Interesting new possibilities for LED lights published in Nature recently suggesting that the end of the incandecent bulb may be in sight .

http://www.nature.com/news/2006/060410/full/060410-8.html
and
http://news.bbc.co.uk/1/hi/sci/tech/4906188.stm

Edison Screw or Bayonet Cap I wonder?!

Happy Easter All

I doubt incandescent lamps will ever go out of production.

For one, regular bulbs have a certain spectrum of light that can't be duplicated by any other type of light.

You can't really do mood lighting with fluorescents, for instance. Dimming those just looks nasty - all putrid blue.

Hey, carbon-filament bulbs are mostly obsolete, except for ornamental lighting.

And THOSE are certainly still manufactured!!

Read those two articles. The 'Nature' original, full of concise factual information on the science, the technology, the future feasibility and shortcomings.
Then I read the putrid BBC report, dumbed-down for a dullard mass-media audience and an insult to the intelligence.

Alan

I think LED lamps will be a few years away.

Hee!, they are great for traffic lights and railway signals but they still miss the yellowish glow which we like in our houses.
The colour rendering is not too good because LED's have a monochromatic light output.
Incandescent lamps provide in winter some extra heating too
An other thing is costs. A 240 volts LED lamp will probably cost at least NZ$100, ( US$60 ) as direct replacement for a normal bulb.
See what happens??
Give it at least another 10 years I think.

My $0.02 worth.
Considering that an incandescent lamp loses 94% of it's output as heat, it should be only a short period of time before it's demise, colour-rendering or not.
LED technology is advancing in leaps and bounds and has been in the last 5-10 years as opposed to the development of the filament lamp since it was invented, in the 20th Century.
Most of what is driving industry these days is finding a better, low power alternative to the light bulb.
With singular LED outputs in the thousands of milli-candelas and with such a low current, it will be a short amount of time before the incandescent source is made obsolete.
Couple that with the 300,000 hour life on an LED fitting.
Take your pick.

I agree with Mike here, the advantages are to great to be ignored. I think we will see a rapid move to this technology.

Besides if you look at history almost everyone that has said "That will never happen" has been proved wrong.

LED lights are already here. Indicator lights on switchboards & control panels are all LED now, and my torch has an LED bulb. Christmas lights are going LED too ! Cars are using LED headlights now.

I think the incandescants days are numbered.

The LED replacements would have to become as cheap as CFL's before they become prominent forms of domestic lighting. For other applications the incandescent lamp is pretty much obsolete...everything to do with signalling or indication is now using LEDs or about to. Portable lighting is rapidly changing now. LED torches have been around for a few years but today I saw a 12v lead lamp shaped like the familiar flourescent ones but internally was a panel of white LED's. The LED headlights on cars are the most vile thing I have seen and would ban them if I could. It is extremely unpleasant to have that 'spectrally pure' light shining in my eyes from an oncoming car.
My stash of several thousand incandescent bulbs should see me out while the rest of the world has converted to CFL's & LED's. There really needs to be a 'warm white' LED for it to be acceptable. But then again, some people have no concept of colour temperature...the use of cool white CFL's in a living room proves that.

I didn't come floating down the Thames on a chocolate biscuit wrapped in bacofoil and I'm not paying $50 for a 60W lightbulb either, even if it does last 34 years. By then I'll be in my mid nineties and past caring. LEDs? Another catchpenny for people with more money than sense.

Alan

Sorry,
That figure of 300,000 hours is incorrect.
Lets try 100,000 hrs.
Regardless, that is 100 times what you can expect from an incandescent lamp.
AS240,
Here's a funny story, I use an old twin 2x 9W PL-S fitting here in my office to give light in here at night instead of using the normal room lights.
Anyway, the current 4000K lamps were starting to get rather blackened and I thought it was time to replace them.
Go down to my local supply house and get what I thought was the correct lamps and bought them home and proceeded to tear the boxes open and fit the lamps.
Switch the fitting on, Good God!, they are the wrong colour (2700K!) and it looks like I have an HPS street-light on in here.
The nieghbours must be thinking I'm growing some drugs in here.
I won't get caught like that again.

Who would?

At that price they will only be used for fixtures that are costly to re-lamp.

However I have no doubt that like all electronic stuff the price will nose dive once China, Korea etc start mass production of these.

CFLs where not nearly as cheap as they are now.

The LED lamps will make there way in mass production one day.
It will all depend upon price.
I have some CFL's in my lounge which have done 12000 hrs now and still going strong. NZ$7 (US$4) each so they were a good deal.
In my workshop I prefer the normal 5 or 6 footers Triphosphor tubes. ( these last for 15000 hrs + )
Nice bright and new tubes only cost NZ$3 ea.

For our normal lamps the filament lamps are the most practical option at about NZ0.89 ea. with their usuall inefficiencies. (they go for about ±800 hrs).
As you know I'm the meterman and have quite a few meters hooked up in my house to do these surveys.
Edited to add something in I forgot.

[This message has been edited by RODALCO (edited 04-16-2006).]

I have seen a few newer cars in my area with funny looking tail lights. On closer inspection i find they are lots of smaller lights clusterd together to make up one normal sized brake light. Not shure if these are LCDs or not but it looks like they are and becoming more popular with car makers. (my 6 year old ford sill has proper lights that normaly fail its MOT)

There are certainly LED tail lights and signals in use on railway vechicles here. The tail lights look like clusters of bright LEDs.

Some piccies from LED traffic lights in Auckland N.Z.
We have problems with some of the orange LED lamps, which seem to have a few faillures that sections of 4 to 5 LED's are not working.
I have spotted about 10 faulty orange ones over the last year, and reported them to the councils to get replaced under warranty.
The irony is that the orange lights are ON for the shortest time, you expect them to last the longest.
The red ones do most ON hours but I haven't seen those faulty yet.
Could have been a faulty batch with a cracked circuit board or series resisitors, or LED's??
http://static.flickr.com/53/131302228_a5a86c9829.jpg http://static.flickr.com/45/131301312_28773dd0c4_o.jpg http://static.flickr.com/55/131301311_b0b65e12ab.jpg http://static.flickr.com/1/131300136_fd70b17b83.jpg

Soon someone will invent an LED that gives out the same light as an incandescant. Then it will become feasible to have LEDs in the lounge.

I have lots of downlights in my home and I'm forever changing bulbs. If LEDs last longer then I'm willing to pay extra for that privelege.

Hi Kenbo, and welcome to ECN.

LED lights on cars have been creeping in over the last few years. First it was just LED versions of the third, high-level brake light, now they're sometimes used for brake lights and turn signals too. The latter really catch the eye, as the light snaps on and off very smartly.

Out here in the boondocks we have to go miles to find any traffic lights, but over in Norwich I've noticed a few LED versions appearing in the last couple of years, including one intersection which has LED for all aspects. Some of the others just seem to have LED for the reds.


What's the sequence of N.Z. lights? Do you go straight from red to green like American lights, or do you have the British-style red-&-amber combined phase before green?

Hi pauluk

The NZ traffic lights are sequenced to go straight from Red to Green.

They are not sequenced like in the UK and Germany that Red and Orange are coming on at the same time prior to going to Green.

It has probably something to do here with people driving a lot through Red lights while the other ones have gone Green. If the extra phase, Red Orange, was given as a pre warning for Green we would probably have a lot more crashes here. Especially in Auckland

Regards Ray

Orange light before green...first I've heard of this. It's not like you need a warning to slow down or something.
However, I do notice of late where there's traffic lights for the sole purpose of a pedestrian crossing (ie. not at an intersection) the orange light flashes a few times before you get the green light. The only reason I can guess this is for is to remind you to check the crossing before taking off. Incidentally, when new things like this appear there isn't any publicity about what they mean...seems to be left up to you to guess.
As much as I dislike LED's for general lighting, for car brake lights they do have the advantage of alerting the driver behind faster. Apparently, the time taken for an incandescent filament to warm up and become visible does mean the difference of a few metres stopping distance for the car behind.

France.

Red = Stop [optional].

Amber = Stop [optional].

Amber, (flashing) = Shut eyes & go.
[Used at road repairs/ temporary signals etc.]

Green = Overtake, [up the sidewalk].


Alan

I imagine this one is identical to the UK where the flashing yellow allows you to proceed if/when the crossing is clear of pedestrians.

BTW when visiting Oz a few years ago, it took me some time to work out what a “PED XING” was on your American style (worded) road signs. It finally twigged when I nearly ran over one! Just joking!


[This message has been edited by Hutch (edited 04-21-2006).]

I've never really seen the point of the red-&-amber phase here. All it seems to do is encourage certain drivers to start off before green. It's also interesting to note that where we have a separate green "filter" arrow for turns, that can just come on with the red without any amber first.

Our neighbors across the water in Ireland have lights which just go straight from red to green, as do those in the Channel Islands.

By the way, we do not have any amber or red arrows, and for North American readers, neither do we have turns on red (except where there's the aforementioned green arrow illuminated simultaneously).


As Hutch said, that's standard for our pedestrian crossing lights. It's not used where there are also pedestrian lights at an intersection with regular lights. It's only on the lights which are normally located in the middle of the block with the sole purpose of stopping traffic for pedestrians to cross.

Whereas American lights flash the "Don't walk" or "red hand" immediately before going back to the solid "Don't walk" indication, ours flash the "green man" (walk) signal, and the amber for cars flashes at the same time.

http://www.highwaycode.gov.uk/signs01.htm

http://www.highwaycode.gov.uk/18.htm#172

They've started introducing different types of pedestrian crossing lights recently though, some of which now use the regular red/amber before green. Why we need a half dozen different types with varying light placement and different sequences, I have no idea.




One thing I have noticed about some French lights is that there's actually very little difference between the colors. In the U.K., the U.S., etc. red and amber are clearly and distinctly red and amber.

Some of the lights in France seem to use a reddish-orange for one and a not-so-reddish-orange for the other, and at first glance you can't actually tell which is which (without looking at the position on the signal head).


I've had to explain this American sign to a few fellow Brits before:




[This message has been edited by pauluk (edited 04-22-2006).]

The irony is that the orange lights are ON for the shortest time, you expect them to last the longest.
The red ones do most ON hours but I haven't seen those faulty yet.

How is the life span of LEDs calculated? are the like incandecants where they have xyz hours life. Or are they like flourecents where you shorten there life the more they are switched off and on?

Kenbo, Welcome to ECN.

Leds: Their lifespan is based upon 'running' hours at their nominal operating voltage and current. ( around 100,000 hrs )
In case of Red Led's 1.7 volts dc 20 mA
Yellow and Green Led's 2.2 volts dc 20 mA
Blue and White Led's 3.6 volts dc 20 mA
to give some examples. ( Data sheets are usually available from the LED suppliers.
and quoted values above may vary a little )

An LED is a light emitting diode. In forward biased mode at the U.nom and I.nom, the LED emits light. Is an LED subjected to a higher current The LED will overheat and fail eventually or loose a lot of it's brightness before failing altogether.
An LED does not like to be reversed biased and a reverse voltage of about 5 to 6 volts dc can be fatal for the LED.
An LED can be pulse driven at a lot higher current provided the ON OFF ratio is adequate for a cool down period of the LED.
e.g. 100mA for 50mSec and OFF for 500 mSec.

Under normal running conditions LED's don't get warm at all.

The newer Luxeon LED's like the 1, 3 and 5 Watt types are a whole different cattle of fish. These are supplied with data sheets and have to be adhered too otherwise they will fail earlier than expected and they are expensive to destroy by means of a wrongly applied voltage and the like.

An LED is not affected by the amount it's switched ON or OFF.
Effectively at 50 or 60 Hz ac the Led will pulse at the frequency. It's important that an antiparrallel diode is fitted across the LED to protect it from reversed applied voltage.

In traffic lights LED's are usually fitted in strings of 5 or 6 in series with a suitable dropper resistor to avoid loosing all the LED's in case one LED failed.

Led on photo is Red LED on 230 Volts 50 Hz
2 x 33k resistor and 1N4007 diode in series.
1N914 or eq. in antiparrallel.
yields about 3 mA through LED for a long lifespan.



edited for typo's and photo insert. Raymond

[This message has been edited by RODALCO (edited 04-26-2006).]

[This message has been edited by RODALCO (edited 04-26-2006).]

[This message has been edited by RODALCO (edited 04-27-2006).]