Fluorescents and migraines??

On 13 Jan 2008 04:47:29 GMT, snipped-for-privacy@ipal.net wrote:


You can only use this method if you don't need a DC link voltage near the peak power line voltage.
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| alt.engineering.electrical, snipped-for-privacy@ipal.net says...
wrote:
|> |
|> |> |> |>| Does the spectrum cause migranies and "skin eruptions"? I thought |> |>| migraines were flicker rate which should be a non-issue with CFLs. |> |> |> |>I see CFLs that flicker. Probably very cheap ones. But they exist. |> |> |> |>BTW, I bought an LED flashlight the other day that has a white spectrum |> |>that does not bother me like other LEDs and all fluorescents and metal |> |>halides do. And it's a rather bright and well built one. LEDs are now |> |>looking more like they could be my future efficient lighting method. |> | |> | Line-powered LEDs can also flicker if the DC link is not |> | properly filtered. |> |> No doubt. Maybe one day the lighting industry will figure out how to |> properly smooth out the DC? Hint: it can be done without those big |> capacitors that power supplies of days gone by had. One idea that |> comes to mind is to chop the current with a pulse width varied to |> compensate for the lower frequency component(s) of the ripple. | | The same energy has to be stored.
Stored? What do you mean stored? That's not the only way to do it.
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alt.engineering.electrical, snipped-for-privacy@ipal.net says...

I see what VR is talking about but that's going to play hell with the PF. The EU isn't going to like that much and I'd imagine the US won't wait forever, particularly if every light bulb on the planet plays these games. There are two zeros per cycle to "smooth over".
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| alt.engineering.electrical, snipped-for-privacy@ipal.net says...
wrote:
|> |> |
|> |> |> |> |> |>| Does the spectrum cause migranies and "skin eruptions"? I thought |> |> |>| migraines were flicker rate which should be a non-issue with CFLs. |> |> |> |> |> |>I see CFLs that flicker. Probably very cheap ones. But they exist. |> |> |> |> |> |>BTW, I bought an LED flashlight the other day that has a white spectrum |> |> |>that does not bother me like other LEDs and all fluorescents and metal |> |> |>halides do. And it's a rather bright and well built one. LEDs are now |> |> |>looking more like they could be my future efficient lighting method. |> |> | |> |> | Line-powered LEDs can also flicker if the DC link is not |> |> | properly filtered. |> |> |> |> No doubt. Maybe one day the lighting industry will figure out how to |> |> properly smooth out the DC? Hint: it can be done without those big |> |> capacitors that power supplies of days gone by had. One idea that |> |> comes to mind is to chop the current with a pulse width varied to |> |> compensate for the lower frequency component(s) of the ripple. |> | |> | The same energy has to be stored. |> |> Stored? What do you mean stored? That's not the only way to do it. | | I see what VR is talking about but that's going to play hell with | the PF. The EU isn't going to like that much and I'd imagine the | US won't wait forever, particularly if every light bulb on the | planet plays these games. There are two zeros per cycle to "smooth | over".
The flicker will be worse in Europe.
So basically, it comes down to producing smooth DC while keeping PF near 1. And it would seem LEDs have the same issue.
Incandescent avoids the issue by having a long term temperature filament. That is, the filament remains hot even during zero crossing. So what about a phosphor that can continue to glow at the same color? FYI, I do see the existing phosphors glowing at zero crossing, but the color is different.
Or maybe we just need DC distributed in the home. But don't get any idea that Edison was right ... he was selling pulsing DC.
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<Big Snip>

That's interesting. What do you mean by "pulsing DC" --- unregulated? The Smithsonian historical material indicates that the steam-powered generators were speed regulated and the load was just incandescent lamps initially, of course.
Terry McGowan
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| | | <Big Snip> | |> |> Or maybe we just need DC distributed in the home. But don't get any idea |> that Edison was right ... he was selling pulsing DC. |> |> -- |> ----------------------------------------------------------------------------- |> | Phil Howard KA9WGN | http://linuxhomepage.com/ |> http://ham.org/ | |> | (first name) at ipal.net | http://phil.ipal.org/ |> http://ka9wgn.ham.org/ | |> ----------------------------------------------------------------------------- | | That's interesting. What do you mean by "pulsing DC" --- unregulated? The | Smithsonian historical material indicates that the steam-powered generators | were speed regulated and the load was just incandescent lamps initially, of | course.
Edison's generators output DC by reversing the electrical connections every half cycle. The end result is basically the same as a full wave rectifier bridge. You get 2 pulses per cycle. I don't know what speed his generators actually ran at.
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Edison's generators were rather clever: they had a bus bar equilizer so each shared the load equally (varied the field coil?). If the generators were intentionally out of phase, that would smooth out the combined output.
and a related story: many NYC buildings still depended on DC power for elevators and ancient parts:
http://cityroom.blogs.nytimes.com/2007/11/14/off-goes-the-power-current-started-by-thomas-edison /
November 14, 2007 Off Goes the Power Current Started by Thomas Edison
By Jennifer 8. Lee Con Edison's original power plant on Pearl Street.
Today, Con Edison will end 125 years of direct current electricity service that began when Thomas Edison opened his Pearl Street power station on Sept. 4, 1882. Con Ed will now only provide alternating current, in a final, vestigial triumph by Nikola Tesla and George Westinghouse, Mr. Edison's rivals who were the main proponents of alternating current in the AC/DC debates of the turn of the 20th century.
The last snip of Con Ed's direct current system will take place at 10 East 40th Street, near the Mid-Manhattan Library. That building, like the thousands of other direct current users that have been transitioned over the last several years, now has a converter installed on the premises that can take alternating electricity from the Con Ed power grid and adapt it on premises. Until now, Con Edison had been converting alternating to direct current for the customers who needed it ... old buildings on the Upper East Side and Upper West Side that used direct current for their elevators for example. ...
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http://cityroom.blogs.nytimes.com/2007/11/14/off-goes-the-power-current-started-by-thomas-edison /
Just like the newer cars, there could well be both AC and DC circuits in houses and other buildings. In fact, that's already happening. Why the old debate about which is "best"? Use what works most efficiently and economically for the application.
Terry McGowan
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|>|> Or maybe we just need DC distributed in the home. But don't get any idea |>|> that Edison was right ... he was selling pulsing DC. | |>| That's interesting. What do you mean by "pulsing DC" --- unregulated? The |>| Smithsonian historical material indicates that the steam-powered generators |>| were speed regulated and the load was just incandescent lamps initially, of |>| course. | |>Edison's generators output DC by reversing the electrical connections every |>half cycle. The end result is basically the same as a full wave rectifier |>bridge. You get 2 pulses per cycle. I don't know what speed his generators |>actually ran at. | | Edison's generators were rather clever: they had a bus bar equilizer | so each shared the load equally (varied the field coil?). | If the generators were intentionally out of phase, | that would smooth out the combined output.
2 or 3 alternators on the same rotor shaft, aligned at different angles, could do that phase shift, I suppose.
Interesting concept ... 3 phase DC. I've seen circuits for AC to DC power supplies that were designed to use 3 phase AC power to get smoother DC by means of 3 full-wave bridges. I never worked out what kind of current each of the 3 AC phase lines would have. The one I first saw was wired delta.
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snipped-for-privacy@ipal.net wrote:

Why stop at three? There are already DC/DC converters that use six "phases". The trade off is between circuit complexity and smoothing capacitors required. With IC components the former is trivial.
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| snipped-for-privacy@ipal.net wrote: | |> Interesting concept ... 3 phase DC. I've seen circuits for AC to DC power |> supplies that were designed to use 3 phase AC power to get smoother DC by |> means of 3 full-wave bridges. I never worked out what kind of current each |> of the 3 AC phase lines would have. The one I first saw was wired delta. | | Why stop at three? There are already DC/DC converters that use six | "phases". The trade off is between circuit complexity and smoothing | capacitors required. With IC components the former is trivial.
If by "six" you mean also to include the 180 degree opposing phases, that would be what I include in "three" phases (six pulse). The result would be a 300 or 360 Hz ripple for the capacitors to handle. If you get three phase power in, that is perhaps the simple setup. But you could also get a true six phases (twelve pulse) by having separate secondary windings on the 3 core transformer where 1 set are used for three of the phases, and another set or two are used in pairs from separate cores to get cross phase angles. You could also do this with a lot of separate transformers, but doing it with just 3 cores seems the most economical. Then the ripple would be 600 or 720 Hz and the capacitors could be even smaller.
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snipped-for-privacy@ipal.net wrote:

12 pulse converters are used routinely in variable frequency drives.
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| snipped-for-privacy@ipal.net wrote:
|>> |>>> Interesting concept ... 3 phase DC. I've seen circuits for AC to |>>> DC power supplies that were designed to use 3 phase AC power to get |>>> smoother DC by means of 3 full-wave bridges. I never worked out |>>> what kind of current each of the 3 AC phase lines would have. The |>>> one I first saw was wired delta. |>> |>> Why stop at three? There are already DC/DC converters that use six |>> "phases". The trade off is between circuit complexity and smoothing |>> capacitors required. With IC components the former is trivial. |> |> If by "six" you mean also to include the 180 degree opposing phases, |> that would be what I include in "three" phases (six pulse). The |> result would be a 300 or 360 Hz ripple for the capacitors to handle. |> If you get three phase power in, that is perhaps the simple setup. |> But you could also get a true six phases (twelve pulse) by having |> separate secondary windings on the 3 core transformer where 1 set are |> used for three of the phases, and another set or two are used in |> pairs from separate cores to get cross phase angles. You could also |> do this with a lot of separate transformers, but doing it with just 3 |> cores seems the most economical. Then the ripple would be 600 or 720 |> Hz and the capacitors could be even smaller. |> | | 12 pulse converters are used routinely in variable frequency drives.
Right. But is it worth doing 12 pulse AC to DC conversion? Is the cost of the extra transformer windings less than the savings in capacitors for typical ripple reduction requirements?
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snipped-for-privacy@ipal.net wrote: [snip]

I don't think that can be easily arranged. The mechanics of fluorescence are different from the mechanics of phosphorescence.

And glow at the crossing is from phosphorescence and additionally it depends on the kind of phosphor used.
I am still trying to figure out what in the world you guys are talking about.
I either must be blind or something else is at play here.
The flicker of, say, a PHILIPS TL-D/55/56 35W, is /colossal/ compared to the flicker of my 2700K CFLs. As far as I am concenred, I don't perceive /any/ flicker on my CFLs.
The only time I saw my CFLs flickering was when there was a voltage drop in my appartment, because all four kitchen ones flickered simultaneously.
Are we talking about non-perceptible flicker?
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| snipped-for-privacy@ipal.net wrote: | [snip] |> The flicker will be worse in Europe. |> |> So basically, it comes down to producing smooth DC while keeping PF |> near 1. And it would seem LEDs have the same issue. |> |> Incandescent avoids the issue by having a long term temperature |> filament. That is, the filament remains hot even during zero |> crossing. So what about a phosphor that can continue to glow at the |> same color? | | I don't think that can be easily arranged. The mechanics of fluorescence are | different from the mechanics of phosphorescence.
They can be mixed. So why not? I just don't know what colors would be an option or available.
|> FYI, I do see the existing phosphors glowing at zero |> crossing, but the color is different. | | And glow at the crossing is from phosphorescence and additionally it depends on | the kind of phosphor used.
I'm just tossing the idea out. I'm not an expert on specific kinds of phosphors.
| I am still trying to figure out what in the world you guys are talking about. | | I either must be blind or something else is at play here. | | The flicker of, say, a PHILIPS TL-D/55/56 35W, is /colossal/ compared to the | flicker of my 2700K CFLs. As far as I am concenred, I don't perceive /any/ | flicker on my CFLs.
Maybe you have one of the good ones I've read about that don't flicker.
| The only time I saw my CFLs flickering was when there was a voltage drop in my | appartment, because all four kitchen ones flickered simultaneously. | | Are we talking about non-perceptible flicker?
The 100 Hz or 120 Hz (depending on country) blinking.
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snipped-for-privacy@ipal.net wrote: [snip]

Every single one I've owned, from the first PHILIPS SL-18W which used a magnetic ballast back in 1980, to cheapo chinese ones to the modern OSRAM DULUX 27W and daylight NARVA 27W, don't flicker.
I have no idea what you guys are talking about.
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I.N. Galidakis wrote:

I've also asked my mother, two neighbors, my aunt and another visitor.
Nobody can detect any perceptible flicker on my 4 OSRAM DULUX 27W/2700K installed in my mother's kitchen.
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| snipped-for-privacy@ipal.net wrote: | [snip] | |>> I am still trying to figure out what in the world you guys are |>> talking about. |>> |>> I either must be blind or something else is at play here. |>> |>> The flicker of, say, a PHILIPS TL-D/55/56 35W, is /colossal/ |>> compared to the flicker of my 2700K CFLs. As far as I am concenred, |>> I don't perceive /any/ flicker on my CFLs. |> |> Maybe you have one of the good ones I've read about that don't |> flicker. | | Every single one I've owned, from the first PHILIPS SL-18W which used a magnetic | ballast back in 1980, to cheapo chinese ones to the modern OSRAM DULUX 27W and | daylight NARVA 27W, don't flicker.
Are we talking about different people's ability to see, or not see, flicker?
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alt.engineering.electrical, snipped-for-privacy@ipal.net says...

That's another of the problems with CFLs. You have no idea exactly what you're buying. If a poor choice is made buying an incandescent it just doesn't last as long. If a poor choice is made with a CFL you're stuck with expensive (and unreliable) crappy light. It's like chocolate...
<snip>
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<edit for space>

If I buy a CFL that I don't like and it costs more than $2, I take it back and get a refund. And I say why I don't like it.
The most recent time I did that was with N:Vision 3500K spirals of a higher wattage (I forget how many watts). Reason for return: They audibly buzzed. That was a little over a year ago.
Return bad ones, and the manufacturers get feedback.
- Don Klipstein ( snipped-for-privacy@misty.com)
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