Advice needed: CRT monitor 'flicker' problem caused by nea..

An LCD is about the only workable solution.

--
DaveW



"Sodah" <sodah6.RemoveThis@home.com> wrote in message
news:X4N0c.661124$X%5.80923@pd7tw2no...
 > Hi!
 > I just moved into my sisters place, which is adjacent to some high-tension
 > power-lines. Set up my computer yesterday, and immediately observed a
fine
 > but pervasive 'flicker' on my (CRT) monitor (similar to what my sister has
 > been experiencing with her own two [CRT] computer monitors for years).
This
 > is quite annoying, not to mention rapidly productive of eyestrain and
 > fatigue. Based on my own monitor's past performance, coupled with my
 > sister's consistent experience with her own monitors, it seems obvious to
me
 > that this 'flicker' is due entirely to electromagnetic-interference from
the
 > power lines. What I would like to know, if anybody out there can tell me,
 > is: (1) Might there be any conceivable action I could take to better
shield
 > my monitor from such electromagnetic interference (e.g. a commercial
add-on
 > product, or home-made metallic shroud, etc...)? ; (2) Please correct me
if
 > I am not right in my guess that (failing the above) replacing my CRT
monitor
 > with an LCD monitor should avoid the problem (i.e. since the latter does
not
 > utilize an electromagnetically-hypersensitive electron beam).
 >
 > Thanks in advance for any helpful advice, experience, links to info,
etc...
 >
 > Sodah
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

Yes, it does appear to move more so vertically than horizontally. And yes
again ... I have tried all refresh rates my monitor can handle (up to 140
Mhz), but to no avail.

Sodah


"Eric Gisin" <ericgisin RemoveThis @graffiti.net> wrote in message
news:c20ake11nh8@enews2.newsguy.com...
 > It is magnetic interference. Does it move vertically? Did you try refresh
 > rates of 60 and the highest your monitor can handle?
 >
 > "Sodah" <sodah6 RemoveThis @home.com> wrote in message
 > news:X4N0c.661124$X%5.80923@pd7tw2no...
  > > Hi!
  > > I just moved into my sisters place, which is adjacent to some
high-tension
  > > power-lines. Set up my computer yesterday, and immediately observed a
fine
  > > but pervasive 'flicker' on my (CRT) monitor (similar to what my sister
has
  > > been experiencing with her own two [CRT] computer monitors for years).
This
  > > is quite annoying, not to mention rapidly productive of eyestrain and
  > > fatigue. Based on my own monitor's past performance, coupled with my
  > > sister's consistent experience with her own monitors, it seems obvious
to me
  > > that this 'flicker' is due entirely to electromagnetic-interference from
the
  > > power lines. What I would like to know, if anybody out there can tell
me,
  > > is: (1) Might there be any conceivable action I could take to better
shield
  > > my monitor from such electromagnetic interference (e.g. a commercial
add-on
  > > product, or home-made metallic shroud, etc...)? ; (2) Please correct me
if
  > > I am not right in my guess that (failing the above) replacing my CRT
monitor
  > > with an LCD monitor should avoid the problem (i.e. since the latter does
not
  > > utilize an electromagnetically-hypersensitive electron beam).
  > >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

Just to add an interesting footnote... Late evening/night (e.g. the present
moment) the 'flicker' diminishes _dramatically_. My guess is that this is
due to it being "off peak" hours for electricity demand (i.e. less energy
going through --and therefore, being emitted by-- the powerlines).


"DaveW" <none DeleteThis @zero.org> wrote in message
news:hmQ0c.160011$uV3.707652@attbi_s51...
 > An LCD is about the only workable solution.
 >
 > --
 > DaveW
 >

Thought so. But I love my CRT monitor! So... before I decide to
throw-in-the-towel and "downgrade" to an LCD (just my personal
preference/opinion), I'm going to put just a little more time into looking
for some way to "magnetically shield" my monitor (i.e. the space it is in).
To anyone out there technically versed in such stuff (i.e. "magnetic
shielding"), I'd eagerly welcome any useful information/insight/etc. you
might be able to share towards this.

Thanks,

Sodah


 >
 >
 > "Sodah" <sodah6 DeleteThis @home.com> wrote in message
 > news:X4N0c.661124$X%5.80923@pd7tw2no...
  > > Hi!
  > > I just moved into my sisters place, which is adjacent to some
high-tension
  > > power-lines. Set up my computer yesterday, and immediately observed a
 > fine
  > > but pervasive 'flicker' on my (CRT) monitor (similar to what my sister
has
  > > been experiencing with her own two [CRT] computer monitors for years).
 > This
  > > is quite annoying, not to mention rapidly productive of eyestrain and
  > > fatigue. Based on my own monitor's past performance, coupled with my
  > > sister's consistent experience with her own monitors, it seems obvious
to
 > me
  > > that this 'flicker' is due entirely to electromagnetic-interference from
 > the
  > > power lines. What I would like to know, if anybody out there can tell
me,
  > > is: (1) Might there be any conceivable action I could take to better
 > shield
  > > my monitor from such electromagnetic interference (e.g. a commercial
 > add-on
  > > product, or home-made metallic shroud, etc...)? ; (2) Please correct me
 > if
  > > I am not right in my guess that (failing the above) replacing my CRT
 > monitor
  > > with an LCD monitor should avoid the problem (i.e. since the latter does
 > not
  > > utilize an electromagnetically-hypersensitive electron beam).
  > >
  > > Thanks in advance for any helpful advice, experience, links to info,
 > etc...
  > >
  > > Sodah
  > >
  > >
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

"Sodah" <sodah6.DeleteThis@home.com> wrote in message
news:goX0c.646438$JQ1.309669@pd7tw1no...
 > Just to add an interesting footnote... Late evening/night (e.g. the
present
 > moment) the 'flicker' diminishes _dramatically_. My guess is that this is
 > due to it being "off peak" hours for electricity demand (i.e. less energy
 > going through --and therefore, being emitted by-- the powerlines).
Do a search on Google for mu metal . It works. It is VERY expensive
(around $300 for a monitor). You can probably do some good by changing the
location of the monitor. You would be surprised at what a few feet can do.
The strength of the field drops by the distance squared, so a small change
in the distance from the source can make a huge difference in the strength
of the field.

Also, assuming you are in a 60hz power location, change the scan rate of the
monitor (if possible). This often helps.

Charles Perry P.E.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

Did you try to increase the scan rate to about 80 Hz or something like this?

Are you located right under the power lines, or within a few hundred feet?

If the flicker is from the magnetic field of the power lines, you are
correct in assuming that the flicker will vary at particular times of the
day. This is correct in assuming that this has to do with the peak loading.

Your monitor CRT is shielded by a u-metal ( mew-metal ) shied according to
the international safety standards. This is to meet specific requirements.
Any type of magnetic field that can pass through in any direction would be
considered excessively strong, or the shield in your monitor is not adequate
according to established standards.

If you want to add shielding, the required type of metal is very expensive,
and the design of the shield set-up would be complex. To shield out the
lower frequencies, such as the 50 and 60 Hz from AC power sources is more
complicated than to shield out high frequencies such as X-Ray and microwave.

My suggestion is that if you are living in a condition where the field is so
strong to cause a monitor to flicker, you should strongly consider moving!
These fields are known to be dangerous over time. The power companies are in
denial about this, because there are not many long term studies, and many
that have been done were not openly published.


I would think your problem may be more serious than just a monitor
condition, if this is the case. I even have thoughts about the electrical
wiring in my home, even though it is of the average, and the fields from it
are very small. But, they are present, or I would not be able to have power
in my home.

Effect Of Electro Magnetic Fields (ELF) on humans, World Health Organization
<a style='text-decoration: underline;' href="http://www.who.int/peh-emf/about/WhatisEMF/en/index1.html" target="_blank">http://www.who.int/peh-emf/about/WhatisEMF/en/index1.html</a>

Power Line, Electro Magnetic Field (ELF), health concerns
<a style='text-decoration: underline;' href="http://www.niehs.nih.gov/emfrapid/extrmurabs/marino.html" target="_blank">http://www.niehs.nih.gov/emfrapid/extrmurabs/marino.html</a>

I very strongly suggest you go to this site, and read the links!
<a style='text-decoration: underline;' href="http://www.business.com/directory/human_resources/workplace_health_and_safety/environmental_issues/electric_and_magnetic_fields_emf/" target="_blank">http://www.business.com/directory/human_resources/workplace_health_and...fety/en</a>

Search criteria (sample)
<a style='text-decoration: underline;' href="http://www.google.com/search?q=long+term+effect+magnetic+fields+health&btnG=Google+Search" target="_blank">http://www.google.com/search?q=long+term+effect+magnetic+fields+health...nG=Goog</a>

ISO definitions
<a style='text-decoration: underline;' href="http://www.narda-sts.de/en/hilfe/schlagwortregister.htm" target="_blank">http://www.narda-sts.de/en/hilfe/schlagwortregister.htm</a>



--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage <a style='text-decoration: underline;' href="http://www.zoom-one.com" target="_blank">http://www.zoom-one.com</a>
Electronics <a style='text-decoration: underline;' href="http://www.zoom-one.com/electron.htm" target="_blank">http://www.zoom-one.com/electron.htm</a>
=========================================


"Sodah" <sodah6.DeleteThis@home.com> wrote in message
news:goX0c.646438$JQ1.309669@pd7tw1no...
Just to add an interesting footnote... Late evening/night (e.g. the present
moment) the 'flicker' diminishes _dramatically_. My guess is that this is
due to it being "off peak" hours for electricity demand (i.e. less energy
going through --and therefore, being emitted by-- the powerlines).


"DaveW" <none.DeleteThis@zero.org> wrote in message
news:hmQ0c.160011$uV3.707652@attbi_s51...
 > An LCD is about the only workable solution.
 >
 > --
 > DaveW
 >

Thought so. But I love my CRT monitor! So... before I decide to
throw-in-the-towel and "downgrade" to an LCD (just my personal
preference/opinion), I'm going to put just a little more time into looking
for some way to "magnetically shield" my monitor (i.e. the space it is in).
To anyone out there technically versed in such stuff (i.e. "magnetic
shielding"), I'd eagerly welcome any useful information/insight/etc. you
might be able to share towards this.

Thanks,

Sodah


 >
 >
 > "Sodah" <sodah6.DeleteThis@home.com> wrote in message
 > news:X4N0c.661124$X%5.80923@pd7tw2no...
  > > Hi!
  > > I just moved into my sisters place, which is adjacent to some
high-tension
  > > power-lines. Set up my computer yesterday, and immediately observed a
 > fine
  > > but pervasive 'flicker' on my (CRT) monitor (similar to what my sister
has
  > > been experiencing with her own two [CRT] computer monitors for years).
 > This
  > > is quite annoying, not to mention rapidly productive of eyestrain and
  > > fatigue. Based on my own monitor's past performance, coupled with my
  > > sister's consistent experience with her own monitors, it seems obvious
to
 > me
  > > that this 'flicker' is due entirely to electromagnetic-interference from
 > the
  > > power lines. What I would like to know, if anybody out there can tell
me,
  > > is: (1) Might there be any conceivable action I could take to better
 > shield
  > > my monitor from such electromagnetic interference (e.g. a commercial
 > add-on
  > > product, or home-made metallic shroud, etc...)? ; (2) Please correct me
 > if
  > > I am not right in my guess that (failing the above) replacing my CRT
 > monitor
  > > with an LCD monitor should avoid the problem (i.e. since the latter does
 > not
  > > utilize an electromagnetically-hypersensitive electron beam).
  > >
  > > Thanks in advance for any helpful advice, experience, links to info,
 > etc...
  > >
  > > Sodah
  > >
  > >
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

dummy DeleteThis @home.com wrote:
 >88 Hz works great, I've used it. Still some distortion, but not too
 >bad, right in a load center.
 >
 >At 60 Hz you get the slow flag wave. DUH

At 88 Hz you get a 28 Hz wave, which is faster than the human
eye can follow. However, that means your eye doesn't see each
change, and instead you see a wide, fuzzy vertical line rather
than a wavy vertical line.

The loss of definition may bother you as much or perhaps even
more than the wavy lines did!

 >"Bob Myers" <nospamplease DeleteThis @address.invalid> wrote:
  >>"Jerry G." <jerryg50 DeleteThis @hotmail.com> wrote:

   >>> Did you try to increase the scan rate to about 80 Hz or something like
  >>this?
  >>
  >>Actually, assuming that the problem IS magnetic interference, this
  >>is exactly the wrong advice. Minimizing the visible effects of such
  >>interference requires setting the refresh rate as close as possible
  >>to the local power frequency or an integer multiple of that.

That is essentially true, but doesn't help. The requirement is not
"as close as possible", but rather "closer than is possible"! You
have to *lock* the vertical rate to the power line frequency. That
is because both the power line and the monitor will change enough
over a day's time to cause a very slow wave unless the monitor tracks
the power. (The power lines have very good long term stability,
but that is an average, not an instantaneous accuracy.)

--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd DeleteThis @barrow.com<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

"Jerry G." <jerryg50.TakeThisOut@hotmail.com> wrote in message
news:c226o8$6i9$1@news.eusc.inter.net...
 > Did you try to increase the scan rate to about 80 Hz or something like
this?

Actually, assuming that the problem IS magnetic interference, this
is exactly the wrong advice. Minimizing the visible effects of such
interference requires setting the refresh rate as close as possible
to the local power frequency or an integer multiple of that.


 > Your monitor CRT is shielded by a u-metal ( mew-metal ) shied according
to
 > the international safety standards. This is to meet specific
requirements.
 > Any type of magnetic field that can pass through in any direction would be
 > considered excessively strong, or the shield in your monitor is not
adequate
 > according to established standards.

Nope. International standards do not cover magnetic
SUSCEPTIBILITY on the part of CRT monitors, only their
magnetic emissions. Those are generally NOT addressed through
internal shielding, and it is actually somewhat rare for a mainstream
CRT monitor these days to contain much, if any, "mu-metal" or
other magnetic shielding material. (There MAY be a bit within the
CRT itself, but even that is becoming less common.)

 > If you want to add shielding, the required type of metal is very
expensive,
 > and the design of the shield set-up would be complex. To shield out the
 > lower frequencies, such as the 50 and 60 Hz from AC power sources is more
 > complicated than to shield out high frequencies such as X-Ray and
microwave.

Mostly because in the former case, we ARE talking about a straight
magnetic field and not EM. Very different beasts.


 > My suggestion is that if you are living in a condition where the field is
so
 > strong to cause a monitor to flicker, you should strongly consider moving!
 > These fields are known to be dangerous over time. The power companies are
in
 > denial about this, because there are not many long term studies, and many
 > that have been done were not openly published.

It doesn't take much in the way of magnetic field strength to cause
visible problems on the monitor - in fact, the fields involved are generally
on roughly the same order of magnitude as the Earth's own field (and
you're not overly worried about THAT, I hope..) The problem is
that the power-line fields are AC, which causes the image on the screen to
move rapidly back and forth, and thus be visually objectionable. (The
Earth's own field also moves the image, but since it's a static displacement
you don't notice this as a problem.) In any event, the possible health
concerns over low-frequency magnetic fields have, IMHO, been
grossly overstated.


Bob M.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

Sodah wrote:

 > Hi!
 > I just moved into my sisters place, which is adjacent to some high-tension
 > power-lines.

Move. You can find plenty of information on Google about what high-tension
power-lines do to your health. If it interrupts a computer monitor in that way,
imagine what it's doing to your body.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

Unfortunately, mostly hysteria and paranoia, not science.

"before" <and DeleteThis @af.ter> wrote in message news:404467CC.CF0B0934@af.ter...
 >
 > Move. You can find plenty of information on Google about what high-tension
 > power-lines do to your health. If it interrupts a computer monitor in that
way,
 > imagine what it's doing to your body.
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

88 Hz works great, I've used it. Still some distortion, but not too
bad, right in a load center.

At 60 Hz you get the slow flag wave. DUH

On Tue, 02 Mar 2004 20:07:59 GMT, "Bob Myers"
<nospamplease DeleteThis @address.invalid> wrote:

 >
 >"Jerry G." <jerryg50 DeleteThis @hotmail.com> wrote in message
 >news:c226o8$6i9$1@news.eusc.inter.net...
  >> Did you try to increase the scan rate to about 80 Hz or something like
 >this?
 >
 >Actually, assuming that the problem IS magnetic interference, this
 >is exactly the wrong advice. Minimizing the visible effects of such
 >interference requires setting the refresh rate as close as possible
 >to the local power frequency or an integer multiple of that.
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

 > Also, assuming you are in a 60hz power location, change the scan rate of
the
 > monitor (if possible). This often helps.


Very true!! In fact I'm keeping my refresh rate at 60 hz (during "peak
hours", that is) as it does make quite a difference ... The image stops
shaking around (which, btw, further confirms the, "it's the powerlines",
explanation...). (Other available refresh rates don't do the trick.)
Unfortunately, 60 mhz itself inherently appears as 'strobe-like' (rather
than appearing to my eye as 'continuous and uninterrupted'), thus similarly
productive of eyestrain/fatigue/etc ... thus not a long term solution.


Thanx,
Sodah



"Charles Perry" <pipesandtobacco.RemoveThis@hotmail.com> wrote in message
news:c21itc$1fksb1$1@ID-103962.news.uni-berlin.de...
 >
 > "Sodah" <sodah6.RemoveThis@home.com> wrote in message
 > news:goX0c.646438$JQ1.309669@pd7tw1no...
  > > Just to add an interesting footnote... Late evening/night (e.g. the
 > present
  > > moment) the 'flicker' diminishes _dramatically_. My guess is that this
is
  > > due to it being "off peak" hours for electricity demand (i.e. less
energy
  > > going through --and therefore, being emitted by-- the powerlines).
 > Do a search on Google for mu metal . It works. It is VERY expensive
 > (around $300 for a monitor). You can probably do some good by changing
the
 > location of the monitor. You would be surprised at what a few feet can
do.
 > The strength of the field drops by the distance squared, so a small change
 > in the distance from the source can make a huge difference in the strength
 > of the field.
 >
 > Also, assuming you are in a 60hz power location, change the scan rate of
the
 > monitor (if possible). This often helps.
 >
 > Charles Perry P.E.
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

"Sodah" <sodah6 RemoveThis @home.com> wrote in message
news:2Ld1c.671740$X%5.68074@pd7tw2no...
  > > Also, assuming you are in a 60hz power location, change the scan rate of
 > the
  > > monitor (if possible). This often helps.
 >
 >
 > Very true!! In fact I'm keeping my refresh rate at 60 hz (during "peak
 > hours", that is) as it does make quite a difference ... The image stops
 > shaking around (which, btw, further confirms the, "it's the powerlines",
 > explanation...). (Other available refresh rates don't do the trick.)
 > Unfortunately, 60 mhz itself inherently appears as 'strobe-like' (rather
 > than appearing to my eye as 'continuous and uninterrupted'), thus
similarly
 > productive of eyestrain/fatigue/etc ... thus not a long term solution.
 >
 >
 > Thanx,
 > Sodah
 >
By the way, don't assume that those big power lines you see outside are the
cause. They often aren't. This type of interference is caused by magnetic
fields, which are caused by current. The strength of the field decreases by
the square of the distance. Those big lines often have no more current than
the low voltage ones attached to your home and they are much farther away.
It is very likely that the conductors causing the problem are low voltage
(600v or less). It could be the service conductor to the house (or
apartement building). It could also be a transformer. It could be wiring
in the wall.

Charles Perry P.E.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea.. 

"before" <and DeleteThis @af.ter> wrote in message news:404467CC.CF0B0934@af.ter...
 >[...].
 > Move. You can find plenty of information on Google about what high-tension
 > power-lines do to your health. If it interrupts a computer monitor in that
way,
 > imagine what it's doing to your body.
 >

I'm sorry, but I just don't get it. First of all ... the leap in the logic
(e.g. ... "disruption" of what is essentially a passively mechanistic,
designed-for-marketetability, consumer *appliance*... ===>>> ...
"disruption" of auto-homeostatic, dynamically self-repairing,, *living
organism*...). But even if I were to somehow see the logic here, I would
still be at a loss to explain why (without resorting to un-verifiable
speculation, rumour, etc.) why, after decades of public and scientific
inquiry into this question, the preponderance of the evidence fails to
support cause-for-concern.


Just my 2 cents,

Sodah<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Advice needed: CRT monitor 'flicker' problem caused by nea..