Talk:LED lamp

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I stumbled on this article the other day, the disclaimers at the top are not joking, it's a pretty big mess. I'm going to do some cleanup. I've fixed some grammar / clarity things. Now it's time to remove all of the information that is elsewhere in wikipedia, we don't need a zillion copies of charts and conversions.

It also needs to be severely updated to reflect the current state of the technology. —Preceding unsigned comment added by 142.166.56.95 (talk) 19:53, 31 July 2008 (UTC)[reply]

Thanks for the warning (you don't have to), maybe you can combine the action with the shovel action on the left Light-emitting diode. Cheers Mion (talk) 13:10, 1 August 2008 (UTC)[reply]

There is also heavy use of 'current' and 'currently' and references to examples with no indication of time of writing. This is a fast moving area and several comments are already well out of date (15 January 2010) —Preceding unsigned comment added by Nickhoare (talk • contribs) 10:05, 15 January 2010 (UTC)[reply]

Sorry to split hairs but 'LED Lamp' IMO used to mean the LED itself (as used as a status indicator for example). This Wiki entry refers to LEDs used as compact solid-state light sources - 'luminaires'? Which are usually made up of clusters of individual LED lamps. 81.86.144.210 18:54, 14 June 2007 (UTC)[reply]

Within lighting engineering/design, "lamp" is the common term for "bulb" (and "luminaire" or "fixture" is the term for "lamp," as in "table lamp"). The individual LED can be referred to as a "device," which is incorporated in the ANSI/IESNA definition of LED. ^[1] Rdlpdx (talk) 22:36, 16 October 2009 (UTC)[reply]

DOE Say "pivotal emerging technology" link is http://www.netl.doe.gov/ssl/

I don't know how to cite stuff, but found above link. Tim S

Why the disputed tag? Someone put it in the article, but there is no actual discussion about it. 129.130.48.10 -

• i know, but from 7 - history to 14 is from 2001 and has to be rewritten anyway. reg. Mion 02:20, 11 April 2007 (UTC)[reply]

Compact fluorescent lamps cannot be thrown away like regular Incandescent light bulbs when they extinguish or break because of the mercury in CFLs. What are the environmental hazards of SSLs? Can they be thrown away? Can they be recycled? If they break (I know they are harder to break), can they be vacuumed up? -57.67.16.50 13:41, 20 April 2007 (UTC)[reply]

Well, the BEST way to recycle an SSL would be to salvage the LEDs -- most would still be usable, even if at reduced efficiency/light output (if the SSL has been on tens of thousands of hours) -- and use them for other things (indicators etc rather than primary lighting).-69.87.200.219 00:25, 11 May 2007 (UTC)[reply]

Projections and future hopes are nice, but the main practical subject here is the economics, and the reader wants details of current economics. There are pictures of LED lamps. How much do they cost? How much light do they put out? Etc. Other WP articles are now saying that LED is now economic, as general incandescent replacement. We need some place, here or somewhere, that goes into the details.-69.87.204.36 13:56, 27 April 2007 (UTC)[reply]

And leave a note on my User talk:Mattjs page telling me how to do it as I come across this problem quite alot at wikipedia. Regards, Mattjs 17:22, 29 April 2007 (UTC)[reply]

There are special 120VAC LED assemblies now generally commercially available, intended for retrofit in incandescent EXIT signs. Search for 'LED "exit sign" retrofit'. Cost is $5-50 for 1-3 watt assemblies in red, green, or white. Socket adapters available.-69.87.203.202 01:33, 12 May 2007 (UTC)[reply]

This source sells LED bulbs for $25-75, as floodlights, 2-12 watts, 30-120 LEDs: Note the flim-flam they engage in to rate them, since LEDs are good for directional lighting, not so good for general illumination:

-69.87.201.141 11:54, 12 May 2007 (UTC)[reply]

This source has a dozen various LED lamps with standard bases, 1-5W, up to 120 lumens: And very nice detailed spectral graphs: The prices are here, $10-40: -69.87.203.248 02:14, 16 May 2007 (UTC)[reply]

Someone was offended by a discussion-page posting, and removed all mention of this recent product introduction. So, if you are interested, you'll have to read the history for 11may07. Then, if you are really interested, you could try to write it in a way that the censor will leave... (Note: what one person may sincerely believe is "blatant spam", another person may sincerely believe is "just trying to contribute useful, relevant info".)-69.87.201.141 11:48, 12 May 2007 (UTC)[reply]

120VAC LED nightlights are now generally available cheap. What are typical lumens/watt? How are they wired/designed/built inside -- do they use bulbs in sockets? How does the light output compare to standard 4W/7W incandescent E12 candelabra nightlight bulbs? What is the lumens/watt for those traditional bulbs?-69.87.204.2 20:56, 15 May 2007 (UTC)[reply]

All the LED and other lighting articles should include a handy reference sidebar along these lines:

• Color Spectrum

Red 780 - 622 nm

Orange 622 - 597 nm

Yellow 597 - 577 nm

Green 577 - 492 nm

Blue 492 - 455 nm

Violet 455 - 390 nm

-69.87.203.97 13:10, 20 May 2007 (UTC)[reply]

Wavelength-nm Color Name

over 1100 Infrared

770-1100 Longwave NIR

770-700 Shortwave NIR

700-640 Red

640-625 Orange-Red

625-615 Orange

615-600 Amber

600-585 Yellow

585-555 Yellow-Green

555-520 Green

520-480 Blue-Green

480-450 Blue

450-430 Indigo

430-395 Violet

395-320 UV-A

320-280 UV-B

280-100 UV-C

Color Temperature Example

2000° Gaslight

2470° 15 watt incandescent bulb

2565° 60 watt incandescent bulb

2665° 100 watt incandescent bulb

2755° 500 watt incandescent bulb

2900° 500 watt Krypton bulb

3100° Projector type filament bulb

3250° Photo Flood

3400° Halogen

3900° Carbon arc

4200° Moonlight

4700° Industrial smog

5100° Hazy weather

5500° Sun 30° above horizon

6100° Sun 50° above horizon

6700° Electronic Flash

7400° Overcast sky

8300° Foggy weather

30,000° Blue sky

Notes on LEDs -69.87.203.97 15:13, 20 May 2007 (UTC)[reply]

"2Ø1/2 Half intensity angle (deg)"

This is a very confusing subject, that needs explanation. It needs typical graph curves. LED etc beam width seems to be usually speced at full beam width, side-to-side, down to half of peak (central) power. But sometimes it is given as +/-, which seems to maybe be the angle from the central axis to one side? Please help!-69.87.203.97 13:25, 20 May 2007 (UTC)[reply]

Size Millimeter

T1 3mm

T1 1/2 4.8mm

T1 3/4 5mm

T2 1/2 8mm

T3 1/4 10mm

(is this the main diameter of the body of the LED?)-69.87.204.47 23:18, 21 May 2007 (UTC)[reply]

Yes, it's the diameter of the main body of the lamp in eighths of an inch, so a T1 lamp is 1/8 inch = 0.125" = 3.175mm in diameter.

Atlant 15:52, 22 May 2007 (UTC)[reply]

We should probably mention, the standard round LED shape has a flared flange at the base, in addition to the above main diameter (right?). The purpose of this is so the LED can be inserted into a round hole, grommet, etc mounting, from the back, and seated against this flared flange.-69.87.202.34 17:39, 22 May 2007 (UTC)[reply]

"LEDs have a MTBF (mean time between failures) usually in the range of 100,000 to over 1,000,000 hours. This is a long time for continuous operation, considering that a year is 8760 or 8784 hours. In practice, the useful measure of LED lifetime is its half-life; an LED is deemed to have reached the end of its life when the light output falls off to half the original.

When current flows through an LED junction the current flow is not uniform, resulting in small temperature differentials within the chip. These temperature differentials exert stress on the lattice, causing minute cracks to occur. These lattice defects accumulate with use, and reduce the photon conversion efficiency of the chip, thus reducing light output. The attrition rate varies from the LED material, temperature, humidity, and the forward current."
[1] Good intro to various LED tech details.

The Piranha/Super-flux data sheets at Jameco, from MCDelectronics, have good life-testing data sets at the end (see MCDL-1870XX (7.62 MM x 7.62 MM PIRANHA 40° - 40mA 664341.pdf), showing 10% intensity loss in first 1,000 hrs, and at least another 10% loss in the next 10,000 hrs. Additional 5% loss at elevated temps. Seems like most current LEDs may be significantly dim after 50-100,000 hrs! -69.87.204.14 15:04, 22 May 2007 (UTC)[reply]

I have seen white LEDs that have dimmed significantly after 2 months of use in a lighting application. The appearance of the yellow phosphor is different after use. I have seen no discussion of the impact the use of phosphors in white LEDs on their operational life compared with LEDs that do not have phosphor. Given that white LEDs are being promoted as a long life alternatives, based on figures like those here, I think more information is needed to a true picture of the life of some types of LEDs. -(someone wrote sometime)

Note: one year of continuous use is approx. 9000 hours.

We need some photos of prism-separation of LED light.
These are interesting resources:

• Supplement: Build Yourself a Simple Hand-Held Spectrograph good sample spectra
• SPECTROSCOPY FOR THE SCHOOL build a simple spectroscope from a CD
• Lighting Reference Guide – Understanding the Theory lighting design reference tables
• Craig Johnson's ledmuseum hundreds of detailed spectra, of different kinds of lamps/bulbs esp many LEDs -- but the infrared seems to not be fully included, and what about calibration?

Although the fancy versions of these instruments can cost thousands of dollars, any prism or diffraction grating can manifest these behaviors, and they are all around us, even the surface of a CD. Edmund Scientific offers a variety of Spectrometers and Spectroscopes in their Light Analysis category for $1-50. They also offer info on:

• Build Your Own Grating Spectroscope
• How Diffraction Gratings Work

[2] -69.87.199.97 11:43, 26 May 2007 (UTC)[reply]

What are the best sources of detailed reviews of LED devices?
What are the best forums that discuss LEDs in great detail?
What circuits are used in commercial multi-LED lamps?

What are the best circuits for DIY experimentation?
Some resources:

• Lighting up your model great illustrated diy LED/electronic basics
• DIY LED lighting Guide 24

Posted by Matthew Sun, 26 Feb 2006 LED lighting is becoming increasingly popular in ... household lighting. This article intends to be a comprehensive guide to their advantages, powering them, and creating dimming solutions.

* Why use LED lighting?

* Powering your LEDs with a DC source

* Using an AC source to drive LEDs

* Dimming your LEDs (with PWM)

* Purchasing LEDs

basic circuit discussion

• How to make your own LED bulbs.

By claude, Posted on Sun Jan 28th, 2007 a tutorial to making factory-made-look-a-like LED bulbs. about converting regular GU4(MR11) halogen bulbs to LED bulbs 12V 22-LED very detailed photos good discussion of line-voltage circuits (non-tech)

• Led master class; pt 1 (theory)

By commanda, Section Light Posted on Fri Apr 20th, 2007 constant current sources Extended discussion of circuit theory and practice

• Anyone design 120V AC LED Lighting??

By clone477 Posted on Wed Oct 5th, 2005 Anyone design 120V AC LED Lighting?? serious theory/discussion/experience

• How To Make MR16 LED Spotlights

Find out how to make your own LED spotlight bulbs 12VDC 22-LED Aluminum sheet, superglue, hotmelt good assembly photos

• How to build a 1,024,000 mcd portable light by yetion Oct 1, 2005; battery bike light
• Here is Plans for the LED Cave Light, Revised 11-20-01
• HOW TO - Luxeon LED caving lamps 1-LED battery microcontroller
• http://www.solidstatelighting.net/

-69.87.203.17 00:04, 28 May 2007 (UTC)[reply]

• LEDTechInfo links to LED tech info

-69.87.201.66 13:22, 29 May 2007 (UTC)[reply]

• How-Tos & Construction Driver circuits etc.
  

OddOne's White LED Information ("OWLI") - info on homebrewing LED projects, LED news...

-69.87.200.80 00:42, 15 June 2007 (UTC)[reply]

you need what kaid of lamp —Preceding unsigned comment added by 116.230.203.149 (talk) 15:41, 5 January 2009 (UTC)[reply]

The simplest way to drive an LED from line-voltage AC is with a large series resistor, which functions as a current source. Very inefficient, due to power loss in the resistor.

We could also drop line voltage to a low voltage to drive an LED with an AC capacitor. We can calculate power in the capacitor by V x A, but the result is not real watts - the answer is ideally all "imaginary" VA? In the real world, how do we calculate power dissipation in real capacitors used thus: how hot they would get, what would be safe design, etc? For example, if two LEDs are anti-parallel, and you want the total average current through the pair to be 20 mA, from a series capacitor, at 120 VAC, what capacitance is needed, what capacitor types would be appropriate, and would power issues in the capacitor be a concern?-69.87.204.197 13:34, 28 May 2007 (UTC)[reply]

This is a question about caps rather than LEDs. The answer is there is zero power dissed in the cap, hence it doesnt get warm. However your expensive LEDs wont last long on such a circuit. Tabby (talk) 04:23, 18 January 2008 (UTC)[reply]

This is not a theoretical question. This is a practical question, about a real-world LED circuit. "Zero power" in the cap is the theoretical answer. The real world does not work that way. What is the actual power dissipated in the series cap? And why do you think the LED won't last in such a circuit? It should last fine, if it has proper protective circuit design and cooling. -71.174.180.243 (talk) 02:55, 16 June 2009 (UTC)[reply]

Multi-chip LEDs are common. About four 20 mA chips are often combined in one four-pin so-called piranha or super-flux package. However, these are usually internally wired in parallel, making good current-sharing hard to achieve, and making them hard to drive directly from line voltage. Series-wired packages seem very rare. But the Osram OSTAR line offers up to six chips in series, for a nominal voltage of 20 V. They do seem very expensive and high-powered.[3]

"They comprise six chips, with the option of a matching lens. The 2 cm x 2 cm high-flux LED with lens provides 410 lm at 2700 K, 460 lm at 3000 K and 520 lm at 4200 K, in each case from an operating current of 700 mA. Their power input is 15 W.[4] -69.87.204.119 01:05, 2 June 2007 (UTC)[reply]

It's been quite an interesting year for the white LED industry, with mayor players trying to catch up among them, and significantly improving efficiencies in the meanwhile. There are already available "cool white" parts with efficiencies over 120 lm/W, and several manufacturers with even better chips down the pipeline. See, for example, the following data sheets:

http://www.cree.com/products/pdf/XLamp7090XR-E.pdf

http://www.lumileds.com/pdfs/DS56.pdf

http://www.seoulsemicon.co.kr/_homepage/home_kor/product/spec/W4218X.pdf

All of the above parts are commercially available from many sources, and already integrated into end-user products.

When an article starts comparing non-existent devices that are just figments of an excited imagination praying for more funding to todays products, with no allowance for the future improvements in those too, its time for some serious reality checking. This article as it stands needs to come all the way back down to the ground, to fact. Tabby (talk) 11:49, 6 January 2008 (UTC)[reply]

Yes, feel free to start. Mion (talk) 12:12, 6 January 2008 (UTC)[reply]

Maybe some time I'll have time to tackle the rest. Remaining sections look in need of relatively hard editing. Tabby (talk) 10:31, 11 January 2008 (UTC)[reply]

"It is currently impossible to replace filament lamps with equivalent LED lights due to thermal considerations. To achieve greater success a new type of LEDs will be needed with either much higher temperature tolerance or much higher efficacy."

This is a key point about LEDs, and one of the 2 main reasons why LED lights dont put out as much light as mains filament lamps.

If you're going to remove something, really you need to give a reason, otherwise its just wasting people's time. Tabby (talk) 20:29, 1 February 2008 (UTC)[reply]

I know its news until its in production, so maybe under research ? [5]. Cheers Mion (talk) 16:50, 4 February 2008 (UTC)[reply]

Unfortunately I dont understand your comment. Tabby (talk) 12:17, 15 February 2008 (UTC)[reply]

"In addition, mercury is detrimental to health, and should the lamp break, exposure to the substance can be hazardous."

The average human contains a few grams of mercury. Fl light mercury content varies, but is in the milligram range. Perhaps this is why no government anywhere in the world considers it hazardous. Tabby (talk) 12:17, 15 February 2008 (UTC)[reply]

i think the mercury part is about CFL's, it doesn't belong on the LED page, and there is a lengty EPA mercury page [6]. Mion (talk) 18:40, 15 February 2008 (UTC)[reply]

I removed the following table because it is nothing but wild speculation from a body wishing to assure and maximise its funding.

Bear in mind that both LEDs and fl lighting are improving as years go by, and comparing a wildly optimistic, non-existant, impossible hoped for future light source to today's fluorescent products is hard to regard as realistic in any way.

"The following chart, derived from information from Sandia National Laboratories, compares a perfected SSL device (to be released before 2025) with incandescent and fluorescent lights"

Technology	Future solid state lighting	Fluorescent	Incandescent
Luminous efficacy (lm/W)	200	85	16
Lifetime (kh)	>100	10	1
Flux (lm/lamp)	1,500	3,400	1,200
Input power (W/lamp)	7.5	20	75
Lumen cost ($/klm)	< 2	1.5	0.4
Lamp cost ($/lamp)	<3	5	0.5
Color Rendering Index (CRI)	>80	82	95

I put it here because this table surely deserves inserting in wikipedia somewhere, not as a reality based comparison of technologies or products, but rather to illustrate how wildly LEDs are currently being hyped, and to illustrate how people are wililng to swallow just about anything if the right person says it. Tabby (talk) 12:53, 15 February 2008 (UTC)[reply]

yes agreed on, but it was speculation in 2001, (the date of the table), it sure needs proper updating, before it goes back. Mion (talk) 18:35, 15 February 2008 (UTC)[reply]

If you know of a reason why a piece of wild speculation belongs in a wiki article I'd love to hear it. Re updating, nothing significant in it has changed since 2001, its still the same blue sky it was then. Even basic known facts in the table are wrong, let alone the imaginary stuff. Tabby (talk) 18:55, 21 February 2008 (UTC)[reply]

"The current generation of LEDs, which employs mostly blue LED chip + yellow phosphor, has a CRI around 70, which is much too low for widespread use in indoor lighting. More research & development is needed to improve this."

The solution has been known for over half a century. It is simply a question of cost cutting with uncompetitive products. Tabby (talk) 13:04, 15 February 2008 (UTC)[reply]

• • It is hoped future SSL developments may add further advantages, such as higher energy efficiency than existing technologies.

Currently, however, there is no SSL on the market that can be offered as a true replacement for incandescent or fluorescent lamps, despite marketing claims. White LEDs produced today are relatively high cost, making them uncompetitive, and practical LED lamps today are not as bright as traditional lighting due to cost and thermal issues.

However LED technological development continues apace, and it is hoped that future developments in LED technologies may address most of these issues.

Based on a study conducted by the Department of Energy (DOE) and the Optoelectronics Industry Development Association (OIDA), it is speculated that by the year 2025, SSL may well be the preferred method of illumination in homes and offices. Study at Cambridge University, England is puts forward 2012 for the take off of widepsread use of LED lighting.

Up to the last sentence was from 2001, the last sentence isn't referenced and is also mentioned in the bbottom of the article. Mion (talk) 19:05, 15 February 2008 (UTC)[reply]

":Up to the last sentence was from 2001"

It isnt, its a recent edit, but so what either way? Its either correct or not, and it is correct. Its also germane, as the average reader comes here with the usual LED marketing hype in their minds, and this addresses it, enabling reader understanding.

Do you have any qualifications in this subject? Tabby (talk) 18:59, 21 February 2008 (UTC)[reply]

This simply isn't true as I have used a strip lighting unit which was had a remote control dimmer in an office block I was working in 15 years ago. The unit was made by Philips. Can someone get this verified because I am 110% sure I am right 77.100.16.146 (talk) 04:01, 3 February 2009 (UTC)[reply]

I don't see the article claiming there are no dimmable fluorescent lamps; there is "Full dimmability – unlike fluorescent lamps...", which is true - dimmable fluorescent lamps cut off completely when dimmed to a certain point, and "Most fluorescent luminaires are not compatible with dimmers", which is also true. —EqualRights (talk) 13:45, 3 February 2009 (UTC)[reply]

This article and the Light-emitting diode articles overlap a whole lot. My best guess is that this article is supposed to cover replaceable lightbulbs where the light is generated by LEDs rather than incandescence or fluorescence. If that is true, then many of its sections should either be moved to the light-emitting diode article, or just deleted. Examples include:

• All of the History section, except for the last paragraph on Sentry Equipment Corporation lighting its factory (although that may merit removal for other reasons)

• All of the "Technology overview" section on how individual LEDs are manufactured so they output different colors (i.e. half of the section)

• Most of the "Driving LEDs" section, except for the information on powering from the mains (i.e. 3/4 of the section)

• Most of the "Research and development" section, except for the final paragraph on the new Cambridge University bulb (i.e. about 2/3 of the section)

That would cut this article's size approximately in half.

I'd do this myself, but the surgery would be drastic, and I'd rather get some feedback before I do so. If my assumption about the purpose of this article is incorrect, please let me know exactly what this article is supposed to cover, and why it needs to be separate from the light-emitting diode article. -- Dan Griscom (talk) 22:50, 22 February 2009 (UTC)[reply]

Please clean this article up.. started moving some refs inline, then stopped after seeing your comment. gioto (talk) 14:14, 25 February 2009 (UTC)[reply]

OK, I've done a broad pruning and rearrangement, cutting about 1/3 of the article. What remains is pretty good, although of uneven quality (e.g. the Comparison to other lighting technologies section is seriously confused). There's a lot of tweaking to be done: tweak away. -- Dan Griscom (talk) 01:50, 28 February 2009 (UTC)[reply]

There are 23 different LED-related pages, and I think there should be less than half that many. I've started a discussion on this at Talk:Light-emitting_diode#An_absurd_number_of_articles_involving_light-emitting_diodes; please come and join in. -- Dan Griscom (talk) 03:09, 3 March 2009 (UTC)[reply]

I've merged in the geobulb article and developed the section on the LED light bulb. This a product of my recent adventures researching the LED bulb replacements. I've decided that at the moment such bulbs are a little too dim and a little too costly for my normal household use. I hope this will change in the next year or two. I will leave it to others to check that the merge is o.k. and to redirect the Geobulb page. Bdushaw (talk) 01:18, 7 February 2010 (UTC)[reply]

The geobulb-section claims that:

This lamp was reported to be the most efficient LED light bulb on the market at the time of its introduction. This bulb was never commercially available, however

Which is confusing: How can you be the most efficient on the market, if you're not actually on the market? "not comercially available" means it wasn't actually possible to buy the bulb, right ? How can one claim that a device which one cannot actually buy, is nevertheless "on the market" ? What market would that be, precisely ? --Eivind Kjørstad (talk) 12:44, 11 February 2010 (UTC)[reply]