450 watt LED - Page 1
Forum section: electronics / general

author: ovnr
author_rank: Frequent Contributor
timestamp: December 17, 2017, 11:10:34 pm
content: Probably a nice LED. I honestly wouldn't buy a "Yujiled"-brandedanything, however.Excitingly high efficiency too - 48 lm/w.If you actually wantall the light, try Citizen'sCLU550 series- abs. max. rating is 595W, spitting out some 80k lumens (actual efficiency isn't spec'd at max power, but at 50% you're looking at 140+ lm/w).

author: Kjelt
author_rank: Super Contributor
timestamp: December 17, 2017, 11:15:15 pm
content: Where are these used , what application, there must be a huge heatsink attached to keep the temperature within specs?

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 18, 2017, 12:01:57 am
content: Quote from: Kjelt on December 17, 2017, 11:15:15 pmDid you watch the video? The heatsink is the size of a large motor with a fan inside.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: December 18, 2017, 05:16:56 pm
content: Quote from: ovnr on December 17, 2017, 11:10:34 pmDo you even know what those Yuji LEDs are? You seriously cannot compare them to those Citizen LEDs for their intended purpose.They have a minimum CRI of 95, making them as close to daylight as you can expect to get. And they are much smaller than those Citizens, which is good for focussing.This comes at the expense of lower efficacy, but hey, if you're in the film, photo or television industry, that's a small price to pay.

author: ConKbot
author_rank: Super Contributor
timestamp: December 18, 2017, 05:25:03 pm
content: Quote from: RobK_NL on December 18, 2017, 05:16:56 pmHey now, lets not let facts get in the way of comparing a CRI 70 led to a CRI 95 LED. Both are trash compared to the maximum (100 percent efficiency) of 683 lm/W, if you don't care about spectrum

author: ovnr
author_rank: Frequent Contributor
timestamp: December 18, 2017, 06:07:49 pm
content: Quote from: RobK_NL on December 18, 2017, 05:16:56 pmI did watch the video. Yes, the light emitting surface is smaller - 19mm diameter compared to 33mm. That also increases the power density to even more preposterous levels (on a package level, 0.69 W/mm² compared to 0.41 W/mm², and if you only look at the LES, 1.76 W/mm² for the YujiLED and 0.69 W/mm² for the Citizen). That's pretty uncomfortably high, and I'd be a bit worried about getting the heat spread out well enough so that the dies in the center don't get fried.As for the efficacy: It's dreadful. There are LEDs withbetterlight quality - CRI of 97 and R9 of 90 (compared to 95/80 for the YujiLED) which manage ~100 lm/w, liketheseCitizen LEDs. OrtheseBridgelux LEDs (97 CRI, 93 R9, ~110 lm/w).My point is simply that there arebrighterLEDs, more power-hungry LEDs, and as I mention above, LEDs with both better efficacy and light quality. Thus I don't find the YujiLED product to be entirely impressive - the cooler seemed fairly well engineered, however.

author: Kjelt
author_rank: Super Contributor
timestamp: December 18, 2017, 07:11:07 pm
content: CRI is not applicable for leds, there are new standards in development for leds.

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 18, 2017, 07:18:36 pm
content: Quote from: Kjelt on December 18, 2017, 07:11:07 pmWhat? That makes no sense. Color Rendering Index applies to all light sources, even the sun and fire.

author: Kjelt
author_rank: Super Contributor
timestamp: December 18, 2017, 09:57:19 pm
content: It makes perfect sense if you realize that CRI is measured by a sensor(s) which has problems with lightsources with only peaks in its spectrum as leds do. It was explained in a light course a few years back.While CRI in fact is the way humans perceive the color rendering which no sensor can do.Nowadays you see leds with fosfor which gives it a more broad spectrum and they score higher on the CRI.

author: ovnr
author_rank: Frequent Contributor
timestamp: December 18, 2017, 10:05:11 pm
content: Sure, CRI isn't perfect, which is also why the R9 (red color index) value is often reported separately.It's still the industry standard way to compare light sources, and what "everyone" uses. I'm sure it'll be replaced by something more accurate in time, but I'm not holding my breath. Besides, the issue is fairly complex, as you have to account for the differences in how humans perceive color, but also how a camera sees it (given the importance of quality light in the film industry).

author: Corporate666
author_rank: Unknown
timestamp: December 19, 2017, 07:23:07 am
content: Quote from: ovnr on December 18, 2017, 06:07:49 pmYou're shitting on a product you don't understand and know nothing about.The Yuji LED is a very targeted product, and they are a very reputable company, so your first post of "I wouldn't buy a Yuji anything" was totally inappropriate and ignorant. They are a very highly regarded LED and phosphor manufacturer, and their LED's are widely used in the movie/photography industry, as well as hospitality and food (supermarkets/delis, etc). There is a lot more to it than R9 values, and if you check their actual products, you'll see they have higher CRI LED's that more closely match actual daylight spectra than anything else out there I am aware of. They can also provide 95 minimum CRI LED's at 5600k CCT. If you delve deeper and look at the Rf ratings of their LED's, they outperform what else is available.As for this specific LED, it has R values in the mid-high 90's across the board. It also has a minimum 95CRI in all CCT's from 2700k to 5600k. And it has tiny color temperature shift and chromaticity shift over time. The thermal resistance of this sucker is 0.04C/W which is why it can be so small, and that's also another of it's selling points - smaller, meaning more packaging options, less money spent on optics, and better lumen maintenance over time.Now of course the applications for this specific LED are very niche, and the applications for Yuji's LED's are niche in general. But saying their LEDs are unimpressive because look at this Citizen LED or this Bridgelux LED is like when someone posts the specificiations of the new Lamborghini and someone says "that's nothing... my uncle's friend has a 1989 Toyota with a turbo that will blow that thing away". Apples and oranges.

author: ovnr
author_rank: Frequent Contributor
timestamp: December 19, 2017, 10:34:31 am
content: Quote from: Corporate666 on December 19, 2017, 07:23:07 amI'm shitting on a product that - at best - is atinybit better (light quality-wise) than its competitors. Also, color me entirely unsurprised when I noticed that YujiLED has no distributors. Period. Doesn't really sound like a massively big player in the area, and it explains why I haven't heard of them.Incidentally, their graphs show why the efficacy is terrible: They're using UV emitters - probably 405nm chips - instead of blue emitters.QuoteReally? Comparing a LED for high-end architectural lighting and the movie industry to... LEDs for high-end architectural lighting and the movie industry is apples and oranges? The Bridgelux Decor series would like a word, for instance. Incidentally Bridgelux also offers a 5600k LED with a CRI of 97 (the BXRC-56H10K0-D-74). It does 128 lm/w. And the datasheet for the 500W YujiLED does list it as having a R9 value of just 80; while that may be a mistake, it's their mistake.

author: Corporate666
author_rank: Unknown
timestamp: December 20, 2017, 12:42:20 am
content: Quote from: ovnr on December 19, 2017, 10:34:31 amAnd the fact that you are shitting on it for being "a tiny bit better" is proof that what I said is correct - you don't understand the product and don't know anything about it by your own admission. So why shit on it because of the name and country of origin and just assume it's crap? You were mistaken in your assumptions about this company - Yuji is not one of those Shenzhen factories cranking out junk LED's using fake Cree dice... they were more of a phosphor specialist whose niche is in the absolute highest quality light output possible who got into LED's to offer end-to-end solutions. They are a big player in THEIR niche. It is a small niche but it does have substantial crossover into the high end of the commercial lighting market (museums, art galleries, high-end residential lighting, some commercial lighting such as high end car dealerships, some restaurants, etc).QuoteTheir highest CRI LED's (98CRI) use violet dice which drops the blue spike you get when using a blue die. Efficacy suffers, but again, this is the niche - the absolute highest quality light. As you know, CRI - even expanded CRI that lists R values across the board - does not tell the whole story. They also have blue die LED's that have guaranteed 95CRI with excellent color quality across the spectrum. These have better efficacy at a cost of light quality.QuoteYes, apples and oranges.This particular LED you are crapping on is not comparable to the Citizen or other LED you listed as being better. The whole point of this one is light density per surface area in conjunction with light quality. This is achieved with the dice, phosphor and thermal resistance of the packaging. For lighting a factory floor, that's irrelevant. For many commercial lighting applications, it's irrelevant. For some applications, it's critical - and those are the kind of applications where the designer is even thinking about a $500 LED. You compared it to the Citizen CLU which is just silly... again, that's like looking at a Lamborghini and saying "pffft, my uncle has a turbocharged Toyota that will blow this thing away". Apples and oranges. I am not sure where you are seeing the datasheet - their website shows only the datasheet for the 100W version and it doesn't list R9 values, but the site itself shows R9 values in the mid-high 90's for this LED.As for the Bridgelux Vero's... I know them well and I have used thousands of them over the past few years. I have also used many thousands of the Yuji LED's (not the ones the OP mentioned, but I have used thousands of Yuji COB and smaller 5730 and 3030 SMD LED's, both violet die and blue die). I like the Bridgelux parts very much, but throwing out that specific part number Bridgelux doesn't change anything. First, have you ever tried to buy one of those? You can't. Nobody has them in stock. In fact, nobody has any Bridgelux 97CRI LED's in stock above 3000k in any package. I am not convinced that 5600k/97CRI LED even exists other than in a datasheet. Digikey says you can get them with a 50MOQ, but I've tried and the order gets cancelled unless I am willing to commit to a MUCH bigger order. Bridgelux does have 90CRI (typical) LED's out in the wild, but if you look at their datasheets, those 90CRI LED's only have R9 values of 50.The standards for film/video/photo lighting are 3200k/5600k (less important than some years ago but those two specific numbers persist)... and Bridgelux doesn't have a 3200k super high CRI LED. The 5600k one is unobtanium.Yuji on the other hand, you can go to their website right now and buy their 98CRI (Re) LED's, and you can get that LED with those specs in any color temperature you want... 2700k, 3200k, 4000k, 5000k, 5600k, and 6500k. Or you can go with their 95CRI min (Re) /97CRI typical LED's that use blue dice and are the equivalent to the Bridgelux LED's - and again you can buy them in any of the available color temperatures up to 6500k with those specs without special orders or waiting.Lastly, as you probably know, even expanded CRI is largely outdated these days. For film/video, TLCI is taking over, and both Bridgelux and Yuji publish this data. Bridgelux' 5600k/97CRI Vero LED's have a TLCI rating of 97, Yuji is at 99.Yuji is not some fly-by-night Chinese company making dubious quality LED's. They have an excellent reputation and are most definitely a leader in their niche of the industry. You haven't heard of them, fine... but you shouldn't shit on them just because you haven't heard of them and because they are Chinese. Their product is top-notch.

author: Red Squirrel
author_rank: Super Contributor
timestamp: December 21, 2017, 07:29:45 am
content: Imagine these in a RGB setup for some serious Christmas displays.I could see these being used in applications like stadium lighting actually. You would have multiple of these behind a large set of lenses to project on the field. And then multiple bunches of them throughout.