AndyL Posted March 20, 2005 Report Share Posted March 20, 2005 Hey all, Spent the day drilling plexi like mad... Finally managed to get exactly what I wanted - and realized I was using the wrong matierial (8 sheets of plexi destroyed... over 2400 holes marked and most drilled by hand... (Did I mention my hands hurt?) and the damn things not going to work right) Anywho... rant over with... I need a 10x16 ish hunk of preferably finned aluminum, or heatsink material. Anyone know a good (think cheap) source? I found a few local, but I'm not going to pay 300+$ for a hunk of metal. Andy Quote Link to comment Share on other sites More sharing options...
Vallisneria Posted March 20, 2005 Report Share Posted March 20, 2005 Do you mind if i ask what you are making? Quote Link to comment Share on other sites More sharing options...
AndyL Posted March 20, 2005 Author Report Share Posted March 20, 2005 LED lighting array for the new 5g reef. The acrylic holds heat in too well (LEDs burn out quickly under excessive heat), and with 300 of them, I'd rather not run the risk. Andy Quote Link to comment Share on other sites More sharing options...
ÐÉÅÑ Posted March 20, 2005 Report Share Posted March 20, 2005 What is producing the heat your concerned about? Quote Link to comment Share on other sites More sharing options...
AndyL Posted March 20, 2005 Author Report Share Posted March 20, 2005 The LEDs themselves. They put out quite a bit of heat, and excessive heat causes them to bun out long before their rated life is used up. Andy Quote Link to comment Share on other sites More sharing options...
ÐÉÅÑ Posted March 20, 2005 Report Share Posted March 20, 2005 Ok, I was under the impression that leds give off little to no heat. Quote Link to comment Share on other sites More sharing options...
AndyL Posted March 20, 2005 Author Report Share Posted March 20, 2005 Compared to other lighting options, they are low heat - but they are definitely not "no heat". Andy Quote Link to comment Share on other sites More sharing options...
Beermaster Posted March 20, 2005 Report Share Posted March 20, 2005 (edited) LEDs cause little or no heat if your only putting 3volts to it, no if your thinking of pumping 12v though every light yea that will generate to much heat and probaly burn the epoxy around the diode itself they produce virtually no wasted energy in the form of heat. LED lights can be misleading in some ways . . . . As far as light output; they consume ( those presently widely available on the market ) about the same amount of energy to produce a given amount of light; as a high efficiency fluroescent. So, while you can hold one in your hand and feel "no" heat; they do indeed produce heat at about the same level as fluorescents do. We do not PERCEIVE the heat; simply because LED's tend to be very good at producing high intensity in a shaped beam . . . not light in all directions. This makes them very useful for small task lighting, or uses where the light is really only needed in a narrow beam. Large area illumination is NOT their forte; and while it can be done it DOES get expensive . . . and the energy consumed to do so will be on par with fluroescents doing the same task. As a perfect example of what I'm saying; consider traffic lights, or now the tail lights on vehicles . . . . tradtionally done with incandescents. The LED equivalents that can be had do NOT produce the same amount of light . . . . but they DO produce a high level in the specific direction / plane that it is needed in. Traffic lights need to be very visible directly head on . . . their illumination to the sides drops off rapidly . . . LED's can serve this function and other similar ones very well . . . Also know that LED's are for the most part quite tolerant of running them at higher currents / temps than they are spec'd at . . . while not a good long-term idea; it can produce amazing amounts of light . .. at the expense of LED lifetime. Heat is one of the major killers of LED's; over time their output will drop . . . and running them hot will accelerate WHEN that will happen. It may matter in your application; or it may not. Their lifetime is VERY long; so using one in a way that drops it's useable lifetime to half it's normal one; simply will not matter in some circumstances. If the LED in your flashlight lasts only 10 years instead of 20; it just may not really matter . . . . Edited March 20, 2005 by Beermaster Quote Link to comment Share on other sites More sharing options...
AndyL Posted March 20, 2005 Author Report Share Posted March 20, 2005 Of course everything is relative. pushing 3.2v 20mA though a 5000mcd LED isn't going to create much heat, But these new 20,000mcd LEDs running at their rated 3.2v and 30mA definitely puts out some heat. No real way to measure it - but I'm willing to guess the 300 of them will put out heat on par with a couple NO flourescent bulbs. Keeping them cool just helps prolong their life (And the good 20,000mcd white's aren't cheap usually running at least 0.50us$ each) The blue 10,000mcd units I've got are even cooler running (3.2v 20mA) Andy Quote Link to comment Share on other sites More sharing options...
HOSStile Posted March 20, 2005 Report Share Posted March 20, 2005 Could you not put the light array inside a plexi box that would keep the water away from the leds and make the whole thing easy to clean. For cooling mount 1 or more muffin fans on top. I have a bunch of 2 inch 24 volt dc fans you can have or you can source the 12 volt ones for about 10 bucks at a computer store. Harold Quote Link to comment Share on other sites More sharing options...
bucky Posted April 1, 2005 Report Share Posted April 1, 2005 could you elaborate on the use of the heatsink. i.e are you actually mounting the LEDs right in it or are you just going to use it for heat disappation. If you are going to use it for heat disappation you could look into getting a few heatsinks from a computer store and mount them with some thermal compound. if you are looking for aluminum just let me know the exact size and i will see what i can do? I used to be a welder and still have a few friends out there. Quote Link to comment Share on other sites More sharing options...
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