two "strange" type of 5mm led?

two \"strange\" type of 5mm led?

i have found this 2 type of leds on ebay but i don't know if the tech. data are true or the seller lie...

1)
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=66952&item=3840055049

how can run at only 1.8-2.4v? if it is true i can drive it with a single cr123a or a cr2032?

2)
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=66952&item=3840054595]http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=66952&item=3840054595

how is possible that this led can output all this light? 21 lux on a 23° beam... i can substitute the led in all my flashlight and have a great improvement with this...

Re: two \"strange\" type of 5mm led?

I always take the "specs" of anything I see on eBay with a huge grain of salt. The voltage for the first LED is definitely wrong-an occasional white LED may have Vf of around 2.8V, but most are in the 3.0V to 3.6V range. As for the second one, the specs are certainly believeable given the high price (relative to the $0.25 or so that white LEDs usually go for). 21 mcd with a 23° beam angle is ~2.7 lumens, and if we assume 3.5V for the forward voltage then we get an efficiency of close to 40 lm/W. That is certainly reasonable for a high-grade white LED these days. One thing I hate with a passion is the way many sellers specify beam angle as +- x degrees. In this case, I'm sure +-23° doesn't mean 46°, but there are LEDs where the seller specifies a 20° beam angle as +-10°. The only way you know for sure in these cases is to actually purchase the LED.

Re: two \"strange\" type of 5mm led?

and I don't trust people that borrow pictures from other places and can't be bothered to take a pic of the actual product (or at least admit that the pic is not of the actual product) but that fancy pic of 3 3mm LED's is the same as on

http://www.fiberopticproducts.com/Leds.htm

That website, I don't know where it comes from originally, but it's certainly not of the LED"s they are selling.

Re: two \"strange\" type of 5mm led?

The "Reverse Current" specification is incorrect for both LEDs too. For one, it's listed as 20mA; for the other it's 30mA.
I believe it should be approximately 10µa (10 microamps) maximum.

The photograph in that first listing reminds me of one I butchered up for The LED Museum a few years ago; and that's still floating around out there. I saw it just a day or so ago on another website.
I think it may have originally been used on the Nichia America website; but I could be mistaken.

(Edit, a moment later)

Here's the graphic I used:



Does that white LED look a little familiar now? /ubbthreads/images/graemlins/wink.gif

Re: two \"strange\" type of 5mm led?

I've noticed plenty of bogus specs on 5mm LEDs out there.

ISP's website features some LEDs that calculate astounding efficiency figures - P/N 10W4DHCB-H features ~112 lm/W and P/N UFO-4W a more modest 79.5 lm/W.

Yeah, right. I think they misplaced a decimal point or several, or their beam angles are way off.

Re: two \"strange\" type of 5mm led?

thanks for the warning

and now where i can buy really bright leds for replace the ones in my x-nova lights?

Re: two \"strange\" type of 5mm led?

Here's my rudimentary LED DB.

If threre's a LED in there with efficiencies much more than 30 lm/W, odds are the specs are inflated or just plain wrong (with one exception being "unobtainable" Lumileds bins). If I've said "bogus specs" in the Notes column, odds are it's fiction I invented for the calculations to work, or highly suspect data on the spec sheet. Some of the worst offenders tend to be ISP, Roithner Lasertechnik, and some resellers like superbrightleds.com.