In article ,
Steve writes:
Andrew Gabriel wrote:

The mean brightness is still the same, since the mean current must be
the same,


Actually LEDs get slightly more efficient at higher current, so
the mean brightness is higher.

That certainly used to be true, but again for the Luxeon jobbies we use,
it ain't anymore.

Furthermore, it appears that eyes don't perceive mean brightness,
but perceive something which is between the mean and peak brightness,
so a flashing light will appear brighter than a steady light of the
same mean brightness (over some frequency range).

Neither of these effects is very large though.

Is this a medical fact ? In recent discussion on sci.elect.design, this
effect was poo-poohed by several of the engineers in there whose
opinions I would trust.

I've seen it stated on a number of occasions. I have not personally
tested it but it sounded plausable. BTW, the frequency range over
which it works is not wide. It needs to be above the optical fusion
frequency (varies from one person to another, but never higher than
70Hz), and below the frequency response of the receptors and optic
nerve (which I believe is always over 100Hz, well over in some people).
One person I spoke to about it a while back didn't think the frequency
response of the optic nerve was the upper limit for the effect to work
(thought it was higher). These frequences vary a little across the
field of vision too, and with other factors.

--
Andrew Gabriel

In article ,
Andrew Gabriel wrote:

I've seen it stated on a number of occasions. I have not personally
tested it but it sounded plausable.

Early LEDs did have a light output that increased more than the
current increase, so it certainly made sense to operate LEDs in a
high current, low duty cycle pulsed mode. Modern LEDs are more
linear, so the only reason for pulsing would be to make the
brightness adjustable (or constant, as the battery goes down),
or maybe to resolve differences between the dc supply and the
LED's fwd voltage drop (but that would need an associated
inductor/transformer).

I have also seen the opinion on another newsgroup (c/w research
references) that pulsed LEDs can appear brighter in conditions
of low ambient light levels (ie, if our eyes are dark-adapted).

--
Tony Williams.

"dave @ stejonda" wrote in message
...

You can certainly buy cycle lamps with what are described as halogen
bulbs - btw, has the law been updated yet to allow cyclists to use
non-filament bulbs?

The only restrictions relate to steady lights and red to rear.
http://www.hmso.gov.uk/si/si1989/Uksi_19891796_en_1.htm
http://www.hmso.gov.uk/si/si1994/Uksi_19942280_en_1.htm

I believe some flashing lights are now allowed, but can't find that.

There are some new EL materials coming up that are between LED and
fluoro efficiency. see www.elam-T.com - but the most lucrative potential
market is in replacing LCD display technology, so don't expect to see
flat screen lighting yet awhile.

That's a fascinating site, thank you.

I even understood a very small part of it - even with my 50 years out of
date physics :-(

Mary

Arsenic is a medicine in small enough doses.

So is mercury. It's used as a preservative in injections for babies and
young children - at higher levels than allowed for adults ...

I'm not arguing for or against, just saying that pharmaceutical uses aren't
a reason for saying that something is safe. Oxygen is necessary for life yet
poisonous in some concentrations.

There are indeed some irrational oppositions to waste products, nothing is
without risk ...

Mary

Is there a certain frequency above which this pulsed light is considered a
continuous light and therefore acceptable as the continuous light required
under the Road Traffic Act or whatever legislation says that flashing
lights
on bicycles are verboten?

Is the Act enforced?

Mary

Owain

"Dave Plowman" wrote in message
...
In article ,
RichardS noaccess@invalid wrote:
Perhaps the law has changed, however, because I think that TVRs have LED
brake light clusters, don't they? (unless this didn't apply to the rear
lighting).

They're common as centre stop lights on cars. And as all the various tail
lights and indicators on buses. Oh - and the taillights on my BMW. And of
course there are HID headlamps (xenon) which aren't filament lamps either.

But they're not pedal cycles ...

--
*60-year-old, one owner - needs parts, make offer

I have my own Toy Boy, thank you :-)

Mary

Dave Plowman London SW 12
RIP Acorn

"Tony Williams" wrote in message
...
In article ,
Andrew Gabriel wrote:

I've seen it stated on a number of occasions. I have not personally
tested it but it sounded plausable.

Early LEDs did have a light output that increased more than the
current increase, so it certainly made sense to operate LEDs in a
high current, low duty cycle pulsed mode. Modern LEDs are more
linear, so the only reason for pulsing would be to make the
brightness adjustable (or constant, as the battery goes down),
or maybe to resolve differences between the dc supply and the
LED's fwd voltage drop (but that would need an associated
inductor/transformer).

I'm really glad I asked this question.

I think.

Mary
--
Tony Williams.

"Terry" wrote in message
...
Mary Fisher wrote:


"Mary Fisher" wrote in message
t...

I use LED lamps when caving and TBH they aren't brilliant (well they
are
but
they aren't too). They are ok if you haven't got to see very far (fine
in
a
cave cos the wall isn't usually more than a few feet away)

Er - I think I'd prefer to leave that activity to you :-)

Mary

Mary: I agree. I don't think I can even speleologically spell
that anyway! Terry.

It's T H A T, Terry ...

Mary

In message ,
"Mary Fisher" wrote:




Arsenic is a medicine in small enough doses.

So is mercury. It's used as a preservative in injections for babies and
young children - at higher levels than allowed for adults ...


Which (very OT) has got to be a good argument in favour of combined
immunisations (HIB/MMR etc.) rather than half a dozen separate ones.

Hwyl!

M.

--
Martin Angove (it's Cornish for "Smith") - ARM/Digital SA110 RPC
See the Aber Valley -- http://www.tridwr.demon.co.uk/abervalley.html
.... Answers on a postcard please to 10 Downing Street, London SW1.

In article ,
"Mary Fisher" writes:



Arsenic is a medicine in small enough doses.

So is mercury. It's used as a preservative in injections for babies and
young children - at higher levels than allowed for adults ...

Prior to antiboitics, it was used to treat VD.

Each person, on average, releases 3g of mercury into the
atmosphere when they are cremated, from tooth fillings.
That adds up to more than all other sources of environmental
contamination with mercury added together.

--
Andrew Gabriel

On 15 Jul 2003 19:45:36 GMT, (Andrew
Gabriel) wrote:

The white ones are UV with fluorescent phosphors, so they can
be made same colours as fluorescent lamps in theory, but I suspect
there's no demand for 2700K ones. Also, the efficiency of the
phosphor will reduce slightly for lower colour temperature and
at the moment everyone is after highest brightness, so that would
not be a lot of interest to manufacturers.

http://www.lumileds.com/ has a PDF about a forthcoming 3200k" Warm
White, Incandescent-Equivalent LED" shipping in August (it talks about
LEDs "rapidly gaining traction" in general lighting, ...we give them a
byootiful language and what do they do to it.............)
3200K is around quartz halogen colour temp (tho being flouro based I'm
guessing the "quality" of the light whould be like that of a Warm
White fluro)
IIRK one of the probs with white LEDs is the colour isn't stable with
time.

Lumileds has some impressive 5w suckers with heatsinks on the back
but it's Nichia's 50mW blue or violet lasers that I covet!

Arsenic is a medicine in small enough doses.

So is mercury. It's used as a preservative in injections for babies and
young children - at higher levels than allowed for adults ...


Which (very OT) has got to be a good argument in favour of combined
immunisations (HIB/MMR etc.) rather than half a dozen separate ones.

That's true if you feel it necessary to immunise children at all.

Mary

Hwyl!

M.

--
Martin Angove (it's Cornish for "Smith") - ARM/Digital SA110 RPC
See the Aber Valley -- http://www.tridwr.demon.co.uk/abervalley.html
... Answers on a postcard please to 10 Downing Street, London SW1.

wrote:
http://www.lumileds.com/ has a PDF about a forthcoming 3200k" Warm
White, Incandescent-Equivalent LED" shipping in August (it talks about
LEDs "rapidly gaining traction" in general lighting, ...we give them a
byootiful language and what do they do to it.............)

Could have been worse - they could have been rapidly gaining leverage!

3200K is around quartz halogen colour temp (tho being flouro based I'm
guessing the "quality" of the light whould be like that of a Warm
White fluro)

a CRI of 85 would be considered poor for a fluoro, but is good compared
with previous LEDs

IIRK one of the probs with white LEDs is the colour isn't stable with
time.

Lumileds has some impressive 5w suckers with heatsinks on the back
but it's Nichia's 50mW blue or violet lasers that I covet!

"Andrew Gabriel" wrote in message
...
In article ,
"Mary Fisher" writes:



Arsenic is a medicine in small enough doses.

So is mercury. It's used as a preservative in injections for babies and
young children - at higher levels than allowed for adults ...

Prior to antiboitics, it was used to treat VD.

I remember Golden Eye Ointment ... ah, those were the days!

Each person, on average, releases 3g of mercury into the
atmosphere when they are cremated, from tooth fillings.

Another good reason for burial :-) Or the newer fillings.

That adds up to more than all other sources of environmental
contamination with mercury added together.

I didn't know that.

Mary

--
Andrew Gabriel

"Mary Fisher" writes:





Arsenic is a medicine in small enough doses.

So is mercury. It's used as a preservative in injections for babies and
young children - at higher levels than allowed for adults ...


Which (very OT) has got to be a good argument in favour of combined
immunisations (HIB/MMR etc.) rather than half a dozen separate ones.

That's true if you feel it necessary to immunise children at all.

!!!!!!!!!

--
"The road to Paradise is through Intercourse."
The uk.transport FAQ; http://www.huge.org.uk/transport/FAQ.html
[email me at huge [at] huge [dot] org [dot] uk]

"Mary Fisher" wrote in message
t...


I wish I knew what you were talking about - but don't try to explain, I'd
forget immediately :-(

Mary



Interesting article in todays New Scientist suggest that further research
into tungsten filaments is showing that 50% efficiency may be possible - as
opposed to 25% for fluorescents.

I have posted the article at

http://nanohelix.tripod.com/ns.jpg

Dave

In uk.d-i-y, Martin Angove wrote:
Boy won't pick a sweet up
from the pavement, but might well be allowed to recover a slice of apple
dropped on the living room carpet.

This kind of distinction can usefully be rationalised as the "five
second rule". If it's been on the floor or pavement for more than five
seconds, you're not allowed to eat it. That rule is simple enough for
young children to remember, and gets the right answer pretty well most
of the time.

--
Mike Barnes

On Tue, 15 Jul 2003 22:01:58 +0100, Grunff wrote:

BigW has a habit of googling for every discussion topic,
and posting any links (s)he thinks are relevant, regardless of
how relevant they really are. It gets tiresome after a while.

Do you read Viz ?

The Roger Irrelevant strip ?

"Dave Gibson" wrote in message
...

"Mary Fisher" wrote in message
t...


I wish I knew what you were talking about - but don't try to explain,
I'd
forget immediately :-(

Mary



Interesting article in todays New Scientist suggest that further research
into tungsten filaments is showing that 50% efficiency may be possible -
as
opposed to 25% for fluorescents.

I have posted the article at

http://nanohelix.tripod.com/ns.jpg

I went to it eagerly.

I can't read it :-(

What's more, I can't convert it into a readable form :-((

Mary

Dave

Mary Fisher wrote:

I went to it eagerly.

I can't read it :-(

What's more, I can't convert it into a readable form :-((

What problem did you experience Mary? I can see it OK, and it's
well worth reading.

--
Grunff

Grunff wrote:

Mary Fisher wrote:

I went to it eagerly.

I can't read it :-(

What's more, I can't convert it into a readable form :-((

What problem did you experience Mary? I can see it OK, and it's
well worth reading.

--
Grunff

It does not work with netscape 4.7 but is viewable with netscape 7

Mary Fisher wrote:
I went to it eagerly.

I can't read it :-(

What's more, I can't convert it into a readable form :-((

What, you mean like from "science" into "English"?

It sounds a bit like me when the boss comes in and asks how its going...
Well, I've come up with this really energy efficient lightbulb, ermm,
except that I've only got it working in the near-infrared so far, and I
don't quite know how it works yet either. Oh, and it violates Plancks
law too. I'll get me coat.

Fascinating article though.

In message , Mary Fisher
writes
http://nanohelix.tripod.com/ns.jpg

I went to it eagerly.

I can't read it :-(

Through the power of PSP screen capture and OP12...

Bright future for the low-power bulb.

A STACK of ultra-thin tungsten wire could one day form the basis of a
super-efficient light bulb, converting twice as much energy to light as
fluorescent tubes and 10 times as much as ordinary light bulbs.

'The discovery, by Shawn Lin and colleagues at Sandia National
Laboratories in Albuquerque, New Mexico, also challenges Planck's law
of black body radiation, a century-old law of physics that predicts how
much light in each different wavelength a substance will emit at any
given temperature.

The key to the discovery lies in the delicate structure of the
iridescent material. It is made from orderly stacks of tungsten rods,
each of which is a mere 500 nanometres in diameter - within the range
of the wavelengths of visible light.

When the researchers heated the lattice by passing an electric current
through it, they found that it emitted up to 10 times as much
near-infrared light as Planck's law predicted (Applied Physics Letters,
DOI:
10.1063/1.1592614). "We don't quite know how it works yet," concedes
Jim Fleming a member of Lin's team. But they suspect that the longer
infrared wavelengths normally emitted from tungsten light filaments are
for some reason trapped in the lattice, and only escape as shorter
wavelength, near-infrared beams.

The researchers reckon that if they can make the tungsten rods even
finer, the wavelength of the emitted light will become shorter,
bringing it into the visible range. Lin estimates that with rods 100 to
200 nanometres wide, up to 60 percent of the energy flowing into the
lattice should be
converted into visible light.

These tungsten lattices could then be used to make filaments for
super-efficient light bulbs that are as bright as today's, but use a
tenth of the power to do so, and give off a twentieth of the heat. The
team has been granted two patents, with a third pending.

Amnon Yarrow, professor of applied physics at the California Institute
of Technology in Pasedena, is impressed by the work. But he insists
that the
discovery does not violate Planck's law, which he calls "one of the
towers of modern physics". "Rather it recognises that in very
sub-micron structures the law does not apply;' he says.


What's more, I can't convert it into a readable form :-((

Not sure what was wrong there.

--
dave @ stejonda

I went to it eagerly.

I can't read it :-(

Through the power of PSP screen capture and OP12...

Thank you very much. It WAS worth reading.

Mary

--


"ben" wrote in message
...
Mary,

Read Dave's 22:09 post - he's translated it for you

Ben

Have done. But thanks.

Mary

"Mary Fisher" wrote in message
t...


--


"ben" wrote in message
...
Mary,

Read Dave's 22:09 post - he's translated it for you

Ben

Have done. But thanks.

Mary


Hi Mary, sorry you appear to have trouble viewing the article. The only
thing I can think of is that you are using an older browser which cannot
handle highly optimised jpeg files, which includes progressive scanning. I
have re-uploaded the article without the progressive scan option.
I would be interested to know if you can now read it ok.

Thanks

Dave

PS Many thanks to the other Dave for doing an OCR on it!. That's some
program that can do that at that resolution, I would be interested in the
name of it. I normally have to scan at least at 600dpi to have any hope!

Dave

In message , Dave Gibson
writes
PS Many thanks to the other Dave for doing an OCR on it!. That's some
program that can do that at that resolution, I would be interested in
the name of it. I normally have to scan at least at 600dpi to have any
hope!

I used Paint Shop Pro to capture the image off screen (as saving the jpg
to disk and OCRing that wasn't at all successful). I then used PSPs tool
to remove some of the jpg artefacts before using Omnipage Pro 12
(www.scansoft.com) to OCR. OP12 didn't get the numbers right (too and
zoo instead of 100 and 200) and a few words/names got garbled but it
didn't leave much cleaning up to do.

--
dave @ stejonda

Hi Mary, sorry you appear to have trouble viewing the article. The only
thing I can think of is that you are using an older browser

Sorry, I don't understand what you mean by a browser never mind an older
one!

which cannot
handle highly optimised jpeg files, which includes progressive scanning. I
have re-uploaded the article without the progressive scan option.
I would be interested to know if you can now read it ok.

So would I - but there was no url ... :-)

Mary

"dave @ stejonda" wrote in message
...
In message , Dave Gibson
writes
PS Many thanks to the other Dave for doing an OCR on it!. That's some
program that can do that at that resolution, I would be interested in
the name of it. I normally have to scan at least at 600dpi to have any
hope!

I used Paint Shop Pro to capture the image off screen (as saving the jpg
to disk and OCRing that wasn't at all successful). I then used PSPs tool
to remove some of the jpg artefacts before using Omnipage Pro 12
(www.scansoft.com) to OCR. OP12 didn't get the numbers right (too and
zoo instead of 100 and 200) and a few words/names got garbled but it
didn't leave much cleaning up to do.

COR! What a lot of trouble I've caused :-(

I couldn't even highlight the original to process it in any way. Couldn't
save as, couldn't cut ...

Mary

--
dave @ stejonda

"Mary Fisher" wrote in message
t...


Hi Mary, sorry you appear to have trouble viewing the article. The only
thing I can think of is that you are using an older browser

Sorry, I don't understand what you mean by a browser never mind an older
one!

which cannot
handle highly optimised jpeg files, which includes progressive scanning.
I
have re-uploaded the article without the progressive scan option.
I would be interested to know if you can now read it ok.

So would I - but there was no url ... :-)

Mary


I do TRY to minimize confusion!
Same as befo-

http://nanohelix.tripod.com/ns.jpg

Dave

"dave @ stejonda" wrote in message
...
In message , Dave Gibson
writes
PS Many thanks to the other Dave for doing an OCR on it!. That's some
program that can do that at that resolution, I would be interested in
the name of it. I normally have to scan at least at 600dpi to have any
hope!

I used Paint Shop Pro to capture the image off screen (as saving the jpg
to disk and OCRing that wasn't at all successful). I then used PSPs tool
to remove some of the jpg artefacts before using Omnipage Pro 12
(www.scansoft.com) to OCR. OP12 didn't get the numbers right (too and
zoo instead of 100 and 200) and a few words/names got garbled but it
didn't leave much cleaning up to do.

--
dave @ stejonda

Thanks for that, I'll give it a look.

Dave

In article , Mary Fisher wrote:

http://nanohelix.tripod.com/ns.jpg

Then, when it had finished loading, it shrank to about half the screen size
and looked just the same as before.

Are you using Internet Explorer? Try going to "Tools - Internet
Options... - Advanced" and turn off "Automatic image resizing".

Hope that helps,

Andrew

--
Andrew Flegg -- | http://www.bleb.org/

On Sat, 19 Jul 2003 09:49:09 +0100, "Mary Fisher"
wrote:

COR! What a lot of trouble I've caused :-(

I couldn't even highlight the original to process it in any way. Couldn't
save as, couldn't cut ...

Mary

Keeping your software even moderately up to date can only help prevent
this in future.

Take Care,
Gnube
{too thick for linux}

Great! While it was coming on the screen I was composing orders of
superlatives. It was brilliant!

Then, when it had finished loading, it shrank to about half the screen
size
and looked just the same as before.

I wish I could show you! But I'm not complaining, my rubber bands

As it's just the image alone rather than in a web page, MS IE is being
'clever' and shrinking it to fit the window.
After it has loaded, wave the mouse somewhere else, then bring it back over
the picture and an icon will overlay the bottom right corner. Click to get
it back full size.

Toby.

"Gnube" wrote in message
...
On Sat, 19 Jul 2003 09:49:09 +0100, "Mary Fisher"
wrote:

COR! What a lot of trouble I've caused :-(

I couldn't even highlight the original to process it in any way. Couldn't
save as, couldn't cut ...

Mary

Keeping your software even moderately up to date can only help prevent
this in future.

1] saying that makes no sense unless you know what is out of date and
suggest an alternative. You shouldn't assume that my software is out of
date.

2] this is the only time I've ever encountered this problem

Mary



Take Care,
Gnube
{too thick for linux}

"Andrew Flegg" wrote in message
.. .
In article , Mary Fisher
wrote:

http://nanohelix.tripod.com/ns.jpg

Then, when it had finished loading, it shrank to about half the screen
size
and looked just the same as before.

Are you using Internet Explorer? Try going to "Tools - Internet
Options... - Advanced" and turn off "Automatic image resizing".

Hope that helps,

OK, I've done that. I'll give it a whirl when I've put the bread in the
oven.

Thank you.

Mary

Andrew

--
Andrew Flegg -- | http://www.bleb.org/

"Toby" wrote in message
...
Great! While it was coming on the screen I was composing orders of
superlatives. It was brilliant!

Then, when it had finished loading, it shrank to about half the screen
size
and looked just the same as before.

I wish I could show you! But I'm not complaining, my rubber bands

As it's just the image alone rather than in a web page, MS IE is being
'clever' and shrinking it to fit the window.
After it has loaded, wave the mouse somewhere else, then bring it back
over
the picture and an icon will overlay the bottom right corner. Click to get
it back full size.


OH!

I've just adjusted my image sizing - but that's a fascinating idea. Thank
you.

Mary
Toby.

"Dave Gibson" wrote in message
...

"Mary Fisher" wrote in message
t...



I've just adjusted my image sizing - but that's a fascinating idea.
Thank
you.

Mary

..... and finally, I've chucked a lump of HTML around it to define the
image
size.

Try http://nanohelix.tripod.com/ and see how you get on.

Well! That certainly worked - but is is because of the hi tech lump chucking
you've done or because I adjusted my image sizing?

Hmm. I'll go back to the original for a comparison.

By the way, it's many years since I've heard of old Max, ah happy days ...

Mary

Dave

Is there such an animal?

Yes, a surprising range for what is an infant industry.

snip

Try a Google search on [ LED white replacement MR16] or [ LED white
replacement GU10 ] for more details.

OK, will do. This has become more of a quest for the Holy Grail than a
simple curiosity!

The power consumption is about 2-5
watts per bulb and the light output appears to be equivalent to a 20W
incandescent. The makers quote 50,000 hours life, but a recent R4 news
item mentioned that 150,000 hours is more typical for an LED.

I thought I heard 25,000 but that would probably see me out!


Mary

A nasty looking dwarf throws a knife at you.

No problem, I'll catch it in my teeth.