LED domestic lighting

[Andrew Chesters]

Has anyone used

or any direct equivilent? I'm thinking of using them as a part of a scheme in a lounge.

Any thoughts?

[Ian Stirling]

I have no personal knowledge of this product, I'm basing this on knowledge of the state of the art in LED lighting. Ok, so these are 40 quid for 6 lights. So, take off 20 quid for transformer and packaging, that's maybe (being generous) 3 quid per light. For that, you'll get something that emits as much light as at best a 1W bulb. (the blue however will be the equivalent of a larger bulb with a filter, but will not be much if any brighter than the white).

So, at best you're looking at something that will do 'mood lighting' (as long as you'r feeling in a dull mood), and emit about as much light as (in total) as a 5W night-light. At best, if they are making absolutely no profit, and producing in high volumes, with the leading-edge LEDs it might be three times this.

I'm not saying these are useless, but not for overall room lighting.

[TonyK]

I paid £12 a lamp (bulb) for mains voltage LEDs to replace 14 x G50 halogens from a wholesaler (I think retail was about £20). I took them back within a day and got a refund. Abso-bloody-lute waste of time :-(

So for £40 for 6 don't expect too much.

[Trevor Smith]

Check out this site

Smith

[Mike]

Don't bother. Wait a couple of years though and there are some good products coming.

[brugnospamsia]

I suspect these are for ornamental purposes.

It'll be a while yet before LEDs can replace quartz halogens...

Personally, if I was looking for that sort of effect I'd probably buy the LEDs seperately and make my own.

[Ian Stirling]

which there are blatant lies.

18 LED 'equivalant to 20W'.

At the bleeding edge, with devices that are only in lab quantity, 3W maybe.

Hmm, it also states "25 lumin brightness". (as measured by the Moomin standard institute.)

Which is (about) a 2W bulb.

(the absolute brightness of a 30 degree circle may be similar to a 20W omnidirectional bulb)

[Anna Kettle]

Do you know any more about this than I do? ie is this a couple of years as in 'some indeterminate time in the future' or as in 2007? Some year soon I'll be getting my house rewired and as I think the range of light fittings on the market at the moment is appallingly limited and ugly[1], I'm tempted to wait for the next generation of LED lights and design my own fittings around them

[1] A big problem seems to be the dilemma of either having the bulb glaring straight in the eye or having a large blob of opaque something to hide the bulb. And does _anyone_ like twiddly brass effect wall lights with cloth hats on the ends? I suppose someone must cos they seem to sell a lot of them

Anna

~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repairs / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____|

01359 230642

[Ian Stirling]

Indeterminate time in the future.

LEDs have a fundamental problem, that does not seem to be going away soon. Even if they were made as efficient as fluorescant tubes, there is still a lot of heat to get rid of. And LEDs have to be kept very cool, compared to other light sources if you expect any life out of them. Getting rid of 50W of waste heat, when the bulb can heat to 200C above ambient without problems is trivial. Getting rid of 20W of heat, when it can only heat to 30C over ambient is rather harder.

Even neglecting this, at the moment, the price of LED lighting is around

2-3 quid a watt, in largeish quantities.

It can be appropriate in some situations - it's much more efficiant for coloured light, as none is wasted in filters, or if access to change the bulb is very expensive.

And, the best white LEDs produce only about a third as much light per unit power that fluorescants do.

(typical ones are around as efficient as halogen bulbs.)

Halogen capsules are probably the most flexible light source at the moment, design your lights round them. LEDs aren't magic. What do you imagine your ideal light to look like? There may be other ways.

[Andy Wade]

Isn't that the opposite of the glumin - the SI unit of darkness :-)

[Andy Wade]

Indeed. Another issue that a lot of people seem unaware of is that LEDs get dimmer with age - in lighting-industry-speak they suffer from 'lumen depreciation.'

An example of this can be seen on many computer keyboards. If you normally have NumLock mode on all the time, but CapsLock rarely, and the keyboard is a year or two old then you'll probably find that the CapsLock LED is noticeably brighter than the NumLock one.

[The Natural Philosopher]

Let me know when you do. I agree with you.

In the meantime there is always Jim Lawrence.

[1] A big problem seems to be the dilemma of either having the bulb

We have black iron ones with paper caps on the ends. The best of a bad bunch.

[Bob Eager]

Interesting, and I'm sure it's true. But (despite having NumLock on much more than (particularly) ScrollLock), I can't see a difference on my 12 year old keyboard! Must have used high quality stuff in this!

[Owain]

"Andy Wade" wrote | Ian Stirling wrote: | > Hmm, it also states "25 lumin brightness". (as measured by the Moomin | > standard institute.) | Isn't that the opposite of the glumin - the SI unit of darkness :-)

Have those in the house and you would be rooming in the glumin.

I thought the glumin was the time you have to hold pieces of wood together for them to stick. 1 glumin in the instructions = 20 mins real time.

Owain

[Anna Kettle]

Oh! I didn't know that. Surely it is possible to produce light without heat. They do it with mirrors ...

So ideally the LED is coated in ZZZ which is transparent and conducts heat well ... when the ZZZ is thick enough the heat will conduct away to the air ... and the diameter of ZZZ for this to be successful is about 50mm ... 'Bout the same size as a normal lightbulb. DOH!

How many watts are needed? 20 as with a fluorescent bulb or 100 as with a filament bulb. Presumably the initial cost can be offset against running costs to some extent

There might be some interesting effects to be had using coloured LEDs together with white light sources in a room though I have to admit that at the moment I can't think of anything that would actually be attractive

Ah them. Lots of thin black wire and paint and brilliant spots of light. Just like an interrogation chamber

Yes it might be possible to do something interesting with halogen capsules.

I have no idea at the moment cos this is the first time I have started to think about it. First I have to suss out the options and find out their limitations. OK so no LEDs for actually shedding light

Anna ~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repairs / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____|

01359 230642

[Anna Kettle]

I will do, though you will have to wait awhile. Light fittings counts as "finishing touches" and as such will be done in the second five years :)

Wrought iron looks good in timber framed houses. Jim Lawrence's lights wouldn't do for me cos I will want to design my own and until that day comes el cheapo will do fine

Anna ~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repairs / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____|

01359 230642

[Mike]

I've seen prototypes of a new LED that still isn't quite as good as halogen but will be much nearer. It is targeted at automotive headlights. Lifetime is getting there as well but costs are still too high for production now but I'd expect to see these mid-2006 at the latest. How long it then takes for these to appear in domestic lighting units isn't up to the semiconductor manufacturer of course.

[Ian Stirling]

Low pressure sodium lights are (IIRC) the most efficient lights available. They produce little waste heat, but are just basically yellow light, so not ideal for most home lighting.

Nope. The heat is (about) the same for the amount of light. But the bulb has no problem with a surface temperature of a couple of hundred C. However, if the LED gets much over 50-60C, its life drops by lots. So, you need a much larger heatsink.

Unfortunately at the moment, it's about the same running cost as filament lighting, maybe a little better, so the running costs are not significantly lower.

The best idea would probably be variable colour temperature, but that has problems of its own (patterns of differing colour)

Well, the actual light is pretty much the same, whatever it comes from, it's how you diffuse it or concentrate it that makes a difference. There are other options, but unfortunately in general (some of the more exotic metal halide bulbs) they are rather expensive, need specialised ballasts, and may not be available in 20 years.

[Mike]

Any idea why many local authorities changing over to those bluey-white lights (mercury discharge ?). How do they compare efficiency wise ?

[Grimly Curmudgeon]

It was somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Mike" saying something like:

Powered by vapour?