Some papers that might be relevant to the effective brightness of strobed LEDs
mi...@sushi.com
<http://physics.nist.gov/Divisions/Div844/publications/ohno/
SPIE_SD97.pdf>
<http://www.periheliondesign.com/downloads/
aircraft_beacons_using_leds.pdf>
Jan Panteltje
"mi...@sushi.com" <mi...@sushi.com> wrote in
<ccdc8f76-b486-4a61...@n13g2000vbe.googlegroups.com>:
Interesting papers, lots of data...
mi...@sushi.com
> On a sunny day (Sun, 3 Jan 2010 21:55:18 -0800 (PST)) it happened
> <ccdc8f76-b486-4a61-a2bc-e05e23dce...@n13g2000vbe.googlegroups.com>:
>
> ><http://www.caa.co.uk/docs/33/2008_01.pdf>
> ><http://physics.nist.gov/Divisions/Div844/publications/ohno/
> >SPIE_SD97.pdf>
> ><http://www.periheliondesign.com/downloads/
> >aircraft_beacons_using_leds.pdf>
>
> Interesting papers, lots of data...
I found the differences between the Xenon stroble and LED operation
particular to anti-collision lighting interesting. The strobe is over
in microseconds, but the LED needs at least 100ms. Now we know that is
too long for one pulse, so some are PWMing the LED current.
I'd have to dig it up, but there was very little known about xenon
strobe lighting in aircraft at one point in time, so NASA did a survey
of the pulse data on units already on the market. Better late than
never I suppose.
I'm hoping one of the uber-geeks that knows all this eye related
theory will pronounce when scheme (DC or pulse) is better. It seems
the market certainly hasn't picked a winner.
Jan Panteltje
"mi...@sushi.com" <mi...@sushi.com> wrote in
<a6b104ab-765b-4a20...@22g2000yqr.googlegroups.com>:
Very long time ago I made a stroboscope flash that went on top of a building...
At that time I did some reseach into type of flashbulbs.
I have feedback it could be seen from miles aways :-)
LEDs for something like that would have a much higher lifetime I think.
mi...@sushi.com
> On a sunny day (Mon, 4 Jan 2010 14:48:47 -0800 (PST)) it happened
> <a6b104ab-765b-4a20-b7b8-e8fe1a949...@22g2000yqr.googlegroups.com>:
LEDs are also more rugged than a strobe. They are replacing strobes on
transmitter towers with LEDs. Less EMI as well. Both situations have
expensive replacement costs. From people I know with transmitter
sites, finding people that climb towers doesn't get any easier.
Robert Baer
> <http://www.caa.co.uk/docs/33/2008_01.pdf>
Pray tell what is this insanity and stupidity of "this page is
intentionally blank" (see pages 6, 8, and 10) that is seen "everywhere"?
John Devereux
> mi...@sushi.com wrote:
>> <http://www.caa.co.uk/docs/33/2008_01.pdf>
> Pray tell what is this insanity and stupidity of "this page is
> intentionally blank" (see pages 6, 8, and 10) that is seen
> "everywhere"?
Blank pages are inserted to improve the layout, for example so that new
chapters start on a right-hand page. But sometimes a blank page can
appear because the printer picked up two pages at once! How is a reader
to tell, they could miss vital information especially in a safety
document. So they print "This page left blank intentionally" or
somesuch.
My dad had a printing company. As a kid I often had the menial jobs, the
worst was "checking for blanks". This was the process of manually
flipping through printed pages, checking that each one had actually been
printed. The most common page in a document was in fact "This page left
blank intentionally". These were used in large numbers so it was more
efficient to print off a big batch, then use them as required when
assembling documents. I then had the exciting job of checking 5000
"TPLBI" sheets for blanks.
>
>> <http://physics.nist.gov/Divisions/Div844/publications/ohno/
>> SPIE_SD97.pdf>
>> <http://www.periheliondesign.com/downloads/
>> aircraft_beacons_using_leds.pdf>
--
John Devereux