Care And Feeding of LEDs and DC is Better Than Pulsed by HP

[Watson A.Name \"Watt Sun]

http://cp.literature.agilent.com/litweb/pdf/5988-9225EN.pdf

They suggest storing LEDs in mothballs to prevent the leads from
tarnishing. Other interesting tidbits.

http://cp.literature.agilent.com/litweb/pdf/5091-9704E.pdf

They say DC is better than pulsed operation for light output.

I originally set out to find the datasheets for some HPDL2416
alphanumeric displays. I got onto searchdatasheets.com and when I found
out that they asked to signup, I went thru the procedure. Then when I
finally got thru that, the b@stards asked for $50.00!! Those dirty SOBs
should've said up front that it was gonna cost money! And I'm really
gonna be po'd if they start sending junk mail or junk email to me using
the form I filled out! Idiots!

 

[Dave Platt]

Interesting. I have some very old LEDs - 20+ years - whose leads are
BLACK. Look just like Mom's sterling silver tea set when it hasn't been
polished for years. Every time I get in a pinch for an LED and have to
dive for one of the oldies (boy, their brightness sux!), I wonder what
the heck the leads are plated with.

Yup, they're almost certainly silver-plated. The black is probably a
combination of silver oxide and silver sulphide.

--
Dave Platt <dplatt@radagast.org> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Ken Taylor]

"Dave Platt" <dplatt@radagast.org> wrote in message
news:105jmgfot8rq15a@corp.supernews.com...

Interesting. I have some very old LEDs - 20+ years - whose leads are
BLACK. Look just like Mom's sterling silver tea set when it hasn't been
polished for years. Every time I get in a pinch for an LED and have to
dive for one of the oldies (boy, their brightness sux!), I wonder what
the heck the leads are plated with.

Yup, they're almost certainly silver-plated. The black is probably a
combination of silver oxide and silver sulphide.

--
Dave Platt <dplatt@radagast.org> AE6EO

One day we'll see a spruiker on a late-night infomercial showing us how to
use 'LED-OFF' to clean the leads of our old LED's......

Ken

 

[Hal Murray]

[context is lead wires on LEDs]

Yup, they're almost certainly silver-plated. The black is probably a
combination of silver oxide and silver sulphide.

Why would the leads on LEDs be silver plated? There must be some
interesting reason. Aside from the expense, it adds complications
like the corossing discussed here.

--
The suespammers.org mail server is located in California. So are all my
other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited
commercial e-mail to my suespammers.org address or any of my other addresses.
These are my opinions, not necessarily my employer's. I hate spam.

 

[Tim Wescott]

"Watson A.Name "Watt Sun - the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:c3acc2$6c8gp$1@hades.csu.net...

http://cp.literature.agilent.com/litweb/pdf/5988-9225EN.pdf

They suggest storing LEDs in mothballs to prevent the leads from
tarnishing. Other interesting tidbits.

http://cp.literature.agilent.com/litweb/pdf/5091-9704E.pdf

They say DC is better than pulsed operation for light output.

I originally set out to find the datasheets for some HPDL2416
alphanumeric displays. I got onto searchdatasheets.com and when I found
out that they asked to signup, I went thru the procedure. Then when I
finally got thru that, the b@stards asked for $50.00!! Those dirty SOBs
should've said up front that it was gonna cost money! And I'm really
gonna be po'd if they start sending junk mail or junk email to me using
the form I filled out! Idiots!

Agilent says the HDLG-2416 is pin-for-pin compatible with the "HPDL-2416".
Might be useful info depending on what you need to know.

Wonder if the obsoleted it for age, or because it said "HP" in it.

 

[Watson A.Name - \"Watt Su]

"Tim Wescott" <tim@wescottnospamdesign.com> wrote in message
news:105mbdd35qju8f5@corp.supernews.com...

"Watson A.Name "Watt Sun - the Dark Remover"" <NOSPAM@dslextreme.com
wrote
in message news:c3acc2$6c8gp$1@hades.csu.net...
http://cp.literature.agilent.com/litweb/pdf/5988-9225EN.pdf

They suggest storing LEDs in mothballs to prevent the leads from
tarnishing. Other interesting tidbits.

http://cp.literature.agilent.com/litweb/pdf/5091-9704E.pdf

They say DC is better than pulsed operation for light output.

I originally set out to find the datasheets for some HPDL2416
alphanumeric displays. I got onto searchdatasheets.com and when I
found
out that they asked to signup, I went thru the procedure. Then when
I
finally got thru that, the b@stards asked for $50.00!! Those dirty
SOBs
should've said up front that it was gonna cost money! And I'm
really
gonna be po'd if they start sending junk mail or junk email to me
using
the form I filled out! Idiots!

Agilent says the HDLG-2416 is pin-for-pin compatible with the
"HPDL-2416".
Might be useful info depending on what you need to know.

Wonder if the obsoleted it for age, or because it said "HP" in it.

Thanks for the info. All I need is the pinout so I can connect them up.
I think I'll be able to salvage a half dozen or more of them.

 

In sci.electronics.misc "Watson A.Name \"Watt Sun - the Dark Remover\"" <NOSPAM@dslextreme.com> wrote:
| http://cp.literature.agilent.com/litweb/pdf/5988-9225EN.pdf
|
| They suggest storing LEDs in mothballs to prevent the leads from
| tarnishing. Other interesting tidbits.
|
| http://cp.literature.agilent.com/litweb/pdf/5091-9704E.pdf
|
| They say DC is better than pulsed operation for light output.
|
| I originally set out to find the datasheets for some HPDL2416
| alphanumeric displays. I got onto searchdatasheets.com and when I found
| out that they asked to signup, I went thru the procedure. Then when I
| finally got thru that, the b@stards asked for $50.00!! Those dirty SOBs
| should've said up front that it was gonna cost money! And I'm really
| gonna be po'd if they start sending junk mail or junk email to me using
| the form I filled out! Idiots!

There ought to be a law against that practice. There might be now.
It's called truth in pricing. The information asked for is the first
cost. Then they tack on another $50.

This is why when I see forms wanting information to sign up to get what
is being offered, which I don't know for sure that I will get, yet, I
always do a "dry run" filling in bogus information to test out the process
and see where it goes. Sometimes it's a compatibility issue.

I would say DC is better for LEDs, too. But I'm biased; I can see the 120
Hz flicker (I'd be even more upset if I was in 50 Hz land since then it
would be 100 Hz flicker). This is why I don't use fluorescent when I can
avoid it (which is usually). I plan to use DC even for incandescent lights.

--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------

 

[Fleetie]

I would say DC is better for LEDs, too. But I'm biased; I can see the 120
Hz flicker (I'd be even more upset if I was in 50 Hz land since then it
would be 100 Hz flicker). This is why I don't use fluorescent when I can
avoid it (which is usually). I plan to use DC even for incandescent
lights.

It bugs me too. I have always been able to "see" pretty damn high
frequency flashing of LEDs and similar; at least a few kHz. Also,
I can determine the approximate duty cycle of say, streetlights
(they go dark as the voltage crosses zero, obviously) or other
rapidly flashing small lights.

I do it by very rapidly darting my eyeballs up and down, so the
light under scrutiny leaves a long "trace" line on my retina, and
persistence of vision takes care of the rest, so I can estimate
both the frequency and the duty cycle.

I've done this since being a child, well, a young teenager anyway,
and I remember setting up a 555 or something and an LED and asking
my parents whether they could detect it flashing, and they said
they couldn't! I felt I was da daddy, man!

Anyone else do this regularly. I think it's a cool technique!


Martin - in "50Hz Land"
--
M.A.Poyser Tel.: 07967
110890
Manchester, U.K.
http://www.fleetie.demon.co.uk

 

[Roger Gt]

"Fleetie" wrote

: > I would say DC is better for LEDs, too.

Yet most of the LEDs are specified for this service! Almost all
displays are multiplexed and I have been building them this way
for at least three decades! Never had a "flicker" complaint, but
I pulse the LEDs in 0.5 millisecond clicks! See that do you?
(2KHZ)

<snip>
: It bugs me too. I have always been able to "see" pretty damn
high
: frequency flashing of LEDs and similar; at least a few kHz.

The Human eye can not follow an on off change at faster than about
20HZ, are you saying your NOT human?

: Also,
: I can determine the approximate duty cycle of say, streetlights
: (they go dark as the voltage crosses zero, obviously) or other
: rapidly flashing small lights.

Incandescent to NOT go dark with AC. The thermal TC is over a
Half cycle and the light variation is not great.

: I do it by very rapidly darting my eyeballs up and down, so the
: light under scrutiny leaves a long "trace" line on my retina,
and
: persistence of vision takes care of the rest, so I can estimate
: both the frequency and the duty cycle.

Cheap trick. You can not "really" see the flicker at all. Your
creating the flicker by rapidly shifting your view, thereby
'strobing' the view at a much lower rate. Can't watch TV or a
Movie can you? They all flicker since the HUMAN EYE can not
follow such rapid changes.

: Anyone else do this regularly. I think it's a cool technique!

Why would anyone WANT to do it?

: Martin - in "50Hz Land"
: --
: M.A.Poyser
Tel.: 07967
: 110890
: Manchester, U.K.
: http://www.fleetie.demon.co.uk

Oh! That explains it!

 

In sci.electronics.misc Roger Gt <not@here.net> wrote:
| "Fleetie" wrote
|
| : > I would say DC is better for LEDs, too.
|
| Yet most of the LEDs are specified for this service! Almost all
| displays are multiplexed and I have been building them this way
| for at least three decades! Never had a "flicker" complaint, but
| I pulse the LEDs in 0.5 millisecond clicks! See that do you?
| (2KHZ)
|
| <snip>
| : It bugs me too. I have always been able to "see" pretty damn
| high
| : frequency flashing of LEDs and similar; at least a few kHz.
|
| The Human eye can not follow an on off change at faster than about
| 20HZ, are you saying your NOT human?

There's a difference between "follow" and "be affected by". I would
not say I can follow the 120 Hz flicker of florescent lighting, but
I do know it causes me, and many other people I know, problems from
stress to headaches. 120 Hz flicker in LEDs wouldn't be any different.

But much higher than that, and mechanical vibrations due to EM fields
would be an acoustical problem. Beyond that range and you start to
lose power in the system to EMF radiation.

DC just makes life simple.


| : Also,
| : I can determine the approximate duty cycle of say, streetlights
| : (they go dark as the voltage crosses zero, obviously) or other
| : rapidly flashing small lights.
|
| Incandescent to NOT go dark with AC. The thermal TC is over a
| Half cycle and the light variation is not great.

Incandescent decreases slightly, but not by much. It generally
does not bother me.


| : I do it by very rapidly darting my eyeballs up and down, so the
| : light under scrutiny leaves a long "trace" line on my retina,
| and
| : persistence of vision takes care of the rest, so I can estimate
| : both the frequency and the duty cycle.
|
| Cheap trick. You can not "really" see the flicker at all. Your
| creating the flicker by rapidly shifting your view, thereby
| 'strobing' the view at a much lower rate. Can't watch TV or a
| Movie can you? They all flicker since the HUMAN EYE can not
| follow such rapid changes.

I can "analyze" the flicker by rapid eye movements. That's how I can
see problems with lights like florescent. For example I can see that
florescent changes color during the cycle by moving my eyes. When
I don't move my eyes, I merely get a headache after 2-3 hours of it.


| : Anyone else do this regularly. I think it's a cool technique!
|
| Why would anyone WANT to do it?

I would take DC to eliminate flicker so I can use LEDs. I do plan to include
a DC circuit system in the house I am building. At least LEDs would run from
it. Whether I would put incandescent on it, too, I don't know. But if I am
going to do most of the lighting with it, it won't be 12 volts.

--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------

 

[Fleetie]

"Roger Gt" <not@here.net> farted thus:

"Fleetie" wrote
snip
: It bugs me too. I have always been able to "see" pretty damn
high
: frequency flashing of LEDs and similar; at least a few kHz.

The Human eye can not follow an on off change at faster than about
20HZ, are you saying your NOT human?

No, you need to read again what I wrote. I described the method
by which I can detect it further down my post. And it's
"...you're not human"; you could have done with paying more
attention in class, or do you have learning difficulties? (In which
case I apologise.)

: Also,
: I can determine the approximate duty cycle of say, streetlights
: (they go dark as the voltage crosses zero, obviously) or other
: rapidly flashing small lights.

Incandescent to NOT go dark with AC. The thermal TC is over a
Half cycle and the light variation is not great.

I said "streetlights", dorkmeister. When was the last time you
saw an incandescent streetlight? Huh-huh!

Cheap trick. You can not "really" see the flicker at all. Your
creating the flicker by rapidly shifting your view, thereby
'strobing' the view at a much lower rate. Can't watch TV or a
Movie can you? They all flicker since the HUMAN EYE can not
follow such rapid changes.

Get laid, for fuck's sake, then you might be less eager to jump
down people's throats, accusing them of saying things that they
never said, which if only you'd read the messages properly, you'd
have known.

If you can't get laid, at least have a wank and do the rest of us
a favour!


Martin
--
M.A.Poyser Tel.: 07967
110890
Manchester, U.K.
http://www.fleetie.demon.co.uk

 

[Roger Gt]

X-No-Archive: yes
"Fleetie" wrote
: "Roger Gt" wrote
: > "Fleetie" wrote
: > <snip>
: > : It bugs me too. I have always been able to "see" pretty damn
: > : high frequency flashing of LEDs and similar; at least a few
kHz.
: >
: > The Human eye can not follow an on off change at faster than
about
: > 20HZ, are you saying your NOT human?
:
: No, you need to read again what I wrote. I described the method
<Poor response deleted>

: > : Also,
: > : I can determine the approximate duty cycle of say,
streetlights
: > : (they go dark as the voltage crosses zero, obviously) or
other
: > : rapidly flashing small lights.
: >
: > Incandescent to NOT go dark with AC. The thermal TC is over a
: > Half cycle and the light variation is not great.
:
: <Poor response deleted> When was the last time you
: saw an incandescent streetlight? Huh-huh!

Last night!

: > Cheap trick. You can not "really" see the flicker at all.
Your
: > creating the flicker by rapidly shifting your view, thereby
: > 'strobing' the view at a much lower rate. Can't watch TV or a
: > Movie can you? They all flicker since the HUMAN EYE can not
: > follow such rapid changes.
:
: <Poor response deleted> then you might be less eager to jump
: down people's throats, accusing them of saying things that they
: never said, which if only you'd read the messages properly,
you'd
: have known.
:
: <Poor response deleted>

:
: Martin
: --
: M.A.Poyser
Tel.: 07967
: 110890
: Manchester, U.K.
: http://www.fleetie.demon.co.uk

Bad language indicated you lack of proper manners.

PLONK

--
Anybody can become angry - that is easy, but to be angry with the
right person and to the right degree and at the right time and for
the right purpose, and in the right way - that is not within
everybody's power and is not easy.
Aristotle

:

 

[Mark Rejhon]

Hi,

The Human eye can not follow an on off change at faster than about
20HZ, are you saying your NOT human?

Actually, it varies from human to human. A very few can see
fluorescent light flicker get annoyed by fluorescent lamp flicker (my
mother was diagnosed with sensitivity to fluorescent lamp flicker).
An even larger number of people can notice the flicker on some
monitors less than 75 Hz is often seen with flicker. Not everybody
can, but there are several. There is a law of diminishing returns.

Also, the brighter the light, the easier it is to detect flicker --
it's easier to see flicker on a computer monitor set to low refresh
rates (50-60 Hz) when bright lights are on than off. However, it is
frequently easy to notice TV flicker when you turn on office
fluorescent lighting or the room is surrounded on 2-3 sides with at
least one south/east window on a very sunny day, with all drapes fully
open.

Also, flicker is easier to notice in peripheral vision than staring
directly, so if you stare at a nearby object such as your keyboard,
you may notice monitor flicker from the edge of your view. (Try
doing this with bright lights turned on, and Refresh Rate set down to
only 60 Hz). Other people are sensitive enough that flicker is very
blatantly noticeable. Most people watch TV's in dimmed light or
incandescent light, so they are not affected.

Incidentially, the off duty cycle between flicker also matters, so
flicker in a 60 Hz strobe light (Off 99%+ of the time between
flickers) is easier to see than 60 hz flicker in an uncapacitor'd LED
connected to AC power. In other cases, flicker is not noticed except
"felt" as eyestrain.

Most people attempting to watch CRT television outdoors on a sunny day
(with the Brightness control pumped to the maximum, on bright TV's
such as Sony Trinitron tubes), actually have noticed 50 Hz flicker
very easily, and 60 Hz flicker to a lesser extent. Obviously, not
many watches TV outdoors except RV travellers and electricified
campsites and such, but it's pretty obvious whenever the sun is
shining directly on the TV watching environment area.

While the flicker threshold varies from person to person, the
following is true for virtually everyone, regardless of flicker
threshold:

Factors that amplify flicker sensation:
- Brighter environmental light (i.e. office fluorescent, sunlight,
etc)
- Brighter flickering light source
- Using peripheral vision
- Longer dark duty cycle and shorter bright duty cycle (i.e.
strobelight style)

Factors that subdue flicker sensation:
- Darker environment
- Dimmer flickering light source
- Staring directly
- Shorter dark duty cycles and longer bright duty cycles

Because of these factors, there are cases where the flicker threshold
is very very low for the same person (like 20 Hz) for a direct stare,
while other cases, the flicker threshold is very very high for the
same person (like 60 Hz) for a direct stare.

One very good case study where it really matters: It is true that
moving eyes around is a factor that amplifies flicker sensation. Even
moving eyes slowly (during a movie panning scene), can amplify flicker
sensation. This is why some people get rainbow-flicker fatigue on
some DLP projectors that modulate pixels at hundreds of hertz, just do
a search at http://www.avsforum.com Home Theater Forum (Internet's
Biggest) using search term "DLP rainbows". You'll find some hits on
older DLP's (especially if you limit your search range to year 2001
and older) with slower 2X spinning colorwheels which would represent
360 Hz cycling, where dozens of people have actually returned their
DLP's to the store due to this lower frequency, before Texas
Instruments introduced the 6X colorwheels for the DLP home theater
projectors. The flicker is in a colorwheel cycle
red-green-blue-red-green-blue-red-green-blue and there are some people
who can't watch a movie even when the colorwheel frequency is 2X (60
Hz x 3 colors x 2 speed = 360 Hz cycling). For this reason, Texas
Instruments ramped up the colorwheel speeds, and now today, even
today's $899 conference room DLP projectors [www.dell.com] now use
higher-frequency color wheels.

Anyhow.... Please refer to numerous scientific studies over the years
that has countless covered these factors many times over...

Thanks,
Mark Rejhon

 

[Mark Rejhon]

Addendum...

What I said:

http://www.avsforum.com Home Theater Forum (Internet's
Biggest) using search term "DLP rainbows". You'll find some hits
on older DLP's (especially if you limit your search range to year 2001
and older)

Actually, http://archive.avsforum.com holds the older posts
(go to the Search link in there), although the main site contains
hundreds of Search hits for "DLP rainbows"

Here's a very old program I wrote back around 1993 or thereabouts:
QuickBASIC 4.5 source code included.
http://www.marky.com/files/dos/motion.zip

This simple program flickers an object on your computer screen.
Almost everybody can immediately notice the flicker in the 30 Hz
object in this program.
Also famous is http://www.marky.com/files/dos/motion.zip
which demonstrates a clear fluidness difference between
30fps versus 60fps.

Both programs still manage to run under Windows XP
(via its dos box window). Both programs use the VGA
port number 0x03DA vertical retrace interval register
to synchronize the flashing/motion to the vertical
refresh rate of the good old 320x200 VGA mode

And hey, these programs were written 10 years ago,
as "see-for-yourself" demos to disprove people like you
who say "people can't tell flicker in 20 Hz"
and "people can't tell 30fps apart from 60fps".

There were tens of thousands of hits from a 3D gaming
website back in about 1997 or thereabouts (I think it
was Operation 3.D.F.X. or something) when there was
still a lot of controversy back then about whether
30fps versus 60fps made a difference...

It's a dead horse now.

Thanks,
Mark Rejhon
www.marky.com <-- since 1996

 

[Roger Gt]

"Mark Rejhon" <spamguard@marky.com> wrote in message
news:323f419b.0403232132.149c9ab1@posting.google.com...
: Addendum...
:
: What I said:
: >http://www.avsforum.com Home Theater Forum (Internet's
: >Biggest) using search term "DLP rainbows". You'll find some
hits
: >on older DLP's (especially if you limit your search range to
year 2001
: >and older)
:
: Actually, http://archive.avsforum.com holds the older posts
: (go to the Search link in there), although the main site
contains
: hundreds of Search hits for "DLP rainbows"
:
: Here's a very old program I wrote back around 1993 or
thereabouts:
: QuickBASIC 4.5 source code included.
: http://www.marky.com/files/dos/motion.zip
:
: This simple program flickers an object on your computer screen.
: Almost everybody can immediately notice the flicker in the 30 Hz
: object in this program.
: Also famous is http://www.marky.com/files/dos/motion.zip
: which demonstrates a clear fluidness difference between
: 30fps versus 60fps.
:
: Both programs still manage to run under Windows XP
: (via its dos box window). Both programs use the VGA
: port number 0x03DA vertical retrace interval register
: to synchronize the flashing/motion to the vertical
: refresh rate of the good old 320x200 VGA mode
:
: And hey, these programs were written 10 years ago,
: as "see-for-yourself" demos to disprove people like you
: who say "people can't tell flicker in 20 Hz"
: and "people can't tell 30fps apart from 60fps".
:
: There were tens of thousands of hits from a 3D gaming
: website back in about 1997 or thereabouts (I think it
: was Operation 3.D.F.X. or something) when there was
: still a lot of controversy back then about whether
: 30fps versus 60fps made a difference...
:
: It's a dead horse now.
:
: Thanks,
: Mark Rejhon
: www.marky.com <-- since 1996


Thanks for your Ernest effort. However I have over the years
designed displays for a variety of uses and the normal movie flip
rate is 24 HZ... My CRT on this system is running at 70HZ and
since the phosphor holds the image for a bit there is almost no
flicker. I just ran my interrupter strobe to check.. The TV
updates at 30HZ. (NTSC) and there is a barely detectable flicker
with the Strobe.....

Since some of my work was on Military heads up displays we had
doctors come in and give classes on acceptable rates and effects
of various update frequencies. You can put some one to sleep with
the "right" frequency.... Not what you what with a pilot... Or a
weapons operator.

I'll stick with what I have tested and know works....

 

[Watson A.Name \"Watt Sun]

Roger Gt wrote:

"Mark Rejhon" <spamguard@marky.com> wrote in message
news:323f419b.0403232132.149c9ab1@posting.google.com...
: Addendum...

: What I said:
: >http://www.avsforum.com Home Theater Forum (Internet's
: >Biggest) using search term "DLP rainbows". You'll find some
hits
: >on older DLP's (especially if you limit your search range to
year 2001
: >and older)

: Actually, http://archive.avsforum.com holds the older posts
: (go to the Search link in there), although the main site
contains
: hundreds of Search hits for "DLP rainbows"

: Here's a very old program I wrote back around 1993 or
thereabouts:
: QuickBASIC 4.5 source code included.
: http://www.marky.com/files/dos/motion.zip

: This simple program flickers an object on your computer screen.
: Almost everybody can immediately notice the flicker in the 30 Hz
: object in this program.
: Also famous is http://www.marky.com/files/dos/motion.zip
: which demonstrates a clear fluidness difference between
: 30fps versus 60fps.

: Both programs still manage to run under Windows XP
: (via its dos box window). Both programs use the VGA
: port number 0x03DA vertical retrace interval register
: to synchronize the flashing/motion to the vertical
: refresh rate of the good old 320x200 VGA mode

: And hey, these programs were written 10 years ago,
: as "see-for-yourself" demos to disprove people like you
: who say "people can't tell flicker in 20 Hz"
: and "people can't tell 30fps apart from 60fps".

: There were tens of thousands of hits from a 3D gaming
: website back in about 1997 or thereabouts (I think it
: was Operation 3.D.F.X. or something) when there was
: still a lot of controversy back then about whether
: 30fps versus 60fps made a difference...

: It's a dead horse now.

: Thanks,
: Mark Rejhon
: www.marky.com <-- since 1996

Thanks for your Ernest effort. However I have over the years
designed displays for a variety of uses and the normal movie flip
rate is 24 HZ... My CRT on this system is running at 70HZ and
since the phosphor holds the image for a bit there is almost no
flicker. I just ran my interrupter strobe to check.. The TV
updates at 30HZ. (NTSC) and there is a barely detectable flicker
with the Strobe.....

The TV updates each field (which has every other line of the frame)
every 1/60th of a second, and every 1/30th of a second it updates the
whole frame. That's interlacing. Read about it here, skip down to
"The Benefits of.."0
http://www.panasonic.com/consumer_electronics/dvd_players/progscan.asp

[snip]

 

[Roger Gt]

"Watson A.Name "Watt Sun - the Dark Remover""
<NOSPAM@dslextreme.com> wrote in message
news:c3sfb4$6etar$1@hades.csu.net...
: Roger Gt wrote:
: > "Mark Rejhon" <spamguard@marky.com> wrote in message
: > news:323f419b.0403232132.149c9ab1@posting.google.com...
: > : Addendum...
:
<snip>
: > Thanks for your Ernest effort. However I have over the years
: > designed displays for a variety of uses and the normal movie
flip
: > rate is 24 HZ... My CRT on this system is running at 70HZ and
: > since the phosphor holds the image for a bit there is almost
no
: > flicker. I just ran my interrupter strobe to check.. The TV
: > updates at 30HZ. (NTSC) and there is a barely detectable
flicker
: > with the Strobe.....
:
: The TV updates each field (which has every other line of the
frame)
: every 1/60th of a second, and every 1/30th of a second it
updates the
: whole frame. That's interlacing. Read about it here, skip down
to
: "The Benefits of.."0
:
http://www.panasonic.com/consumer_electronics/dvd_players/progscan.asp
:
: [snip]


Thanks, I guess......
Sorry I omitted a detail, I REALLY thought since I specified the
(NTSC) it would be clear.
I have only designed displays since 1963, so I could use a LOT of
help.... I'm sure!

 

[Don Klipstein]

In art. <Cdb8c.42024$JG2.16804@newssvr25.news.prodigy.com>, Roger Gt wrote:

Thanks for your Ernest effort. However I have over the years
designed displays for a variety of uses and the normal movie flip
rate is 24 HZ...

And the screen is illuminated something like 85% of the time. And, the
way I hear it, movie projectors add an extra interruption of the light in
the middle of showing a frame so that the flicker rate is 48 Hz. That's
roughly 17.8 milliseconds on, 3 milliseconds off.

Most CRTs have the phosphor fade quite a bit within a millisecond, so
they would have flicker that is usually noticeable if they used 48 Hz.

My CRT on this system is running at 70HZ and
since the phosphor holds the image for a bit there is almost no
flicker. I just ran my interrupter strobe to check.. The TV
updates at 30HZ. (NTSC) and there is a barely detectable flicker
with the Strobe.....

NTSC TV sets are interlaced and the vertical scan rate is 60 Hz. If I
look at one with a strong magnifier so that individual horizontal lines
really stand out, I see the lines flickering.

- Don Klipstein (don@misty.com)

 

[R.Lewis]

"Don Klipstein" <don@manx.misty.com> wrote in message
news:slrnc646a6.qen.don@manx.misty.com...

In art. <Cdb8c.42024$JG2.16804@newssvr25.news.prodigy.com>, Roger Gt
wrote:

Thanks for your Ernest effort. However I have over the years
designed displays for a variety of uses and the normal movie flip
rate is 24 HZ...

And the screen is illuminated something like 85% of the time. And, the
way I hear it, movie projectors add an extra interruption of the light in
the middle of showing a frame so that the flicker rate is 48 Hz. That's
roughly 17.8 milliseconds on, 3 milliseconds off.

Most CRTs have the phosphor fade quite a bit within a millisecond, so
they would have flicker that is usually noticeable if they used 48 Hz.

My CRT on this system is running at 70HZ and
since the phosphor holds the image for a bit there is almost no
flicker. I just ran my interrupter strobe to check.. The TV
updates at 30HZ. (NTSC) and there is a barely detectable flicker
with the Strobe.....

NTSC TV sets are interlaced and the vertical scan rate is 60 Hz. If I
look at one with a strong magnifier so that individual horizontal lines
really stand out, I see the lines flickering.

- Don Klipstein (don@misty.com)

take a look at the research and follow the references through if you have a
mind to.

http://www.unice.fr/LPEQ/pagesperso/thierry/Publications/abstract%20VR.htm

 

[Mark Rejhon]

Thanks for your Ernest effort. However I have over the years
designed displays for a variety of uses and the normal movie flip
rate is 24 HZ... My CRT on this system is running at 70HZ and
since the phosphor holds the image for a bit there is almost no
flicker. I just ran my interrupter strobe to check.. The TV
updates at 30HZ. (NTSC) and there is a barely detectable flicker
with the Strobe.....

Actually, the TV updates at 60 Hz -- alternating scanlines.
It's interlaced. Even scanlines are displayed, then
odd scanlines are displayed.

Since your strobe meter only measures one point of the screen,
it will measure only 30 Hz. If your strobe meter is on a point
of the TV measuring an even scanlines, it won't measure the
flicker caused by the odd scanlines. These are usually
called 'fields'.

There are actually 60 distinct images per second from NTSC TV
and 50 distinct images per second from a PAL TV.

Football and other fast-motion shows take advantage of the
fact that 60 images per second (half vertical resolution though)
and that is why, with a line doubler, you see things like
"interlace" artifacts when you try to convert to progressive scan:
Screenshot Example of Interlace Artifacts
http://www.dscaler.org/screenshots/index.htm
(3:2 pulldown were 24 Hz film is encoded in 60 Hz interlaced video)

As you can see from those interlace artifacts, there can be
two different images in one frame of television. Normally,
on interlaced displays, this is good, because it maximizes
the temporal resolution to 60 Hz. If you analyze a videocaptured
version of NTSC or PAL football in fast motion, you will see
50 SEPARATE or 60 SEPARATE images! (Make sure you use
video capture software capable of editing on a per-field
basis, not per-frame basis).

If the TV was 30 Hz progressive scan, you WILL see the flicker,
it will look like the flicker in the 30fps square at
http://www.marky.com/files/dos/flicker.zip

Since some of my work was on Military heads up displays we had
doctors come in and give classes on acceptable rates and effects
of various update frequencies. You can put some one to sleep with
the "right" frequency.... Not what you what with a pilot... Or a
weapons operator.

I'll stick with what I have tested and know works....

There is no conflict. All NTSC and PAL systems does
60 fields per second (and thus, 60 images per second)

By the way, computer graphics connected to NTSC/PAL
compatible displays, as is common with many legacy
computer systems (not just home systems, but does
include Commodore 64, Apple, etc), outputs 60
distinct images per second in the respective fields,
not 30 static frames per second. That means, the
even scanlines and oddscanlines are different images,
taking advantage of the fact that the opposite scanlines
are displayed 1/60th second apart (1/50th if PAL), giving
a temporal resolution of 60 images per second (50 for PAL)

If the vertical resolution is close to 240 or 288
rather than 480 or 512 or 525 (or similiar), usually
the interlaced fields are overlapped instead of
offset, to eliminate the interlacing (those "moving scanlines"
you notice when you walk up to a TV set and stare closely,
but are stationary if you connect the NTSC output
of a legacy computer system.

Strobe meter against the display will typically not work,
since it will usually capture only one of the two fields.
But if you run a strobe meter in an 'averaging' mode
at a distance away from the display, you will measure
the full field rate (50 or 60 respectively) rather
than the framerate.

The important thing to remember is that frames on
interlaced displays, typically contain two fields,
and the two fields can be completely different images.

Thanks,
Mark Rejhon
http://www.marky.com