Hey guys,

I'm having an argument...err.... discussion about LED's and whether or not they are notorious for producing heat.

Who is right? Any resources would be great, thanks.

 

Hello,

Take a look here:
http://www.theledlight.com/technical1.html

A white led of 3.6 Volts at 30 mA will dissipate 100 mW.

Bertus

 

Typically they have about 10% efficiency which means that 90% of the power into them is given off as heat. This is better than a lot of other types of lighting, however LEDs can't tolerate high temperatures like flourescent or incandesant bulbs, so there is more than one side to the story.

http://en.wikipedia.org/wiki/Lighting_efficiency#Lighting_efficiency

 

The high power units need heat sinks. Figure 3.6V Vf at 700mw works out to 2.5W, the 1.4A units are double that.

In LEDs running at 20ma it is negligable, but there.

 

U know LED's can burn ur figures

 

U know LED's can burn ur fingures

AND they can burn you fingers too!

 

Sheeeeesh....
I need to get some sleep....
I am having too many typo's

 

most 5mm LED's can't generate enough heat unless you put too much voltage through them even some of the cheaper IR led's these days you can run them at up to 100ma and i've touched it and got stung (but no burn)....

however, the more expensive LED's, Cree Q5,R2,R3,R4 they all take up to 1000ma and without good heatsinking, YES they can and WILL burn your fingers reaching 150c at core junction temperature hence the reason for decent heat sinking.

Maximum junction temperature: 150°C
Maximum drive current: up to 1 A
Low thermal resistance: as low as 9°C/W

http://www.cree.com/products/pdf/XLampXP-E.pdf

(also, check out the Cree MCE, SSC P7, 3amp LED's, plus the new XPG, R5 leds)

 

The datasheet for every LED spec's its max allowed current which makes it hot.
LEDs are powered with current, not voltage.

I made a night-light with 36 Luxion SuperFlux LEDs that have a max current of 70mA but I used "only" 53mA. Boy oh boy oh boy did they get hot even when they were not at their max current and I housed them in a case full of holes.

 

The datasheet for every LED spec's its max allowed current which makes it hot.
LEDs are powered with current, not voltage.

I made a night-light with 36 Luxion SuperFlux LEDs that have a max current of 70mA but I used "only" 53mA. Boy oh boy oh boy did they get hot even when they were not at their max current and I housed them in a case full of holes.

Thats a bright night light! Juh-eez!

36 Luxion SFs for a night light... I use two 1300 mcd kingbright white 5mm LEDs @ 20ma and that was fine for not bumping into things around the house.

I would like to see a photo of that beast.

 

Thats a bright night light! Juh-eez! ....
I would like to see a photo of that beast.

At night it lights up my entire neighbourhood.
I housed it in the case for a compact cassette tape (the one on tne right side):

 

Audioguru, that's about the same amount of light you get from an SSC P7 or an MCE, it's not all that bright these days, the SST-90 (with lens) anyway if you want to see a real BEAST in action check out the youtube video below.

http://www.youtube.com/watch?v=VHEXz0g2iB4

 

Audioguru, that's about the same amount of light you get from an SSC P7 or an MCE, it's not all that bright these days, the SST-90 (with lens) anyway if you want to see a real BEAST in action check out the youtube video below.

Why do you talk in letters and numbers that don't mean anything to me?

 

I dunno, you did you mentioned you wired up luxon emitters to light up the back yard so i figured you knew something about flashlights guess i was wrong, but i did post a youtube video link....