SMD LED - Page 1
Forum section: electronics / projects

author: madmaxbryan
author_rank: Contributor
timestamp: May 21, 2011, 04:55:41 am
content: Can anyone put a name to this SMD LED? i got a few of them in a grab bag, all i know so far is that when i apply 3.3v the are a very bright white. the clear dome is solid and not soft like the luxeon rebels, also, there is a metal ring around the base of the dome.

author: Psi
author_rank: Super Contributor
timestamp: May 21, 2011, 08:18:22 am
content: They look kinda similar to the CREE leds herehttp://besthongkong.com/product_info.php?cPath=19_53&products_id=549

author: Zero999
author_rank: Super Contributor
timestamp: May 21, 2011, 08:56:45 am
content: I'm not from the US so I've no idea of the dimensions of the LED because I don't know the size of the coin in the picture.I assume the bad didn't have a part number printed on it?Where did get them from? A friend, ebay?If so it's pot luck, they could be anything.If you want to know the maximum forward current, test one to destruction. Build a constant current source, connect the LED to it, ramp up the voltage whilst measuring the voltage across it, until the LED gets too hot and smokes. The absolute maximum rating will probably be half the destructive current and the recommended forward current will be between half and three quarters of the maximum rating. Also look at the voltage across the LED and compare the voltage/current characteristic with a range of white LEDs, if the forward voltage of a standard white LED is 3.5V under the recommended forward current, the chances are you're safe running your LEDs at whatever current you measure when the voltage is 3.5V.Quote from: Psi on May 21, 2011, 08:18:22 amI've never bought fromwww.bestofhonghong.combefore, has anyone else? How can you be sure they sell genuine parts? I'd be wary of buying from some Chinese website, they might not be Cree LEDS, even if they're supposed to be.

author: RayJones
author_rank: Frequent Contributor
timestamp: May 21, 2011, 09:58:00 am
content: And looks like the latest vapour ware from CREE here:http://www.elektor.com/news/231-lumen-per-watt-led-shatters-led-efficacy.1818849.lynkx?utm_source=UK&utm_medium=email&utm_campaign=newsBut I doubt the OP's are 231 lumens/watt

author: Psi
author_rank: Super Contributor
timestamp: May 21, 2011, 11:09:02 am
content: Quote from: Hero999 on May 21, 2011, 08:56:45 amI've bought 10 CREE leds from them to use for room lighting. They have been running at their max current of 1A as my room lighting for over 5 years now.Soifthey are fake CREE's they are pretty damn good fakes.

author: Rufus
author_rank: Super Contributor
timestamp: May 21, 2011, 05:07:46 pm
content: This is a CREE XR-E.The lenses are hard but are set in clear silicone rubber and move a little if you poke them.

author: madmaxbryan
author_rank: Contributor
timestamp: May 21, 2011, 05:42:23 pm
content: the ones i have are identical to the pic you just posted Rufus, they have the same green lines and brown lines next to the pads, the same "+" in the brown line, the metal ring looks identical too. the only difference is the lense on mine are solid as a rock and dont move or "squish" like most smd led lenses do. But im going to have to assume these are either cree xr-e or xr-c cool white leds, unfortunately not the 231 lumen ones that RayJones posted, now im curious as to where i can buy a 231 lumen cree led and how much it will set me back, i want one!!!

author: Rufus
author_rank: Super Contributor
timestamp: May 21, 2011, 06:01:42 pm
content: CREE XR-E and XR-C LEDs definitely have the die encapsulated with silicone rubber (or similar) and hard plastic lenses stuck on top of the rubber. If you get superglue near them the lenses fall off - lol.I try not to poke them but on the ones I have the lens will move a little, it isn't held in place by the metal ring.The one in the photo is the cool white 1A version.