Brightest 2.4 volt LED?

[zmoz]

What would be the brightest LED I can find for 2.4 volts? (2 AA NiCds) I would go for a Luxeon and micropuck, but I'm looking for something under 50ma.

 

[James S]

You could run a few colored, red, yellow, amber type LED's at that voltage as they have a lower forward voltage than the blue or white ones. Usually 2.1v or so if memory serves. You're not going to be able to run more than 1 or 2 and keep the power usage under 50ma.

For white you're going to need a booster circuit of some kind to raise the voltage to the 3.4 necessary to light a white LED. This is going to send your efficiency out the door, but maybe not too badly. A micropuck is going to be WAY out of the range you're talking about since it delivers 350ma at 75-80% efficiency so probably about 450ma or so minimum draw. A single LED driver circuit could be built with pretty good efficiency, but the single transistor ones I've built have been more like 50 to 60% which is not all that good /ubbthreads/images/graemlins/wink.gif There is LOTS of discussion about that stuff around here, if quick searching doesn't turn anything up let us know I'm sure we can dig up the specifics in old threads if you want.

 

[zmoz]

What would be the brightest color that I could use? And then who makes the brightest one of that color? /ubbthreads/images/graemlins/smile.gif

 

[Jonathan]

I'd take a look at the red/orange 'Superflux' devices. Made my Lumileds, the same company that makes the Luxeons. These are smaller (75 and 150mA) devices.

I believe the Inretech uses this for one of their red/orange drop-in devices.

-Jon

 

[Zelandeth]

I'll have a rummage about to see if I can find anything useful, red and (as I remember amber) have a far lower Vf than the Newer green/blue/white.

Okay, forget what I just said about green.

I just dug out three Kingbright "Extreme Brightness" 5mm LED's (Red, yellow, green, water clear, untinted case in all examples) and set my power supply to 2.4v, stuck a resistor in there to restrict the total current to 50mA, and hooked the LEDs up, the result came out looking as follows:

NOTE: Beamshot was taken from a distance of ~1 foot with the LED's simply stuck in a protoboard, no reflectors, optics or other fancy things used.

Green seems to be a slight bit brigther to the eye, but the red would be better for night vision preservation if that were an issue, and would probably give you light for longer as the batteries run down.

(That pic actually shows accurately how it appears to the eye for once! Finally getting my head around this camera)

Not sure where else there are available, but I know they can be found at Maplin Electronics (Where I got these from)

Part Numbers:
Red = "N69AJ"
Orange = "N70AJ"
Yellow = "N71AJ"
Green = "N72AJ"

£0.49 (~ US $0.60) each.

 

[zmoz]

Ok...I think I've decided on red. I would like to find a place in the US to buy from...so what is the absolute brightest red LED (5mm and where do I get it? /ubbthreads/images/graemlins/grin.gif