The Luxeons are a special case. The dies are designed to really handle significant amounts of current, and as such will tend to get quite hot. 350 mA is quite a bit of current. Your standard LED from Radio Shack expects 10-20 mA, high brightness models may go as high as 50 mA, but that's still not a whole lot in the grand scheme of things. For the amount of light they give off, LEDs are quite electrically efficient when compared to standard bulbs

 

yup, at 20mA we could run luxeons with no trouble. just like a regular LED; but luxeons are meant to be run at 100-1000mA. they just need proper cooling, doesnt matter how you cooled a normal LED, itd be dead at like 30 or 40mA.

I have a infrared heat detector now tho; so once I make the final prototypes, I can test them to ensure they are running at a safe temp(tho still VERy hot, but no different than a normal bulb; ~150-200degrees)

 

Ares, I'm not sure where the heat is dumping into (open air, etc.), just make sure they will have a decent supply of fresh air. If not and they're running for a while, you'll start to see some product returns after a couple of months. When Luxeon says they're good for 1,000 hours at a specific amperage and temp, they mean just that, and you shouldn't expect much more than that. If it's financially wise, I suggest going with a higher model and heavily underpowering it.

 

thought of that, but prices would be like 200$ a bulb. heh that wouldnt work.

I may drive them at even less than 100mA. rather than one high power underdriven, rather underdrive multiple low power. atleast there would be better light dispersion there; and a little more heat dissipation.

 

You could try pulsing the power...pulse at 350 mA @ 1kHz with a 10% duty cycle. That should give you most of the brightness of 350 mA with about the same heat as pumping it at 50-100 mA.

It would add an insignificant amount of cost ($5-$10) since the complexity of the circuit would be quite low, but allow you to get the brightness you need.

 

well size would become an issue. right now this particular application is for a bulb; you could tap into the current feed outside of the bulb and do that; but most people wouldnt want to have to do anything but swap the bulb; and starts to get complicated if your making different bulbs with different resistors for those that want to modify their wiring to allow for higher currents vs those that dont.

 

Actually, you could do it all on the same board that contains the Luxeon LEDs. You would still have the standard light bulb connector, but the piece that plugs in would include both the LED and the minimal control circuitry, all powered by the same socket connection....no need for extra wiring.

 

between the LED and the resistor there isnt a whole lot of room. the whole thing has to be no more than 1" in diameter; and not too tall either or it wont fit.

 

Any pics of the space this is going into? I can't believe there's nt enough room to put in some circuitry, either to the side or between the socket and the LED.

 

Eugh... the bulbs have a nice low profile to them so they won't stick out as much, but then we have to strategically place the 1W resistor in such a way it fits and doesn't short anything at the same time.

 

yeah the resistor takes up more space than anything. 2 or 3watt would be even better; but that REALLY doesnt fit.

 

Cripes, how big is this 1W resistor?

 

big enough; but mostly an ackward shape for an small ackward spot.

 

You can easily get surface mount resistors in 1W packages that are roughly 0.25" x 0.10". You should have no problem fitting that into the spot...