the builder.

 

[novahobbies]

Hey Richard, sorry I didn't see your post! What pics did you want?
OK, here's what I picked up. I have some 3/4 inch aluminum c-channel for the light bars, and I'm using 3/4 inch flat cross braces to support it over the existing fixture.
Now, I was originally going to use 3 red, 2 green, and 1 UV LED for each side. I'll have 6 red, 4 green, and 2 UV bulbs total. This is supplemental light for a 110g tank that's 29 inches deep (figure 27 inches to the sand bed), and the lights are 6 inches away from the water.
For the LED gurus here....do you think this is too much red? I know Siptang was concerned about the amount of red, and I'd love if others weighed in as well. RIght now I'm toying with the idea of cutting my lights down to 2 red, 2 green, and a UV per side, and I can always add in another red later. It's a tough decision...I've seen prepackaged LED fixtures these days with more red in them, but as Sip very wisely pointed out....we have to factor in algal growth when planning these.
Here's a pic of the unit as originally planned.

 

[acrylic51]

I think you might be a bit heavy on the red....Wouldn't do more than 2 red, 2 green, but IMO up the UV......If you do 1....Not even worth the hassle you won't see anything.....They are easily "washed" out by blues, so unless you supplement heavier on the UV it's pointless, and technically they aren't "UV" bulbs as most would think.....I only mention that aspect since someone might mention UV is bad.

 

[siptang]

I agree with shawn.

 

[novahobbies]

Shawn, are you thinking 2 red and 2 green per side? Or total?
Yes, I think I'll have to order 2 more UV bulbs. Shame they're the priciest, LOL. At least I get get them from the States...I think it's time for a RapidLED order.

 

[siptang]

1 per side is wha I have and I wish I had 12 more uvs... I have 10.

 

[novahobbies]

WOW. That's a lot of UV! I think my wife might smack me silly if she sees me buying too many more LEDs....LOL...

 

[siptang]

Uv is not a strong light rick. Like shawn said above, it gets washed out very easily.
I gave you few colors any ways so just say its for something lol.

 

[acrylic51]

Nova I think the ratio could be questionable.....It comes down to how hard your running/pushing the reds and greens and are they adjustable meaning can you dial them in and out.....I've been doing a lot of reading lately through a couple threads I follow, and 2 seems like a good number.....I think those color combinations of 2 reds per pod are pretty close to what a Radion is running.....Again depends really if you can control them or what else is on that driver and how hard they are run......As far as UV agree the numbers have to be higher to see any gain.......But it comes down to driver choices and what your eye likes.....
Personally when I do build my LED rig it will be in pods similar to the Radion, but will have (2) reds and (2) greens.....I'm looking at a total of 8-9 channels.....I'm even considering adding yellow into the mix....