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back to article 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 …

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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.

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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.

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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.

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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".

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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.

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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!

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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.

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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...

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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.

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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).

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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.

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Anonymous Coward

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

Mostly frickin' hot, I think.

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

cant bloody remember....

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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.

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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.

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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.

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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.

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Unhappy

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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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Stop

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.

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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.

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Vic
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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...

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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....

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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.

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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.

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FAIL

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.

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Vic
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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.

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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...

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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.

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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...

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Anonymous Coward

Re: Overkill?

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

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Headmaster

Re: Overkill?

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

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Happy

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.

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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.)

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Go

Re: Overkill?

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

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Coat

You could say...

that this technology LED the way for some amazing innovations

[logo obvious]

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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?

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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.

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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.

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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.

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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.

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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".

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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

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