The amazing magical LED: Has it really been fifty years already?

Next time I hear Coldplay festively crooning "May all your troubles soon be gone, Oh Christmas Lights keep shinin' on," I'd like to think that far from lamenting some lost love, they're paying solemn tribute to the humble but illuminating LED. The Light Emitting Diode celebrated its 50th anniversary this year. It's easy to …

[John Hawkins]

LED lighting instead of fluorescent 'haz mat'

Currently throwing out (aka 'recycling') those awful low energy fluorescent lamps I replaced the even worse incandescent lamps with many years ago. I didn't realise how dangerous fluorescent lamps were until recent years.

I *like* the cooler, more natural white light of good LED lamps, much better than the sickly yellow light produced by incandescent lamps. Guess people just don't like daylight, preferring instead something that is basically an industrial artifact from a time when proper light wasn't practical.

[Anonymous Coward]

Re: LED lighting instead of fluorescent 'haz mat'

What colour is the sun? oh yes, it's yellow.

Most people like warm light in the EU. In Japan they like white light.

[M Gale]

Re: LED lighting instead of fluorescent 'haz mat'

You'll find that our sun is mostly white, and that rayleigh scattering makes most of the light that hits this planet end up as a slightly blue colour during the daytime. "Yellow" is only relative to things like red giants and the super-hot blue stars that burn themselves up in a comparitively short time. Sol certainly puts out a whiter light than your average 2300k "warm white" CFL.

There's also a few stretches of road near me that are part of some government experiment for LED street lighting. Each pole has a cluster of some 5x5 or so grid of super-bright white LEDs. It works, rather awesomely well. Nice to be able to see in colour under a streetlight.

[alpine]

Re: LED lighting instead of fluorescent 'haz mat'

But the point is that the human eye is more sensitive to the red end of the spectrum rather than the blue. That's why years ago fluorescent lamp manufacturers spent lots of money developing the 'warm' tubes that are more human friendly than the cold raw tubes. The led lamp manufacturers have not yet got to this stage of development, which is why the light from them is currently so 'cold'. I'll start getting them when they make them human friendly!

[Anonymous Coward]

Re: LED lighting instead of fluorescent 'haz mat'

And the eye is more sensitive to the red end because of the hundreds of thousands of years of evolution where generations spent their evenings round the warm yellow light of the open fires...

[Dave 126]

Re: LED lighting instead of fluorescent 'haz mat'

>I *like* the cooler, more natural white light of good LED lamps, much better than the sickly yellow light produced >by incandescent lamps. Guess people just don't like daylight, preferring instead something that is basically an >industrial artifact from a time when proper light wasn't practical.

The power-efficient LEDs do not replicate the shape of natural daylight perfectly, they have their own bias. What people 'prefer' depends upon the time of day and the task in hand, and our circadian rhythms.The effect of different colour temperatures upon us is still being researched, but we know that, for example, fitting a 24 hour police control room boosts the concentration of the officers in the early hours of the morning. We also know that working night shifts under artificial lighting has been linked to rises in some cancers.

We associate red light with full bellies, sat around the embers of a camp fire, soon time to sleep zzz. I use a piece of freeware called 'f.lux', which changes the white balance of my monitor according to the time of day (by world location and calender, of course) so that 'white' on my monitor closer resembles a sheet of white paper that is held next to it- bluer during daylight hours, warmer when the room is artificially lit.

A local publican has replaced the hideous 12v halogen down-lighters above his bar (hideous because halogen bulbs were never designed to sit in enclosed spaces for thermal reasons... they prefer being suspended in space between two LV cables) with RGB LED units, which can cycle through a range of colours. Curiously, under their impression of an incandescent bulb, I can't tell a blue Rizla packet from a green one.

Second product plug: Tescos have a home-branded 2xAA flashlight with a CREE LED for £10. Brighter than anyone needs to walk to the pub across the fields, its fits in your pocket, and you can be more philosophical about losing it than you would a pricier branded model. I wish more cyclists on a budget would use them in place of the flashing white LED units that project next-to-no light and make it harder for a motorist to judge their speed and distance (the movement of a constant cone is easier to judge than that of an intermittent point light, duh). I use them with nickel metal hydride batteries, which are so much better than rechargeables were when I was a child.

[Anonymous Coward]

Re: LED lighting instead of fluorescent 'haz mat'

+1 for Cree LED torches. I've been buying them from eBay for a couple of years now and they are awesome. Especially when you ally them with 18650 batteries (which you can pack quite a lot of power into), you end up with a very bright and long-lasting torch that comfortably fits into a pocket. Too bright almost...with my current 1000 lumens (it claimed on the sales spiel) torch (£15) , you can't use it for close-up work and have to put it into low-power mode. It's comforting to know that I can signal passing aeroplanes if I feel the need tough (SOS mode).

[Vic]

Re: LED lighting instead of fluorescent 'haz mat'

I wish more cyclists on a budget would use them in place of the flashing white LED units that project next-to-no light and make it harder for a motorist to judge their speed and distance

Cyclists use flashing lights because they are more visible - our eyes are incredibly sensitive to movement[1], and a flashing light is perceived as movement, since flashing sources are incredibly new in evolutionary terms.

So although such lights make it a bit harder for motorists, they make it *much* safer for cyclists. At least we'll be seen.

Vic.

[1] Whether you're predator or prey, an awareness of moving things around you is kinda important...

[David Given]

Re: LED lighting instead of fluorescent 'haz mat'

Flashing lights are easier to *notice*, but the strobe effect utterly defeats the brain's ability to track movement --- extrapolation of movement can't be done and your brain will try to tell you the object is stationary. Strobes are used for exactly this effect on stage. Ever wondered why it's so hard to follow aircraft in the night sky? That's why.

So when I'm driving and I see a flashing bicycle light, I can see that there's *something* there, but I have absolutely no idea which way it's going or how fast it's moving.

In cities it's less of a problem as the cyclist is lit by streetlights and there's enough context so that I can actually see you. But if you're cycling in the dark, such as in the countryside, please, *please* don't use flashing lights.

[Vic]

Re: LED lighting instead of fluorescent 'haz mat'

> Flashing lights are easier to *notice*

And that is all there is to it.

> the strobe effect utterly defeats the brain's ability to track movement

That's still better than drivers not noticing at all. It might not be perfect, but it's by far the better solution.

> Strobes are used for exactly this effect on stage

That's at a much higher frequency. It's a different effect.

> please, *please* don't use flashing lights.

I always use flashing lights when cycling, and I always advise other cyclists to do so. As a motorist, I also prefer them as they are almost impossible to miss. Given the average level of observation shown by drivers, I don't intend changing my behaviour any time soon. Flashing lights are *significantly* safer.

Vic.

[Stoneshop]

Re: LED lighting instead of fluorescent 'haz mat'

The led lamp manufacturers have not yet got to this stage of development,

For values of "not yet" equal to "for several years already". It's the same principle as (C)FL, phosphors being excited by (near-)UV, so a lot of that research can (and has been) ported over. The manufacturing process for the light source is different, as is the environment for the phosphors, so that has taken a bit of effort to get right as well.

[4ecks]

Re: LED lighting instead of fluorescent 'haz mat'

I supply lighting for a living, and IMHO most customers don't have a clue as to what different light sources are available & to what use they are best suited. Most new houses have halogen downlights 'cos the "designer" thinks they look good, but the latest generation of LED sources are much better suited and although the initial cost is higher, more cost effective over their expected lifetime. Megaman GU10 retrofit at 4W and 6W dimmable (£12) & 50000hr life, or Aurora AU-FRL series @ 9W & 75000hr are viable candidates to replace 50W halogens.

However the main benefits of LED's are in commercial premises, where reduced maintainance costs will often pay for the initial outlay over the expected life of the installation, and then some.

[James Hughes 1]

Re: LED lighting instead of fluorescent 'haz mat'

@4ecks

Thanks for the references - need some decent LED GU10 replacements - got some cheap LED in the kitchen and they are not bright enough for some areas so still using incandescent. Also have couple of rooms with GU10 downlighters (PITA), on dimmers. Trouble is, I'd need 15 in total....

[Anonymous Coward]

Re: LED lighting instead of fluorescent 'haz mat'

This is untrue. Warm LED lights are now available because I have 9 such bulbs in my house. 5 GU10 replacements in the kitchen and 3 standard true 60 watt equivalents on the stairs and hall.

I still have some traditional GU10 halogens in the kitchen and you'd be hard pressed to tell them apart from the LEDs apart from the lack of heat and the fact the LED's are marginally dimmer.

Absolutely love them. A good quality of light, low energy use, hopefully a long life and an instant on at full brightness. Yes they do cost an arm still but like many on here I like the idea of exciting new tech and hopefully they will save money in the long term.

You just need to get the latest versions and not the last gen LED bulbs being knocked out in hardware shops and other places.

[Anonymous Coward]

"You'll find that our sun is mostly white"

Mostly frickin' hot, I think.

[Tom 7]

Re: "You'll find that our sun is mostly white"

cant bloody remember....

[Stoneshop]

Re: LED lighting instead of fluorescent 'haz mat'

your average 2300k "warm white" CFL.

You'll find that even warm-white CFLs are more like 3200K, trying to be equivalent to your average incandescent bulb (when not severely dimmed)

I find LED street lighting here to have a definite pale-greenish tinge. Apparently this has now been found to drive nightly critters, especially bats, ehm, batty, and the newest units have lost the greenish hue and emit a more whiter, slightly blueish light.

[Anonymous Coward]

Re: LED lighting instead of fluorescent 'haz mat'

"What colour is the sun? oh yes, it's yellow."

An object's colour we perceive is modified by our brains - particularly with an expectation of something being "white". Photographs often show colour casts because the brain is now accepting what the camera media recorded. Cameras that attempt to automatically correct their colour balance will try to render everything as a midday clear sunlight - destroying the atmosphere of sunrise/sunset shots.

So an indoor picture shows the very yellow cast of low temperature lights like candles or tungsten bulbs. It shows green for fluorescent lights. Natural daylight is "high temperature" white. Snow under a clear sky looks blue to a camera. Washing powders used to add blue colouring to fool the eye/brain that the result was "whiter than white". To get the effect of midday sunlight a camera flash has to produce what seems like a very white light to our eyes at the time.

You can see these colour casts in the natural light of a scene - if you look hard. Photographers have long been conscious about vegetation throwing a green pallor on someone's face. However most of the time the eye/brain tends to give us a corrected perception which seems "normal".

[Richard Cartledge]

Re: LED lighting instead of fluorescent 'haz mat'

Same is true in most of Asia, they like 'mahtab' CFLs not 'aftab' but sometimes have eclectic mixes of both.

[itzman]

Re: LED lighting instead of fluorescent 'haz mat'

Er no. Sunlight, by the time it gets through the atmosphere, is distinctly blue-white, largely because the sky turns blue, and actually, that's responsible for a LOT of the illumination we see by

Any photographer will tell you about the differences in 'colour temperature' between daylight, incandescent light and fluorescent light.

WE are simply conditioned to expect a lot more red in artificial light, ever since candles and gas mantles. and we got a lot more green with mercury vapour lamps. Now LEDS can be conditioned, tuned or combined to give any colour you want.

Give it time and warm white will be there .. if that's what you want.

[Phil O'Sophical]

Re: LED lighting instead of fluorescent 'haz mat'

> I didn't realise how dangerous fluorescent lamps were until recent years.

Dangerous? How? Are you referring to all the US scaremongering about the trace of mercury, where people suggest you need a full hazmat-suited contamination squad to clear up a broken bulb? Maybe if you're a building janitor clearing up several smashed bulbs per day you'll take additional precautions, but in a domestic scenario it's a bit like dialling 999 for a papercut.

The biggest problem with compact fluorescent bulbs is that the need for them to fit standard lampholders, which means that the "replaceable" part contains all the electronics to drive the tube. That is unlike traditional fluorescent tubes where the electronics/ballast was in the fixed part of the appliance. Throwing away (or even recycling) the electronics just because the tube has gone is engineering incompetence verging on the criminal. Only a politician could have mandated that.

LEDs aren't much better, although their lifespan mitigates the problem. Plain halogen bulbs are still likely to be the safest and most efficient solution, at least in a climate like the UK.

[Robert Sneddon]

Re: LED lighting instead of fluorescent 'haz mat'

I've taken a few prematurely-dead CFL bulbs apart in the interests of SCIENCE!!! and without exception it's the cheapass electronics inside that failed; bulged electrolytic capacitors, bubbly transistors (obviously failed short and/or fried) and smoke-emitting fuses. The tubes themselves are probably fine.

LEDs meant for lighting fixtures have their own problems; the diodes have a positive temperature coefficient so they need control circuitry to prevent thermal runaway since they are run hard to produce lots of light per square millimetre, and heatsinking them is also a good idea to prevent them dying young. The alternative is to simply wire lots and lots of cheap 3mm or 5mm white LEDs together in an array but once you try and light an office to H&S requirements with that kind of setup it becomes more problematical and expensive.

[Nifty]

Re: LED lighting instead of fluorescent 'haz mat'

Halogen lamps can be hazardous to look at if not protected by a UV blocking glass sheet.

[This Side Up]

Re: LED lighting instead of fluorescent 'haz mat'

"The biggest problem with compact fluorescent bulbs is that the need for them to fit standard lampholders, which means that the "replaceable" part contains all the electronics to drive the tube. "

But that was never necessary. I have several lamps and luminaires that use replaceable tubes such as the Thorn 2D (which celebrated its 30th anniversary this year) and Philips PL. In some cases these have adapters which fitted into standard BC lampholders. In the early days CFLs used heavy chokes rather than electronic ballasts but there is no reason why they couldn't have been incorporated into the light fittings. Chokes are vastly more reliable that cheap electronic ballasts which have a habit of going fut long before the tube fails. In fact I've used chokes from old Philips SL lamps to ballast PL lamps in simple lampholders.

What is very sad is that governments have forced people to switch over to compact flourescent lamps instead of waiting a very short time for LED alternatives to become readily available.

[Mike Flugennock]

Re: LED lighting instead of fluorescent 'haz mat'

I can agree that flourescents -- even the modern CFC bulbs designed to replace the old incandescents -- are a royal pain in the ass to deal with. I can still remember my first job out of college, in an office almost entirely lit by flourescents that gave everybody's skin a sickly greenish tinge. I always got a good laugh out of going out for lunch or happy hour at a bar'n'grill nearby and playing a game of picking out the women who tried to fix their makeup under the flourescent lighting in their offices or in the restrooms in our building; invariably, under normal daylight or incendescent light, their faces always had a kind of strange, otherworldly color (snicker).

Still, when recently replacing the flourescent lights in our kitchen at home -- last renovated in 1982 -- I was pleasantly surprised to see how the improvements in flourescent lighting technology resulted in tubes that generated a softer, warmer, more natural and pleasant light.

Btw, excellent article, too; informative and fun reading (yeah, that's right, fun.). I knew that experimental work in LED technology went back a ways, but I didn't realize it went back quite that far, and lately I've been very impressed with the advances in brightness that allow their use in traffic lights, room lighting and car headlights. Still, I'm surprised the article didn't spend much time on the first major emergence of LEDs into the consumer device market, as those of us "of a certain age" will remember those days in the mid '70s when we got our first LED calculators, wristwatches and clock radios. Pretty intense stuff, back then; I remember getting my first wristwatch with an LED dial and thinking "whoa, man, the future's finally here!"

Of course, as the '80s dawned, quartz LCD displays became the Big Thing for wristwatches, but I still preferred LEDs as I'd always found LCD watches a big pain in the ass to read except under perfect light.

[David M]

Re: LED lighting instead of fluorescent 'haz mat'

We've spent thousands of years growing accustomed to the idea that the night is lit by firelight, and tungsten filament lamps approximate the spectrum of firelight rather better than fluorescent or LED lighting.

[Frank Bough]

Re: LED lighting instead of fluorescent 'haz mat'

LED domestic lighting is bloody awful. If they take away my tungsten halogens, I'm installing xenon discharge units.

[Mike Flugennock]

Re: LED lighting instead of fluorescent 'haz mat'

LED domestic lighting is bloody awful. If they take away my tungsten halogens, I'm installing xenon discharge units.

I'm no expert on lighting types, and was never quite able to see the advantage in the halogen-tube lights that have become popular over the past ten or twelve years. They seem a bit brighter, but can't say for sure as I haven't compared them side-by-side with CFC bulbs or traditional tungsten incandescents.

One difference is for sure, though, and that's that halogen bulbs have always been a real pain in the ass to change out. We've lost at least two halogen lamps at our house because we failed the bulb removal "intelligence test" and were left with half a broken halogen bulb in our hands and the other half permanently wedged into the socket.

Also, I'm glad that the CFC bulb manufacturers finally figured out how to make a bulb that looks like a traditional light bulb instead of those ugly-assed "curly" bulbs. The hanging overhead fixtures in our hallways don't enclose the bulbs entirely, so even though the "curly" CFC bulbs fit the sockets, they look ugly as hell sticking out of the fixtures.

[Anonymous Coward]

Re: LED lighting instead of fluorescent 'haz mat'

You really need to take a look at the latest generation of LED bulbs not the older stuff which was indeed crap (and sadly still on sale in many places).

I believe Philips now spend their entire lighting R&D budget on LED technology alone. Or at least thats what someone told me.

[David Given]

Re: LED lighting instead of fluorescent 'haz mat'

My house is lit throughout with GU10 minispot clusters. I originally had halogens --- beautiful light, but 50W each, 150-200W a cluster. And they blew. Frequently. I then replaced them with CFLs. The light was hugely variable and CFLs are simply too big, so GU10 CFLs push the bulb size limits --- I ended up having to saw bits off my light fittings to make them fit. I experimented with some of the early LED clusters and they were an expensive waste of time.

Then I discovered the Philips GU10 LED bulbs. Holy crap they're good.

I haven't tried a side-by-side comparison, but the light seems indistinguishable from my old halogens; they use a single chip, so you get a point source of light, which means that suddenly everything shiny in my house sparkles again (the diffuse CFL light made everything really dull). And they're 4W each. Currently I'm not buying anything else.

They're not cheap, though. At a tenner a piece and three to four bulbs a light fitting, they're quite an investment.

[Anonymous Coward]

Re: LED lighting instead of fluorescent 'haz mat'

I've got 10 of 5W LED "warmwhite" GU10 spotlights in my kitchen. The colour temperature seems fine to me, and it is fair bit brighter than the 10 of 20W halogen spotlights they replaced. ( I vaguely remember the 5W LEDs I bought being rated at something like the light output of 35W Halogens )

LEDs are pretty much "instant-on" unlike the Compact Fluorescent Tube energy saving lights which seem to take a minute or so to warm up ( this is especially noticeable in cold conditions ).

Everyone seems to talk about the energy saving angle of LEDs ( and compact fluorescents ) the extra plus side to this as far as lighting is concerned is the extra lack of heat cooking cables and fittings and therefore a lowering of fire risk. Admittedly if the sparky has picked the correct heat resistant cable, and used nice fire-retardent fittings this shouldn't be a problem. The point is with low-energy-lighting the cables and fittings being "slow-cooked" ( and leading to electrical faults) becomes almost non-existant. As an ex-sparky I've seen plenty of fittings and cables cooked by incandescent lighting.

In the year or so I've had the LED kitchen lighting none have "blown". I was forever replacing the halogen spot lights.

The only downside of the LEDs is their initial cost, however they'll hopefully last quite a few years ( how do they manage to specifiy the high brightness LEDs as having a 10 year lifespan , surely they haven't been around long enough to properly test ? )

Other than LED lighting is brilliant and a bit of a no-brainer, my only advice is that I've found the ones claiming to be "warmwhite" to give off an acceptable colour light, whereas the "daylight" ones were too blue for my liking.

[Nifty]

Re: LED lighting instead of fluorescent 'haz mat'

Yes I like our drinks cabinet to stay illuminated without warming up my stocks of best tipple.

[Paul Vail]

Re: LED lighting instead of fluorescent 'haz mat'

Being scientifically literate in the US (rare animal, I know), I cringe at statements like this. The CFLs contain a very small amount of Hg, like 5 mg or less. If one takes into account the amount of power saved over their 3 year lifespan, and translate that into the amount of coal NOT burned to produce the wasted electricity saved, you'll note the Hg emissions avoided from the coal burning would be far GREATER than the 5 mg released if EVERY CFL bulb was smashed on the ground at its EOL.

Clearly the latter is not going to happen much, and if the bulbs are recycled (accepted for free here in the States by home improvement stores), the Hg release is very, very small. If we add in the overall reduction in Hg to our food sources (less Hg pollution to the Atlantic seaboard fisheries), then our overall Hg exposure continues to diminish even with the widespread adoption of the CFLs.

I don't know where Mr. Hawkins resides, but my understanding is that the UK has a history of relying on coal for some power production as well. Brits, to our uninformed American way of thinking, also likely consume some seafood, and maybe even have conservatives that actually conserve (or know the meaning of the root word - another rare animal in the States).

The total cost of ownership of a CFL is at break-even in 3 months in my area, but the TCO of an LED doesn't reach break-even for most consumers until well over 2 years. I like the 'warm' CFLs personally, and look forward to slightly warmer LEDs as they arrive. I'll begin converting to LED only when the TCO break-even drops below 2 years.

[Pen-y-gors]

Overkill?

"Christmas tree LEDs... can last for up to 100,000 hours each."

Given that Christmas tree lights are only on from Dec 24th to Jan 6th each year, that's 288 hours per year, so they will have an expected lifetime of about 350 years (considerably longer than those old glass baubles!) Are we likely to still be using 13amp plugs at Xmas 2362? This is seriously over-engineered...

[Anonymous Coward]

Re: Overkill?

In my experience the common mode failure of current LED light strings is usually mechanical. The wires tend to be thin gauge and have little strain relief at joints. The average user treats them with no care - especially when untangling them or taking them down.

[Phil O'Sophical]

Re: Overkill?

"Christmas tree lights are only on from Dec 24th to Jan 6th each year"

Traditionalist :)

Sadly these days they often go on around November 25th and stay on until the end of the January sales...

[Anonymous Coward]

Re: Overkill?

I put my Christmas tree up on December 1st, LEDs and all. Dec 24th is way too late!

[Stuart Halliday]

Re: Overkill?

You're forgetting that LEDs start degrading as soon as they are made.

[Michael Kean]

Re: Overkill?

We put ours outside on a tree, and leave them on a timer to run every evening so they double as a path light.

We usually go through a set a year. Since then I've figured out how to make them last much longer. Dip them in wood glue before hanging :) It's the water sitting between the terminals that rusts them away, and the glue seals them.

[Michael Wojcik]

Re: Overkill?

Given that Christmas tree lights are only on from Dec 24th to Jan 6th each year...

Not my Christmas lights. They go on sometime in the first week of December and stay on until I'm damn well ready to take them down. Sometimes that's 6 January, but it needn't be - certainly not before.

Waiting until 24 December to light them up seems rather foolish. What if the sun doesn't come back on the 22nd? That's the whole point of the exercise, isn't it?

(Of course I don't use those LED lamps for my holiday lighting. They're fine for other applications, but I say that if you can't feel the heat from the tree, you're not doing it right.)

[David Given]

Re: Overkill?

http://en.wikipedia.org/wiki/Twelve_Days_of_Christmas

[Andrew Moore]

You could say...

that this technology LED the way for some amazing innovations

[logo obvious]

[Pondule]

Every one already?

I find it hard to believe that "Every traffic signal in the US is now lit by LEDs", anywhere I can verify that from?

[Dave 126]

Re: Every one already?

>anywhere I can verify that from?

If you Google it, the articles that appear in the results would appear to support the assertion, if not address it directly. For example: "Federal transportation officials have been pushing local governments for several years to switch to brighter, more energy-efficient LED traffic signals." -2010,

http://www.springfieldnewssun.com/news/news/local/led-traffic-lights-may-not-be-as-safe-as-expecte-1/nNDTb/

This little article that mentions a real-world issue:

Because LEDs generate so little heat, they can be obscured by packed snow and ice, a problem in northern states. In April of last year, a truck driver ran a red light covered in snow at an intersection in a Chicago suburb and killed a 34-year-old woman turning left and injured four of her passengers.

[DaLo]

Re: Every one already?

Well sometimes a traffic light fails, intersections sometimes are only give way or stop and not lit. If you can't see any light at all any reasonable motorist would assume a traffic light fault and proceed with extreme caution treating it as a give-way, surely?

[Alan Brown]

Re: Every one already?

In colder climates even incandescent bulbs aren't warm enough and enclosure heaters have to be used.

I'm sure the canadians can sell them a few thousand heatpacks.

The problem mentioned isn't new, or exclusive to led signals - and if a signal has no lights showing, common-sense plus road rules worldwide say "approach with extreme caution"

[Anonymous Coward]

Re: Every one already?

The problem mentioned isn't new, or exclusive to led signals - and if a signal has no lights showing, common-sense plus road rules worldwide say "approach with extreme caution"

----

That's great, but only if you see the signal pole and realize this. You may not at night, or perhaps when it is snowing, raining, or foggy.

[Michael Wojcik]

Re: Every one already?

If you Google it, the articles that appear in the results would appear to support the assertion, if not address it directly. For example: "Federal transportation officials have been pushing local governments for several years to switch to brighter, more energy-efficient LED traffic signals." -2010

In what way does that support the assertion that every traffic signal has been switched to LED? The US federal government spent years pushing the metric system, the 55 MPH speed limit, avoiding tobacco products, and a handful of other things that have not found universal acceptance.

The article is flat-out wrong on this point. It was a bizarre claim to make.

[PT]

Re: Every one already?

True, it is not EVERY light. Local governments have enough budget problems already, and can't afford to put out a lot of capital now to save money later. This problem has been ingeniously tackled by the lighting manufacturers, though, who (in my city at least) upgraded many incandescent traffic lights to LED at their own expense in exchange for several years' worth of the money saved on the electricity bill.

[Bryan Hall]

Re: Every one already?

Almost none of the old lights in town are LED based. Only new intersections or those that are changed or expanded use the new technology.

Like home LED bulbs, the new traffic LEDs are very expensive. Sure, you save on electricity, but the equipment costs and labor costs to change them far outweigh that.

[Will Godfrey]

Re: Every one already?

I think you'll find that the LED traffic lights are designed to be directly compatible with the entire lamp module of the old incandescent ones.

[Stoneshop]

Re: @Will Godfrey Every one already?

Err, to an extent. Most conventional-bulbed traffic lights here use the common E27 screw socket with a robust bulb of appropriate wattage, and a mirrored reflector. Some types of replacement LED modules I've seen are just a PCB of the appropriate diameter, filled with 5mm LEDs of the appropriate colour, and mounted directly behind the front glass, so it'd be more than just a simple "swap the bulb".

[Anonymous Coward]

Re: Every one already?

No, but they've changed most over in my little city.* Forget the lower consumption, long life means lower maintenance costs. Manpower and bucket truck rental are both costly. It won't take that long before they're all LED.

Apparently there's one small disadvantage: no waste heat means no ability to melt snow** so if you're wind's blowing the wrong way on a snowy day you might be missing some traffic lights for a while. Unless they put some heating element in there.

Anyway, I've recently bought 4 LED bulbs. 2x540(?) lumens, 2x950 lumens. They're kind of odd, especially the lower lumens ones: they seem dim yet they make everything clearly visible. Personally, I prefer them so I think I'll be switching as my CFLs blow.

* I moved from a UK metropolitan borough (with a town) with a population over 250,000 to a city in the USA with a tad over 15,000.

** Something that has to be considered here.

[heyrick]

Re: Every one already?

"no waste heat means no ability to melt snow**" and "** Something that has to be considered here."

This problem was solved eons ago on the railways. Red, being the most important signal, goes at the bottom. Cannot be obscured by a heap of snow, unless the snow rises to the level of the signal in which case it is unlikely the line will still be in use.

Example photo: http://s3.freefoto.com/images/23/30/23_30_91_web.jpg

[This Side Up]

Re: Every one already?

@Heyrick: "This problem was solved eons ago on the railways. Red, being the most important signal, goes at the bottom. Cannot be obscured by a heap of snow, unless the snow rises to the level of the signal in which case it is unlikely the line will still be in use."

There's one slight problem with doing that. Road vehicle drivers can be red-green colour blind so position is crucial. Train drivers must have good colour vision.

Interestingly LED signals on railways save more cost because three colours can be incorporated into one aspect, much like searchlight signals but without the mechanical filters. Also incandescent lamps were expensive because they had dual filiamnets for redundancy plus the necessary current detection and switchover circuitry. No doubt there is still some proving for LED signals but you don't need to duplicate the LEDs because they're not all going to fail at once.

[Stoneshop]

Re: Every one already?

Road vehicle drivers can be red-green colour blind so position is crucial.

Or pattern, although that would need a new traffic code to go with the differently-placed lights. Like a red X for stop, a yellow - for impending stop, and a green O for go.

[Anonymous Coward]

@heyrick

This problem was solved eons ago on the railways. Red, being the most important signal, goes at the bottom. Cannot be obscured by a heap of snow, unless the snow rises to the level of the signal in which case it is unlikely the line will still be in use.

----

Er...what? Perhaps I'm missing something, but I fail to see how having the red signal on the bottom makes any difference whatsoever to whether it can be obscured by snow. Can you explain why this makes a difference on a railroad?

The issues noted in the US are due to wind blown snow freezing onto the face of the signal. With incandescent bulbs they had enough waste heat to keep the surface of the glass above freezing (except maybe in places like Nome) so this never happened. With the more efficient LEDs, a heavy wet windblown snow can stick to the surface and prevent you from seeing the signal at all, regardless of what color it is or whether red is at the top, bottom or middle.

[Stoneshop]

Re: @heyrick

Perhaps I'm missing something, but I fail to see how having the red signal on the bottom makes any difference whatsoever to whether it can be obscured by snow.

Signals, and traffic lights, have these shadow shields that (try to) keep direct sunlight off the glass. Snow collects on them, and obscures the light above.

[heyrick]

Re: @heyrick

@ Doug S: "Perhaps I'm missing something, but I fail to see how having the red signal on the bottom makes any difference whatsoever to whether it can be obscured by snow."

Fow what it is worth... here's why red comes at the bottom (as previously noted by a commentor, I'm just giving you a pretty picture to look at <g>):

http://www.southernelectric.org.uk/features/galleries/snow2010/img/csm450028winchfield090110.jpg

[kain preacher]

Re: Every one already?

It's not true. Looks out side and sees a non LED signal lights.

[Anonymous Coward]

Re: Every one already?

Even here in my Indian home city, the traffic signals are, I think, LED. One sad thing: the old ones used to have the word RELAX on the red light: they don't do that now, so nobody does.

On the colour temperature issue, I just replaced most of the cool white fluorescent tubes in my house with warm white. I find it much more restful and soothing ...but is it natural? It is certainly nothing like the hard tropical sunshine outside, so no, in that sense it is not, but it makes my house feel more like a home and less like an office.

[Paul Vail]

Re: Every one already?

I live in Raleigh, NC, USA. There are still signals that have not been converted, but my unscientific survey would say at least 90% of the lights I drive by have been converted. An article in the local rag here years back ran the power consumption numbers, and noted that the (then) very pricey bulbs would pay for themselves in electrical savings in well under a year. Naturally, our taxes were not adjusted downward a year on, so either the cost savings was not realized, or we have politicians in our midst. Me fears the latter.

So no, the claim of the author was inaccurate, but every time a bulb blows in a signal there is one less tungsten traffic light. BTW -- we are somewhat slow to adopt new technology in the South. A generation has to die out before we move ahead one step.

[frank ly]

Semiconductor diodes always confuse people

"...adding a battery with its positive end connected to the free electron 'n' side of the diode, and the negative end connected to the extra holes 'p' side, things change. The 'n' side electrons are attracted to the positive electrode, and the 'p' side holes are attracted to the negative electrode."

That is a reverse biased diode; no current flows and the depletion zone increases in thickness. As you say :

"No current flows because both the electrons and the holes are moving away from each other. But the depletion zone increases, ......"

But then ...

".... and the interaction between the electrons and the holes releases energy in the form of photons - which generate light."

No. There is no interaction because the electrons and holes move away from each other to opposite ends of the diode, like shy boys and girls at a dance.

It is when the diode is forward biased, with the battery anode connected to the 'p' side and the battery cathode connected to the 'n' side that current flows. Electrons are injected into the 'n' material and flow towards the depletion zone, thus reducing its thickness; 'holes' are effectively created in the 'p' side and flow towards the depletion zone (reducing its thickness to zero), where they combine with the electrons - the resulting energy being converted (partly) to light.

Wikipedia has a good diagram of this:

http://en.wikipedia.org/wiki/File:PnJunction-LED-E.svg

[diodesign]

Re: Semiconductor diodes always confuse people

Whoops. The article's Semiconductor Physics 101 has been tweaked. Thanks for the feedback.

C.

[Neil Woolford]

Reverse biased diodes don't pass (significant) current.

So where is the energy coming from to create the light?

Every time one has lit up for me, it's been forward biased, with a ballast resistor or other arrangement to ensure a sustainable current level and avoid self-destruction.

As I've been tinkering with them since their infancy I think I've got them the right way round.

[Phil the Geek]

Re: Reverse biased diodes don't pass (significant) current.

Yep, forward-biased makes them glow, in simple applications you use a series resistor to set the current/brightness to the desired level. The resistor often consumes more energy than the LED, hence the use of more sophisticated controllers in lighting applications.

I'm surprised no-one has mentioned the Q-word - Quantum. LEDs are one of the most visible (ha!) demonstrations of quantum physics. The real magic is when the recombination takes place; electrons drop to a lower energy level, emitting the excess energy as a photon (a particle of light). The frequency or colour of light is determined by the energy of its photons, and the exotic materials in LEDs are chosen to get the right "energy gap" to get the required colour.

The macro world we sense has continuously-variable energy levels (e.g. the orbit of a planet, the speed of a car, etc) but at the atomic level only certain discrete energy levels are possible, hence the emission of a very defined quanta of light energy from recombination, and therefore the tight spectral purity of LEDs.

[Lunatik]

OLED energy efficiency? Hmmm...

"Our monitors, televisions, laptops, smartphones and tablets are now capable of delivering a picture quality that makes us grin without forcing us to recharge often enough to make us groan."

My experience with OLED screens is that they are no less energy-hungry* than backlit LCD screens, so while they do have many benefits, energy efficiency is not really one of them at this time. Plus, the well documented issues with producing durable and cost-effective OLED screens of larger sizes pretty much means OLED "monitors, televisions & laptops" remain a possibility for the future, rather a reality today.

* OK, I know that in lab conditions that, compared to a similar LCD, the OLED will consume less energy showing a dark image and more showing a light one, but in general this usage evens out on average. I dare say that with an optimised (i.e. dark) UI and apps, OLED could be made to go much further.

[Anonymous Coward]

Bored of Blue LED now!

Just because Blue was difficult until 10-15 years ago, it's been "trendy" for some time now to light things up blue.

It's horrible, it hurts my eyes, it's unnatural, it doesn't look nice, it's not trendy any more, PLEASE STOP IT, world!

That is all.

[M Gale]

Re: Bored of Blue LED now!

In the 70s and 80s, high technology came with a wooden veneer and lots of lovely knobs, flick switches and dials.

In the 90s, it was CHROME, CHROME EVERYWHERE.

Now, high technology glows blue.

It's just one of those things. Next it'll be touch screens on everything.

[igottheflag]

Re: Bored of Blue LED now!

I have two words for you.. "black ash"..

[Stoneshop]

Re: Bored of Blue LED now!

In the 70s and 80s, high technology came with a wooden veneer

Indeed. I do miss those rosewood- and palissander-sided mainframes of yore. Painted sheetmetal is so crude by comparison.

[Tom 35]

Painted sheetmetal is so crude by comparison.

Now it's black plastic with small off-white text that can't be read from more then 6" away.

[Mike Flugennock]

Re: Bored of Blue LED now!

In the 70s and 80s, high technology came with a wooden veneer and lots of lovely knobs, flick switches and dials.

In the 90s, it was CHROME, CHROME EVERYWHERE...

Eeehhhh, maybe, maybe not, depending on where you lived, I guess.

For me, the late '60s/early '70s had the cool wooden veneer cases with lots of backlit FM dials, and those edge-lit electroluminescent signal/VU meters, and yeah, more knobs and flip switches than you could shake a stick at.

The mid '70s came along and all that stuff turned into red LEDs, except perhaps for VU meters, most of which still used needles. Still lots of fake wood until the late '70s and early '80s, when we suddenly started seeing all the chrome and fake brushed aluminum we could take. The early '80s also gave us really cool electroluminescent VU meters along with LEDs everywhere in our tape decks -- or, as my sound geek pals called it, "Tokyo By Night". (Interestingly, I don't remember a whole lot of LCD displays on stereos back then)

In the '90s every display in every sound-system component I saw turned into blue and amber LEDs, even the VU meters, and with lots of those little pushy-touch switches -- and lots and lots of black. Cases, knobs, display bezels, everything. The sound components on the table next to me -- tuner, amp, CD player -- were bought as a set around 1991 or '92, and it's just a big-assed stack of black. The tape deck was bought in the mid/late '90s and it, too, is a big ol' black slab.

...It's just one of those things. Next it'll be touch screens on everything...

Yeah, even touch screens on things which aren't really suited for touch screens, sadly. Still, I have seen some consumer electronics and appliances that have benefited from having little EL screens with little bare-bones GUIs running on them. We just got a new printer/scanner/copier combo at our house, and it has a little screen on it about the size of a video iPod screen with four or five buttons around it that let you click and scroll through the menus. Really well done, actually.

Actually -- granted, it's a long shot and rather silly -- I'm hoping the next trend in stereo components is brushed aluminum and wood cases with little nixie-tube displays for the tuners. I know you really need LEDs or LCDs to build a proper handheld calculator, but nixies still have a slight edge in "coolness".

[Phil O'Sophical]

Re: Bored of Blue LED now!

It's not "Bored of" it's "Bored WITH".

I hate "Bored of". It's horrible, it hurts my eyes, it's unnatural, it doesn't look nice, it's not trendy any more, PLEASE STOP IT, world!

That is all.

[sam bo]

Re: Bored of Blue LED now!

It's not "Bored of" it's "Bored WITH".

I hate "Bored of". It's horrible, it hurts my eyes, it's unnatural, it doesn't look nice, it's not trendy any more, PLEASE STOP IT, world!

That is all.

it is right up there with "try and do it" which to my eye reads as "you should try to do it AND do it "

what is wrong with " try TO do it " ?

[Anonymous Coward]

Re: Bored of Blue LED now!

Green is the eye's most sensitive part of the spectrum. Blue is one of its much less sensitive areas. However for most people there seems to be a psychological attraction to "pretty electric blue" - as every Igor knows. That makes some traditional sources dangerous attractions because of their UV content (not standard blue LEDs)

[Mike Flugennock]

Re: Bored of Blue LED now!

...However for most people there seems to be a psychological attraction to "pretty electric blue" - as every Igor knows...

Huh, never thought of that. Yeah, blue does look kinda cool, but I've never been that into it one way or the other. It could be a generational thing; the first devices I owned with LEDs in them in the mid '70s -- my first digital clock radio, my first digital watch, my first handheld calculator -- all had red ones, and so I came to associate that authoritative red LED glow with "high-tech future".

Of course, the famous Apollo Guidance Computer was already bucking the trend with a green display.

[Anonymous Coward]

Re: Bored of Blue LED now!

A neighbour has what appears to be a matrix of powerful blue LEDs (or lasers) in his back garden. Presumably an intruder detection system. Even an edge scatter seen through a house window at 30 metres plus feels painful.

Anyone any idea what they might be? No point asking the neighbour - he seems to treat such installations as his divine right.

[Haku]

@AC 12:27

I doubt the string of blue LEDs your neighbour has is anything to do with the workings of a security system - other than a visual warning - because PIR sensors rely only on heat and 'night vision' security cameras usually rely on IR light.

Much like this laser scanning security device someone developed which does absolutely nothing other than provide a 'light show' to warn potential burglars that there (probably) is a high tech security system in the premesis - https://www.youtube.com/watch?v=GnH95uzQPOo

[Dave 126]

Blue LEDs as ornaments

And Jeebus, I walked my dog past some houses the other day, and couldn't help but notice that people had decorated their indoor Christmas trees with blue LEDs. I can't stand the things, but it seems some people like them. These weren't the sort of houses that are enthusiastically covered in plastic reindeer and inflatable snowmen, either.

Bad design: Yesterday I bought a car cigarette-lighter >USB power adaptor from a garage... it was fitted with a blue power indicator that was so bright it would distract any driver. Not good. Still, it was easily fixed with the Duck-tape that is kept in the car.

[Robert E A Harvey]

Duck tape

Since we have so many pedants around, I am surprised tnat no-one has pointed out that Duck Tape is a brand of duct tape. In the Uk we call it 'Gaffer' tape, after the head electrician in theatres, renowned for using it to solve all problems!

[Anonymous Coward]

Re: Duck tape

Indeed, branded Duck tape's the best. The cheaper chinese copies are rubbish...

[Cupboard]

Re: Duck tape

I'd buy something from Advance Tapes or Le Mark over Duck any day.

[Stoneshop]

Re: Duck tape

Indeed, branded Duck tape's the best.

Well, if you ignore Nishiban.

[Tom 35]

Re: Duck tape

Proper 'Gaffer' tape is different them Duck/Duct tape (and much more expensive).

[Hayden Clark]

Re: Duck tape

Sigh, here we go again. Even the Wikipedia article gets all out-of-shape over "Duck" and "duct" tape, while correctly describing the function of each.

The sticky, hand tearable stuff that you repair the world with is Duck tape. This follows on from the military stuff used to hold ammo boxes shut and keep the wet out.

If you used Duck tape on a duct, it would quickly dry and crack, especially if the duct carries warm air. Duct tape does not have the awesome properties demonstrated on Mythbusters. It does, however, have adhesive that continues to work at higher temperatures, and is resistant to cracking. Some varieties incorporate a foil layer to improve airtightness.

[Stuart Castle]

Re: @AC 12:27

Indeed. Where I work, there was classified technology on the premises. The whole building was protected (during that period) by the Military police (although we are not a military organisation) and a security system using lasers. The only visible sign of the security system were 8 foot tall smoked glass towers placed at regular intervals throughout the grounds, along with a *lot* of security cameras.

[Michael Dunn]

Re: @AC 12:27

I bet eight-foot tall military policemen would also have been a deterrent to any potential intruders!

[Vic]

Re: @AC 12:27

> to warn potential burglars that there (probably) is a high tech security system in the premesis

Or, more likely, to inform burglars that there probably *isn't* a high tech security system on the premises...

Vic.

[heyrick]

Re: Bored of Blue LED now!

"A neighbour has what appears to be a matrix of powerful blue LEDs (or lasers) in his back garden. Presumably an intruder detection system."

Um... FAIL? Surely the point of sensors is that they see you before you see them - hence the bank heists in movies using special vision goggles and spray-can smoke, etc... I mean, what good is pointing out the security system? That'll just tell potential burglars where to avoid - like land mines with little pink flags on top...

BTW, FWIW, I like blue LEDs.

[Anonymous Coward]

Re: Bored of Blue LED now!

Nope.

I use blue for power/access indication and background lighting (when not using white, that is). Red is alarm, green is OK, blue is live.

[John Bailey]

Re: Bored of Blue LED now!

Anything with blue LEDs is by definition cool. You obviously just need more of them.

[Alan Brown]

Re: Bored of Blue LED now!

Blue light in a bedroom is a fast way of getting a rotten night's sleep. That was fairly well known a long time before blue leds came in the scene.

Personally I hate excess use of blue because the it's harder to focus on (the eye is optimised for green-red) and tiring after a while.

[Mage]

Home & Work Light?

It's rubbish for those as the spectrum is too poor. Missing colours. It's not even as good as CFL in which the phosphors work better. CFL even is poorer than Halogen for colour rendition.

[Nick Collingridge]

Re: Home & Work Light?

LEDs work absolutely fine for us - we have replaced nearly all lights in the house (apart from a few remaining CFLs) with LED and the light quality is wonderful in my view. I have used the "Warm white" LEDs (around 3000k nominally) and the colour rendering is very much better than CFLs and about the same as halogen - the problem with CFLs always used to be certain foods (such as red meat) just appeared the wrong colour, but this problem does not occur with LEDs.

[the spectacularly refined chap]

Re: Home & Work Light?

I agree with Mage here. Ultimately there is no such thing as a true "white" LED - they are essentially integrated green, red and blue units in the proper balance to approximate white light to a human eye. However, that lack of continuous spectrum does cause subtle colour issues at times - I think I've commented here before that it is virtually impossible to distinguish brown and violet resistor colour bands under LED lights. It only takes one or two expensive, time consuming mistakes caused by that kind of issue before you are left vowing never to trust LED lighting again.

[Stoneshop]

Re: Home & Work Light?

they are essentially integrated green, red and blue units in the proper balance to approximate white light to a human eye.

They're not. "White" LEDs are essentially UV or near-UV (single-colour) LEDs with fluorescent coating. Some coating mixtures are better than others at providing a not-awfully-gappy spectrum, but it's still discontinuous, like, well, fluorescents. Another issue is that the coating degrades with use, although it tends to keep up well beyond the life that most incandescents have anyway.

[Mage]

Re: Home & Work Light?

"Colour rendering is very much better than CFLs and about the same as halogen"

Nothing like. LEDs have gaps in the spectrum. You are confusing "Colour Temperature" or how Neutral the colour appears looking AT it or neutral surfaces to the accuracy of colours seen with the light reflected from objects.

Certain shades of Cyan will go green or blue. Other colours will go "muddy" or even grey.

CFLs and Florescent tubes have spikes and some gaps, but due to the direct plasma and mix of UVA and UVB wavelengths a mix of phosphors can give much better light than the Blue/Violet/Near UV of an LED. White LEDs don't exist, they use phosphors. R G B LEDS can "mix" to give illusion of almost any colour, but are the very worst illumination source as it's near monochromatic Red, Green and Blue. Coloured objects will appear the wrong colour and it's possible to have a brightly coloured object appear dark grey or a darker spurious colour under RGB light than under CFL or even phosphor based White LED. It will be most natural in overcast sky mid daylight and next most natural (but orange enhanced) under Halogen. Only Halogen and Tungsten can be colour balanced later in Photo Editing. With RGB or White LED the colour information isn't in the photo or video, it's lost.

Cameras use three or more broad overlapping responses to generate the RGB data for later colour image (which can then use monochromatic RGB). But you need broad spectrum lighting with no gaps to create the viewing illusion accurately.

[Frank Bough]

Re: Home & Work Light?

Halogen is excellent for colour rendition - only xenon is better. Turn up your wattage.

[Mage]

LED is fantastic

But one thermionic tech refuses to die, the VFD used in Media players, Set-boxes, car dash boards and Tills/POS. Invented as Computer Indicator in late 1950s, Japanese 7 segment displays in 1960s calculators (one digit per valve) and pocket calculators in 1970s (single tube with all digits)

1952 Triode magic eye, DM70 & DM71

1959 VFD, works on 9V HT and with TTL drive DM160

The russian iv-15 a DM160 clone

Some history of indicators including LEDs and a Timeline

Nortake/Itron, Futuba, Samsung still make them Some nice Russian NOS and Asian ebay types here

[Anonymous Coward]

Re: LED is fantastic

Where would my Hammond be without its EL34s? Mind you they do glow blue a bit when overloaded...

[Will Godfrey]

Re: LED is fantastic

Sharply defined bright blue is fine (provided the anodes aren't red-plating). It's the pale diffused blue that's a problem - means the valves are going 'soft'.

OK, I'll crawl back to my rocking chair now.

[Tom 7]

Re: LED is fantastic

Sharply defined blue is NOT fine. Chromatic aberration means that for many - especially the short sighted blue will result in massive blurring.

If you had laser treatment a few years ago its a fucking nightmare.

[Stoneshop]

Re: @Tom 7 LED is fantastic

Sharply defined blue is NOT fine.

That bit was not about light sources, it was about amplifier valves. Which are not primarily meant as illumination.

[circusmole]

...and they last for XXX years...

What a lot of baloney. I decided to replace eight downlighters in my kitchen with eight 4W LEDs. I did this about 14 months ago and I went for the quality end of the LED market - not eBay rip-offs. I guess, on average, these lights are on 10 hours per day.

In the last 14 months 3 of these LED lamps have failed :-)

[El Zed]

Re: ...and they last for XXX years...

Ah, despite going for the 'quality' end, you still fell for the marketing.

Just because the LEDs themselves may last, yea unto the very end of time itself (or 50,000 hours or so - whatever comes first), doesn't mean that any device built using them will last till beyond the warranty/guarantee/week/first real power surge after you purchase them.

A bulb that lasts for years?, FSM what fools these mortals be! (besides, what lamp manufacturers in their right minds would so willingly cut their own throats?)

Remember, the same people used to say that CFLs would last for years too...(admittedly, I've one which is now over 15 months old, still, I think I'm averaging 7-9 months out of them - this may be a local electricity supply 'quality' issue though).

[John Bailey]

Re: ...and they last for XXX years...

CFLs regularly last years for me. But then I have a nice stable power supply, and they tend to be on or off for long periods. Constant switching tends to be not so good for them, and obviously they do not react well to dimming.

My kitchen fluorescent tubes have lasted 5+ years each.

I have 3 incandescent bulbs left in my home. All in places where they will be on for minutes tops.

So the companies that cut their throats by selling long lasting light sources seem to be quite common.

[Bryan Hall]

Re: ...and they last for XXX years...

I agree.

The LEDs themselves may still be good, but the crap electrolytic caps supporting them love to dry out an fail. Good luck getting them replaced under warranty.

On the other hand, most 20,000 hour incandescent bulbs generally make it to their designed lifetime - thanks to KISS technology, and then cost next to nothing to replace when they do.

Look, I am for LED and other new technologies. But only if they are good looking and truly economical to use and are not forced onto me by a tyrannical Govt.

[Richard Cartledge]

Re: ...and they last for XXX years...

I agree, when they are driven hard enough to produce task light, they often blow or flicker after a few months.

[Vic]

Re: ...and they last for XXX years...

> I decided to replace eight downlighters in my kitchen with eight 4W LEDs.

I did something similar.

> I went for the quality end of the LED market - not eBay rip-offs

I went for the cheapie eBay crap. I paid about £3 each.

> In the last 14 months 3 of these LED lamps have failed :-)

In the 2 years or so I've had them, none of mine have failed[1].

Vic.

[1] Not *strictly * true; the glue holding the LED board into the housing came apart on one of them. I glued it back in place and it's been fine...

[James Hughes 1]

Re: ...and they last for XXX years...

Odd, my house is mostly CFL with some GU10 incandescent and some GU10 LED (cheap ones)

The only CFL that is iffy was in the house when we moved in 5 years ago - takes a while to get going. All the rest have been working fine since we arrived. The LED GU10's have never failed, but the incandescent ones are always popping.

We also have had (in the past) persistent power cuts and brownouts during that 5 years.

So my experience is that CFL and LED last longer than the incandescent equivalents.

[Richard Cartledge]

One by one, we are replacing our domestic CFLs (Compact Fluorescent Lights) with SMD (surface mount diode) 'corn cobs'. The latest SENCART branded ones we have from dx.com are superb, even better CRI(colour rendering index) and cosiness than old tungsten bulbs and they are full brightness instantly unlike most CFLs.

I don't know why they still make CFL, they should be phased out and replaced with SMDs so they can be made cheaper in greater volumes.

[Tom 7]

so they can be made cheaper in greater volumes...

or some submarine patent will surface just as they make a de-facto monopoly and we will all be screwed.

or bayoneted.

[Anonymous Coward]

Re: screwed or bayoneted

Good grief, I had to think about that!

[Hungry Sean]

better CRI than tungsten??

With all due respect, what *are* you smoking? CRI is a measure of color similarity to a black body (aka incandescent) source at the same color temperature. By definition, you can't beat an incandescent light on that metric. It is possible, particularly with the three component LED lights (RGB as opposed to blue + phosphor) or the triphosphor fluorescents to get greater color saturation from an artificial source, but that's certainly not the same as from color fidelity.

[Stoneshop]

Re: better CRI than tungsten??

By definition, you can't beat an incandescent light on that metric

Well, actually you can, as a glowing filament is not quite a black-body radiator of the same temperature, but for all in tents and porpoises, it's close enough to moot the difference.

[Hungry Sean]

Re: better CRI than tungsten??

well, CRI for a tungsten filament bulb is rated at 100 (I suppose that they round to nearest integer). But yes, you're right. Think you picked the wrong icon though-- here, let me fix that for you :-).

and for those of you keeping score, daylight is even further from a perfect black body due to the effects of filtering through the earth's atmosphere, so CRI should be slightly worse than tungsten (omg wtf bbq).

[Fred Flintstone]

I don't know why they still make CFL, they should be phased out and replaced with SMDs so they can be made cheaper in greater volumes.

Actually, I can't find it right now, but CFLs are apparently being silently phased out because they are (somewhat ironically) an environmental disposal nightmare waiting to happen - the stuff inside the glass tubes is not good landfill material.

The volume will come. I can already see IKEA come up with far more sensible prices - cheap enough to start replacement programs. And LEDs are *so* much more flexible in deployment..

[CCCP]

So that's what I have....

@Richard Cartledge

Thanks for letting me know that's that my LEDs are. Although flat in my case, 'corn cobs' is a perfect way of describing them.

I bought them on recommendation 2+ years ago in an actual shop(!). Expensive but, out of 9, none have failed or appreciably dimmed. They're heavy GU10 replacements, suggesting they have good heat sinks.

Sadly, they are one of those rare, good, Chinese imports with no particular brand name, so I can't tell you what they are.

[Anonymous Coward]

Re. bad caps (TM)

Yes, same problem here. 3 dud lamps, 2 of them had bad capacitors.

One turned on and off when hot, never did find out why but suspect some other component failed on them as the LEDs look fine and work correctly on a DC current limited supply.

Shame, as they are actually quite nice lamps with no significant heating in use and the light quality is good.

If you still have yours unscrew the end and the PCB usually falls out and can be autopsied.

Currently working on an improved bike light using the three "dead" lamps to make a cluster of variable brightness lights that also serve as indicators.

[Hungry Sean]

leds for home/office lighting

I'm not convinced they are there yet-- manufacturing variation in chromaticity is very high (that is, three or four units from the same manufacturer of the same nominal color temperature will be visibly different). Producing a pleasant warm light (<4000K) is still a big challenge, and as someone above mentioned, that is a must for US/EU markets.

Fluorescent lighting, which is obviously much more mature, has solved these problems and you can get some very nice CFLs now that can be dimmed or provide instant on as well as high CRI. Factoring in the difference in unit cost vs efficiency (a single LED replacement bulb here in the states was about $50 last I checked) and the value proposition just doesn't make sense. I'm sure that LED lighting will improve over time, and there is a lot of potential, but I'm not about to retrofit my home.

[M Gale]

Re: leds for home/office lighting

Producing a pleasant warm light (<4000K) is still a big challenge, and as someone above mentioned, that is a must for US/EU markets.

Perhaps, but there's plenty of manufacturers rising to the challenge successfully. It's actually hard to find a "daylight" LED bulb around here, with most of them being 2300-2700K. Yes, there is always the Internet, but that's not "round here".

Gotta wonder what anybody snooping at my bank records must think when they find purchases for 30 watt CFL grow-lamps with a 6500-7000K temperature. It's probably not "well he doesn't like yellow then".

[Stoneshop]

Re: leds for home/office lighting

(a single LED replacement bulb here in the states was about $50 last I checked)

Even brand-name LED bulbs (Philips, Osram) here are nearly an order of magnitude cheaper, and you can get off-brand bulbs for not much more than CFL prices (about 2..3Euros).. Either you've checked the wrong places, or someone's fleecing you guys *HARD*.

[Hungry Sean]

Re: leds for home/office lighting

just double checked with home depot's website and my memory isn't too far off -- they range between 25-45 usd. I suspect that this is a case of Europe being ahead of the states-- both Osram and Philips are European companies. Here in the states, we're still migrating to CFLs, so I dunno. Maybe Osram/Philips and co are using the states to dump their CFLs as they phase them out and phase in LED tech.

On the other hand, here in the heart of silicon valley, we still haven't figured out the principle of grounding wires (most residences don't have them due to a combination of age of construction and some incredibly backwards tax laws), so who knows. I

[Yet Another Anonymous coward]

Bootnote

Here in Canada it's estimated that mandating CFLs will add around 500,000 tons of CO2/year to the atmopshere

The electricity in Quebec and BC is hydro but without the extra heating effect of all those 100W electric heaters the thermostats click in and burn more natural gas or oil

[Stuart Halliday]

LED lighting has other properties that are not so obvious.

They can be made in any size and shape. No more are designers limited in trying to hide that old bulb shape with a shade.

The light given off is polarized so the reflected light off objects looks sharoer and travels through fog further than normal bulbs. So in real world tests, places look dirtier and sharper. Wallpaper and interior designers will have a field day making new designs for us to buy!

Being able to dialup a new colour every day from my LED lamp will open up new markets for paint companies as they make new dyes to reflect polarized light in interesting ways.

:)

[Callum]

mountain bike lamps

CREE XPG etc LEDs have revolutionised night mountain biking, with 1500+ lumen output and long burn times. One of the big problems though is that using them in a snow storm is headache inducing - possibly why they are not used for car main headlights.

[Kubla Cant]

Re: mountain bike lamps

Not just mountain bikes.

A fairly early application of LEDs was rear lights for pedal cycles. Instead of a horrible dim, bulky thing that ate batteries, we got a brilliant light that flashed. So cheap and lightweight that you can have several on each bike. The batteries last so long that many cyclists now use lights in the daytime as well as night.

It took a frustratingly long time for a good, white headlamp to become available, and the early ones weren't very bright. But now you can get a lamp that gives a dazzlingly bright beam and good battery life. The only complaint I've heard is that the beam is less coherent than an incandescent lamp.

[Alan Brown]

Re: mountain bike lamps

"But now you can get a lamp that gives a dazzlingly bright beam and good battery life. The only complaint I've heard is that the beam is less coherent than an incandescent lamp."

You'd get plenty of complaints if you were listening to motorists coming inthe opposite direction, especially on country lanes.

I've had to stop a few times and wait for my eyes to readjust after being blinded by groups of cyclists. There are legal limits on lamp height, light output and beam shape for a reason - and they apply as much to bicycles as much as cars and motorcycles, according to the DfT. While policing is only just catching up to the fact that bike lights can be dangerously bright nowadays, it's only a matter of time before prosecutions start.

The worst offenders use frame and head-mounted lights. It's far worse being hit full in the face by a light 6 feet off the ground than one at handlebar height.

[The_H]

Call me cynical, but no-one is going to release a commercial lamp - of any variety - that doesn't need regularly replacing. Our office is lit by not-at-all-cheap LED fittings and the lamp failure rate is not much better than standard fluorescents.

[illiad]

I think you are mistaken... have a look at the stores, and see how many sell what type of bulb... due to demand, they have to stock many varieties, even the small halogens, for those with 'designer lighting' homes... you will find that many people think first of the cost, then design (usually constrained by the thoughts of the designer/builder of their new home!! :( )

[Old Handle]

Christmas Lights vs. Room Lighting

LED Christmas Lights are EVIL spawn of Cthulhu and must DIE. They look like twisted eldritch simulacra of real Christmas lights. The colors are completely unnatural, they flicker in the corner of your eye and they are not the least be cheery.

On the other hand, I've got an LED light "bulb" in my bedroom now which is surprisingly good. It's probably not super efficient, because it works by shining several blue or possibly UV LEDs on a fluorescent plastic globe, but to my eyes it is indistinguishable from incandescent.

[illiad]

Re: Christmas Lights vs. Room Lighting

LOL :D you havent been spending enough on your decs then!!!!

[Anonymous Coward]

Re: Christmas Lights vs. Room Lighting

Easy solution: let's just do away with Christmas! As soon as possible.

Bah! Humbug!

[Allan George Dyer]

I'm waiting for the black LED

Black is cool, black is the future. "Every time I press this black button on a black background, a black light lights up black to tell me I've done it!" (Thanks, Douglas)

[Stoneshop]

Re: I'm waiting for the black LED

No problem. Just apply the voltage from four or five D cells, a 12V wallwart or in the most stubborn cases, a car battery straight to the LED pins (positive to anode). Caution: may cause SEDs (Smoke Emitting Diodes), small pieces of plastic flying off, unintended blackness elsewhere, unintended malfunction elsewhere, lack of device feedback, itchy rashes, full body hair loss, projectile vomiting, gigantic eyeball, the condition known as 'hot dog fingers,' children born with the head of a golden retriever, seeing the dead, bone liquification, possession by the Prince of Darkness, tail growth, elderly pregnancy, back pain and a runny nose.

[heyrick]

Re: I'm waiting for the black LED

Dammit, it's the runny nose that's the deal-breaker for me...

[harmjschoonhoven]

Re: I'm waiting for the black LED

The black LED does not exist as it requires a radiating body at 0 K, which is impossible.

[Stoneshop]

"Liquid Crystal Diode (LCD)"

FAIL.

LCD stands for Liquid Crystal Display, and there's nothing diode-y about them: it's a liquid crystal that changes the polarisation of light passing through it when they're subjected to an electric field through two electrodes. That field has to be flipped periodically to keep up the crystal alignment,

With this, and the total fail of understanding semiconductors, I wonder what the author's qualifications are for writing such an article.

[Mikel]

Building thermals

A lot of buildings now use heat pumps. These are more efficient at warming buildings than incandescent. But they don't work as well in really cold places.

[madestjohn]

As someone who works professionally (gaffer, film industry) with all different forms of lighting,( led, tungsten incadescent, hmi, flourencent, carbon arc, hell i even got the philips prototype oled luminblades) let me say this, they all suck but for different reasons.

Led have plenty of suck ... First led droop, ( which last time i looked no one had really figured out) the lost of effeciency as power levels increase mean there's a serious limit on how brite a single source led can be so you are required to stack them, basically stick a bunch together to make the whole brighter this causes tons of issues not only optically, rather than having a basic single source which you can then optically focus you are limited to a multisource array with muliple shadows, rainbowing, and plenty of other artifacts. This also it a major heat issue, while a single led is much more efficent than a incandescent per watt it is also much much smaller so has less surface area to disperse heat. When you start stacking dozens of them closely together this becomes a major problem. I always find it amusing how shocked people are when they see the massive heat sinks on the back of large professional led arrays.

There are even household bulb designs that are using liquid silicon to help deal with this issue.

When you combine this with the circuitry required to run them and the fact that most arrays are built as a single unit, so when you lose indivisual leds you can't replace them and eventually need to replace the entire unit, so while a 50,000 average hour bulb life sounds great when you realise what your really saying is a 50,000 average unit life not so good. I have units on my truck that i use almost daily that are almost as old as i am, i can be pretty certain that none of the led units i have will be functional a decade from now.

Then there is colour, and from reading the above comments almost everyone here need to brush up on their colour theory, lets just say like all non black body emiters leds are a nightmare when it comes to colour. Yes there is no such colour as white but the one thing white is is full spectrum. Led, fluorescents, hmi and other non fullspectrum all have had allot of effort and investment in getting arround the fact that they are naturally missing chunks of the spectrum and most are able to get thier cri (colour rendering index) up to the low 90 in optimum conditions, the thing is optimum conditions don't tend to stay optimum, and when you have a bunch of mixed sources and they all start going off optimum in thier own way on set, well, this is why gaffers tend to nervous wrecks.

Yes led can as a side benifit of having to be stacked have the option of rgb mixing, or for the better arrays rgbcow, but while this may work well as a wash across the back wall the human eye is very atuned to skin tone, especially green and red as its important evolutionarily i suppose to know when a fellow tribe member is about to attack or puke on you, and the limited bandwidth options with the indivusual elements of an rgbled has meant allot of overselling of the usefullness of this option.

Lets not even talk about the nightmares that can happen when dealing with frequency, most led dim by changing freq of on/off cycle rather than brightness which when mixed with the fixed freq. of camera, or the eye of a person who has trained himself to notice freq, can produce incrediblely anoying artifacts.

So yes, .. Led is an useful option, but does not in anyway replace the need and function of incadescent glowing tungsten wires of the basic classic bulb, not in quality or high output, and while led will always have function where it makes the most sense, and we have seen allot of improvements lately as the tech has matured, as we have recently with the more mature fluorescent - the new t5 and t4s are very impressive, it is not the best option in all situations and i actually am very willing to bet that it will not be the unit thats lighting your homes twenty years from now.

Now ... Radio activated plasma bulbs ... That I'm excited about.

[Hungry Sean]

love this about the reg-- there is almost always at least one commentator who really knows their shit, regardless of the subject. Think the posts on this article have been far better than the article itself, and this one does a great job of cutting through the fluff. Happy new year's. beer since there's no champagne icon.

[Frank Bough]

Pure xenon discharge lamps are the only proper non-tungsten light source for imaging, though I metal halide lamps may become practical broadband light sources if development continues along the current trajectory.

[Fred Flintstone]

Quite simply, thanks for that.

I know sod all about light *sources*, but I know a lot about colour. For no sensible reason whatsoever I'm one of these rare people that can see colour differences close to 3 MacAdam, and I have worked at one time as a professional colour recipe develope before I got distracted by IT. In short, I see colour differences very clearly which is a fantastic pain in the neck when picking out light bulbs and computer screens but great for matching socks after washing :).

I've always wondered about those new LED arrays, so I'm grateful for the insight in real life use..

[Scott L. Burson]

Shuji Nakamura needs to be mentioned here

I don't know anything about Naruhito Iwasa, and I'm sure this was a team effort, but the Nichia inventor who has received most of the credit for GaN blue and white LEDs is Shuji Nakamura, who received the 2006 Millennium Technology Prize for this work.

[ckaspereli]

The how and why but not the color details,,,

So sorry but i merely wish to make the humble point that the actual color of an LED isn't discussed by the author, merely how and, somewhat, why it works - I suggest you try and research highly protected IP on your own (good luck!),,,

[Michael Bishop]

Domestic LED bulbs are now good enough and cheap enough to replace CFLs (IMO)

I've had CFLs in my house for years - since the early days when they were made with a fluorescent tube, a iron-cored choke and a little starter in a glass jar. The early electronic ones were expensive and not quite as bright as the tungsten bulbs that they were supposed to replace, but Osrams were very reliable and easily lasted 8 years. More recently I bought a stock of Feit CFLs; they are cheap and very bright but barely last 8 months, and 'recycling' them is a pain. So I am more than ready to change over to LEDs.

I remember early LED lamps as dim and very blue, with terrible colour rendering. But technology improves, and the latest ones seem very good to me. I've bought several 3W GU10 and E24 bulbs from three of the cheaper brands, for £5 to £8 each. They are rated as 3000K, but look less orange than warm white CFLs (which is a good thing in my opinion). I'm been impressed by how much light you get from a 3W bulb. I have replaced 200W of halogen with 15W of LEDs in the kitchen. The room is not as bright as it was, but it is bright enough, and the energy saving is massive.

There are small but visible differences in spectrum and colour rendering between the three types, but none is unacceptable to me and the £5 diffuser bulbs from Lidl are superb. (I've done the resistor colour code test and there's no problem at all.) So far, there have been no failures, although I've only had LEDs for a few months so it's too early to draw any conclusions about lifetime. If you've previously looked at LED lighting and hated it, perhaps it is time to take another look. It may not be perfect, but modern LED technology is not as bad as some Reg commentards like to claim.

[John 62]

home lighting circuits

any reason why we can't have low voltage home lighting circuits that LEDs can plug directly into? Or at least fixtures with two parts, one for the control/transformer circuitry and one for the LED(s)?

[Stoneshop]

Re: home lighting circuits

Well, theoretically one could, yes. As long as the LED assembly has a way to signal the controller what the maximum current is it can handle (the controller could decide to supply less, for the sake of dimming), and that way being standardised across bulbs and fixtures.

[rciafardone]

AN vs A ... Correct use

My English is a little fuzzy right now, but shouldn't it be "A LED" instead of "AN LED" since its preceding a word starting in consonant and not vowel. This is the kind of error that should not be. EVER.

[madestjohn]

Re: AN vs A ... Correct use

The a or an rule is phonetic not text based, its based on the soft vowel versa hard consonant, hence while its an honest mistake to make we must present a united front against the creeping self righteousness of grammar nazis consciousness

So it depends on how you choose to pronounce LED

Besides it english, .... It wouldn't be half as fun if it actually made logical sense

[CCCP]

Re: AN vs A ... Correct use

@madestjohn

Ahhhh, I can't resist. If you're correcting a correction, united front or not, grammar and spelling mistakes are the poisoned spawn of Wayne and Waynetta.

it's = it is

its = possessive form, belongs to something

Oh, LED pronounced as lead (the metal) makes no sense. So it's always "an" LED following the phonetic rule.

[SirDigalot]

if it looks good to you use it, if you work with it professionally use whatever it is you want to.

at home I am thinking bottom line cfls are cheaper leds at least at most major box stores here in the southern US are too expensive to replace, though I might use them when we redo the kitchen, dunno that's a log way off too.

most of my life is spent looking at a cursed monitor, I have colour issues too so matters little what others think, you don't like my lighting in my house then you can't have my beer or you can keep quite get drunk and not care....

[madestjohn]

... Beer?

Ahhhhhh

[Flash_Penguin]

Check IR led with a camera

Top tip for the new year

[Anonymous Coward]

Bootnote

I highly doubt incandescent bulbs produce enough heat to offset my heating bill in average -15C climate. How about it warmer climates? Do you guys find it gets cold when the lights are out or dimmed?

[Phil O'Sophical]

Re: Bootnote

Replace a 100W light with a 15W light and you've got 85W less energy going into the room. Natural variations in temperature being what they are, you might not notice the tiny drop that will result, but if you have a thermostat on a heater that is keeping the temperature constant then it will ask that heater for an additional 85W. That's just how thermostats work.

[Taisto Leinonen]

Car dashboard

Street illumination with LED luminaires is uprising. Homes are illuminated with LED lamps, with the exception of saunas, where a tungsten-wire bulb at the temperature of 100 oC is still the only choice (my sauna in Helsinki, Finland, built by my father in 1946 was originally lighted by a petroleum lamp - still operational when old memories strike me).

But and but, when ever will we see cars equipped with led-illuminated dashboards, wherein no indicator lamp ever goes out. My good friend on the adjacent lot spent 3 hours to replace 24 indicator lamps in the dashboard of his Citroën Xara.

[Simon B]

Last 50 times as long - do they bollox!

Not to forget they cost 20 times as much.

Shame.