|
[email protected] wrote:
| [snip]
|
|> Don't believe what you read in Wikipedia, unless they get lucky and
|> have something correct (it happens often, but not in this case).
|>
|> The purpose of the ballast is...
|
| [snip ballast explanation for brevity]
|
| Do I look to you like I need a tutorial on what is a ballast? If that's the
| impression I gave you, either my exposition powers are weak or your
| comprehension abilities are not up to par.
I've looked at lots of people, and I've never found any real easy means to
determine from their appearance, mannerisms, hygiene, or other aspects,
whether then need a tutorial on what a ballast is, or not. That, and I
didn't even look at you at all, since this is the Internet. So it's just
a crapshoot. But you were looking in Wikipedia for information. That is
enough to make me worry.
|>> and later down:
|>>
|>> "Electronic ballasts do not produce light flicker, since the phosphor
|>> persistence is longer than a half cycle of the higher operation
|>> frequency.
|>
|> They do not _produce_ it. They may let it pass through by not
|> storing any energy to "cover" the zero-crossover time period.
|>
|> Magnetic ballasts do not _produce_ flicker either.
|
| Wikipedia is not an engineering manual. For the lay person their explanation is
| correct. There is no point in arguing insignificant minutae with me (or with
| Wikipedia). /Of course/ ballasts do not "produce" flicker (literally), since
| they are not the main power supply which drives the lamp. But from a
| non-technical standpoint, it's the inductive resistance of the ballast which
| allows the AC cycle to propagate FROM the AC source to the lamp almost
| unchanged, making it seem as "flicker", for whatever reason, whether it be
| insufficient attenuation of the AC signal, bad power factor, "flattening" of the
| AC signal, lack of capacitors or whatever have you.
The resistance in the inductor has nothing to do with it. Maybe you meant to
say "impedance" instead of "resistance".
Using the correct terms can, in quite many cases, be very crucial. If you want
to be an engineer (even if you just want to play an arm-chair engineer on the
Internet), learn to use the correct terms. I had to.
If you want to simplify things, or even over-simplify things, that's one
thing. But when things just get wrong, that gives me cause for concern.
I've had to deal with (in my field, computer software) people who too often
take something that was a simplification as being something of detail and
ended up with an entirely wrong understanding. I not saying you have
misunderstood these technical things; I'm concerned more about what others
might read from Wikipedia or your quotations.
| What really matters here is what Wiki says later, which you conveniently did not
| address:
|
| "Electronic ballasts do not produce light flicker, since the phosphor
| persistence is longer than a half cycle of the higher operation frequency."
|
| As far as I am concerned, THAT's the crucial point which proves there's no
| flicker.
Still, that is incorrect.
That statement from Wikipedia suggests that it is the persistence of the
phosphor that makes the electronic ballast not produce flicker. That is
not just wrong, it's even silly.
Phosphor persistence can help reduce flicker. In very extreme cases it could
even eliminate it, in theory (but expect the light to continue to glow for a
very long time after you turn it off). This effect would be the same whether
the lamp current was being limited by an inductive ballast, capacitive ballast,
resistive ballast (no one would use such a beast, but one could be made), or an
electronic solid-state ballast.
Try this statement on for size:
"Magnetic ballasts do not produce light flicker, since the phosphor
persistence is longer than a half cycle of the higher operation frequency."
Is that any more or less "correct" in the context of Wikipedian engineering
than what you quoted from there?
| Of course, if you say that you see flicker, there's no way for me to convince
| you otherwise. If I claim that yesterday I saw a grand pink elephant nest with
| green eggs and ham sitting at the center of a primordial black hole, there's no
| way for you to prove me wrong either.
There are a lot of things I see in a lot of aspects of the world that a lot of
people try to convince me is not really there. THEY don't see it, so as far
as they are concerned, it really isn't there. I hope you are not slipping into
that category.
I wouldn't even try to prove you wrong on your sighting, even though I am
quite certain that black holes have no center.
|>> The non-visible 100?120 Hz flicker from fluorescent tubes powered by
|>> magnetic ballasts is associated with headaches and eyestrain."
|>
|> Some people _can_ see it. Some people need to roll their eyes to see
|> that it is there. Some people can just see it directly. It seems
|> most people cannot see it either way.
|
| I am not talking about whether one can see it by rolling one's eyes back and
| forth. I can see flickering even on incandescent sources if I roll my eyes back
| and forth. The question is whether a lay person can perceive consciously 100-120
| Hz flicker without doing a circus act with one's eyeballs. THAT's the question.
And I can see the flicker directly. I just can't see very accurately how MUCH
there is, or how much of it is compensated by the phosphors. When I do scan
my eyes across, I can see things that give me more information. If the light
is literally on and off that tells me one thing. If the light descends into a
different color, that tells me another (phosphor persistence is usually variant
in color in fluorescent lighting ... the totally color you get is the average
over time).
| It's a question of whether the perceptual system "eye-brain" has the capacity to
| perceive this flicker on standing mode ON A CONSCIOUS LEVEL and whether this
| flicker can cause headaches.
I can see the flicker from most fluorescent lights even when only viewing the
reflection of it from broad surfaces.
However, I have found that this does NOT cause headaches for me. I cannot say
if it does or does not cause it for others. I used to THINK that the flicker
was the cause, basically because it had been suggested for decades.
| I am ready to agree that although the flicker itself may not be /visible/ on a
| CONSCIOUS (PERCEPTUAL) LEVEL, the brain may be able to pick it up
| subconsciously. That's a contention I am ready to argue about, as a potential
| source of migranes. The rest is irrelevant.
I certainly cannot just count the 120 pulses per second. I can see that it is
flickering, but I cannot see individual pulses happening. I do not see it as
going on and off. I see the sense of flicker. I see it in some LEDs but not
in others. The ones that are battery powered don't have the flicker. Yet they
can cause the headaches.
|>> How come nobody had headaches back then?
|>>
|>> Or did they?
|>
|> I did! I just misunderstood exactly why. Back then I thought it was
|> _because_ of the flicker. Now I understand it is because of the
|> spectrum.
|
| Huh? How can you be sure without knowing the EXACT cause of what bothers you in
| the spectrum?
|
| Or if you DO know the exact cause, what is it that bothers you in the spectrum?
The spectrum is not continuous. It has a large gap or two large gaps in it.
My eyes do not focus all colors at an equal distance. Glasses exacerbate
that problem (more so at the edges of the glass). As a result, the edges
where light is different, such as the edge of black text on a white page,
is not in perfect focus. With a smooth continuous spectrum, it will appear
to be slightly fuzzy, but tolerable. With a broken spectrum, there will
appear to be 2 or more distinct edges. In the latter case, my eyes are
constantly jumping back and forth trying to focus in one color or the other.
That constant refocusing creates stress, and eventually a headache. This
is what appears to be going on for me. I do not know if others have the
this kind of issue or not. I do not know if they can get headaches from
other things that don't affect me. I've learned that people are sufficiently
different to never make such assumptions (although I've met many people that
have not learned that for themselves).