100w Light Bulbs.

[D.M. Procida]

OK, I think I might be prepared to take that back.

I'm reading Oliver Sacks's autobiography, _Uncle Tungsten_. It describes his fascination with metals as a small boy, and the factory where his Uncle Dave made lightbulbs 60 years ago under the breand name "Tungstalite".

His description of creation of the electric lightbulb from elemental substances - metal, glass, gasses and acids - wrought in fire and delicately coaxed into globes and coils and spidery structures - is almost alchemistic.

I find it hard to imagine the same aura of magic surrounding fluorescent bulbs, or LEDs.

Daniele

[unopened]

Well, actually...

I'm no fan of CFLs, but it it is possible to obtain 'instant-on' CFLs that come on at something approaching full brightness (I know, 'cos I have some), and, as far as I understand, manufacturers are producing CFLs that can cope with frequently being switched on and off (as in stairwell applications). The problem is, it is extremely difficult to ensure that you buy one with the properties you want. I suspect manufacturers know full well about the problems and are quietly engineering solutions and putting them out, while all the time allowing the impressionable to say "problems? what problems?".

Once LEDs get a bit cheaper, they'll probably be ideal for your driveway - they don't care about being switched on and off, so if engineered properly, they could be a 'fit once and forget' option.

Oh, and as for the 'no fan of CFLs' - I'm not rabidly anti- CFLs in all guises. They are good for some things, but they are not a panacea, which some people seem to think.

Cheers,

Sid

[Dave Plowman (News)]

Think you're basing that on LEDs as used for low power applications.

[Rod]

Totally agree. The pack information is utterly inadequate for decision making - it always ends up as buy-and-try.

A cryptic '827' really conveys little to me - let alone those who have even less idea about CRI and colour temperature.

The packs/lamps usually don't have physical dimensions. And even is you know the overall dimensions, the shaping around the collar can preclude their use in some applications.

Terms like "quick start" mean different things to different people. We have some that come on pretty much immediately at near full brightness. Others that take a second then come on a low brightness. I'd guess both could be called quick start as they don't take 10 seconds before starting!

[unopened]

Yes - and I guess that's another unwarranted assumption biting me on the bum again. Your implication is that high power LEDs don't like being switched.

That would strike me as odd, though.

The biggest issue that I know of with high power LEDs is heat dissipation. I would assume (and there's that word again) that a commercial LED light fitting would make appropriate arrangements for dealing with the heat, which leaves switching. Given that LEDs have been used in outdoor animated advertising and TV screens for some time now, I would have thought that switching wasn't a huge problem - but please do enlighten me - I like to understand these things.

Thanks,

Sid

[Dave Liquorice]

Having looked at more bulbs. Yes "perl" "soft tone". Perl is a frosted inside of the envelope, "soft tone" looks more like a paint layer.

I should imagine there is. Did you see my post about what I found in Tesco yesterday? I looked in the local Co-op today. 11W CFL (60W equiv/similar on the box) 600 lumen. Next to it a 60W bulb (perl IIRC) 700 lumen. Big gap where the 100W tugnsten should have been, obviously more brains up here than down in Carlisle. B-)

Having looked at quite a few "60W" bulbs in CFL and tungsten formats it appears there *is* a generic misrepresentation going on. An 11W CFL has an output about 600 lumen, a 60W tungsten about 700 lumen as stated on the pacakaging. I think I'll be wandering over to the ASA site later, I suggest that others do a bit of research and tell the ASA their findings as well. The ASA will only act if it gets complaints.

[John Rumm]

Even if they marked them more honestly up front, there is also the issue of the loss of performance in a relatively short time. Yes, GLS will loose performance as well, but it tends to be a linear decline with age, many CFL IME seem to lose something like 20 - 30% output after a few months - well before their supposed end of life. (and you can't even fit a more powerful bulb and tame it with a dimmer in its early life!)

[John Rumm]

I don't think there is much of a switching issue with LEDs designed for lighting.

Indeed this is more of a problem. Many people will make assumptions about LED lighting based on their experience of LEDs as used for indication purposes etc - i.e. low power, high reliability, long life, fast switching etc. Alas that does not seem to extrapolate well to trying to light a room with the things.

The main problem seems to be when you push the devices much much harder to get the required light output, and also you are attempting to get something other than monochromatic light from them. (White LEDs seem to be blue LEDs (themselves less efficient than other colours) with a fluorescent coating). Often they are packaged in numbers close together which makes heat dissipation a problem. Quite often they are then wired with banks of LED in parallel to reduce the number of dropper resistors required - which given the natural manufacturing tolerances of the LEDs you usually end op with some being overdriven. These then tend to fail first. It seems quite common for even relatively new LED lamps to have a number of failed LEDs.

[The Natural Philosopher]

semiconductor degradation is purely a function of heat and time, and switching makes no difference to te actual LED. Hoever the othermain failure mode of semiconductors not exposed to electrical overload, is thermal cycling disrupting the seals and allowing air in to poison the semiconductor junctions. So heat cycling is not good here.

I haven't thought it through, but a capacitor in series with a pair of back to back leds in parallel, with maybe a surge resistor, should be all you need for a mains LED light.

LED efficiency aint up there with a fluoro tube tho.

[The Natural Philosopher]

I find the 11W units are about 40W equivalent.

Need to go to 17W to get a 60W unit equivalent.

[Dave Plowman (News)]

Most of the circuits I see tend to have LEDs wired in series - if low voltage of course there is a limit - so perhaps several series chains up to that limit wired in parallel. That's using a proper driver.

[dennis]

I have had so many free ones I give them away. Didn't have a very small one though so I had to buy a 7w one. 8-(

[dennis]

"D.M. Procida" wrote in message news:1it9mot.vhfptytcpzqdN% [e-mail]...

Anything difficult to understand is magic to some. To some of us nothing is complicated enough to be magic. Most sit between the extremes.

[ransley]

New ones are better but here in the US we get a bit colder than you lucky folks, down to -20 farenhite thats -30 c, at that temp it takes about 15 minutes to get the flood type bright and 5 minutes for cfl type.

[Jules]

Bit colder still in my part of the US, and CFLs plain don't work outdoors in the winter. Thankfully there still seems to be a plentiful supply of incandescents here. (I also looked at some special low-temp tube fluorescents the other week for our garage, but even they were only rated down to -20F). We've got some big halogens in the outdoor security lights though, and haven't had any problems with those. Some low-voltage halogens for the out-buildings might be the way to go...

[ARWadsworth]

Although not an advert the Geenpeace web site says that CFLs life expectancy is not affected by frequent switching

and

make a claim of how much mercury they save over incanesants where coal is used to power the electricity stations.

The only fact I am sure of is the testing of the failure rate of CFLs. More that 50% of a sample of CFLs must still be working after 3000 ignitions over the given lifetime(specified by the manufacturer in hours) to allow the life span to be stated on the packaging. I am however, so far unable to find out if the goal posts have moved as to the on and off time periods that are now/were in use.

Adam

[D.M. Procida]

And some of us understand the different ways in which the way the word "magic" might be used...

Daniele

[Dave Plowman (News)]

But what they don't say is under what conditions the lamp is tested. Vertically - and which way up? Horizontal? At an angle? Ambient temp, etc? (Some which are said to have a very long life don't like being in a fitting - they get too hot)

If they get away with blatant lies about efficiency relative to a filament lamp you can bet your bottom dollar they'll do it here too.

[Bob Eager]

Whoooosh!

[ARWadsworth]

If I could find IEC 969 (along with IEC 60968, IEC 60969 and IEC 55015) for free I would let you know.

The best I can find is at the moment is

am still looking for more.

I have little to say as you can read it yourself.

Adam

PS What is a bottom dollar worth these days, less than a quid?