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Energy-saving bulbs that come on gradually
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Mortimer
Feb 2, 2012, 6:49:54 AM2/2/12
to
Why is it that some energy-saving bulbs come on almost immediately the power
is turned on and others come on very dimly and take a couple of minutes to
reach normal brightness? I'm talking about brand new bulbs, so age of the
bulb isn't (presumably) an explanation.
Is there any way to distinguish between the two types when buying them so as
to be able to buy quick-start bulbs for rooms where the bulb is the only
form of lighting and you need to be able to see as soon as you tunr on the
light to go into the room at night.
As a test, I used a camera exposure meter to measure brightness over time,
and found that a 40W-equivalent bulb comes on about 5 stops (2^5 = 32 times)
dimmer than its eventual brightness and takes about 2 1/2 minutes to reach
that brightness.
is turned on and others come on very dimly and take a couple of minutes to
reach normal brightness? I'm talking about brand new bulbs, so age of the
bulb isn't (presumably) an explanation.
Is there any way to distinguish between the two types when buying them so as
to be able to buy quick-start bulbs for rooms where the bulb is the only
form of lighting and you need to be able to see as soon as you tunr on the
light to go into the room at night.
As a test, I used a camera exposure meter to measure brightness over time,
and found that a 40W-equivalent bulb comes on about 5 stops (2^5 = 32 times)
dimmer than its eventual brightness and takes about 2 1/2 minutes to reach
that brightness.
Dr J R Stockton
Feb 5, 2012, 6:22:59 PM2/5/12
to
In uk.tech.misc message <I9GdnY2UzK_W5bfS...@brightview.co.
uk>, Thu, 2 Feb 2012 11:49:54, Mortimer <m...@privacy.net> posted:
LED bulbs, which I've seen in UK advertising but not in ordinary shops,
should turn on quickly. If they last as long as they should, and the
current compact fluorescents only last as long as mine seem to, they'll
be more economical to buy.
CF start-up time is temperature-dependent, slow when cold.
--
(c) John Stockton, near London. *@merlyn.demon.co.uk/?.?.Stockton@physics.org
Web <http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, and links.
Correct <= 4-line sig. separator as above, a line precisely "-- " (RFC5536/7)
Do not Mail News to me. Before a reply, quote with ">" or "> " (RFC5536/7)
uk>, Thu, 2 Feb 2012 11:49:54, Mortimer <m...@privacy.net> posted:
should turn on quickly. If they last as long as they should, and the
current compact fluorescents only last as long as mine seem to, they'll
be more economical to buy.
CF start-up time is temperature-dependent, slow when cold.
--
(c) John Stockton, near London. *@merlyn.demon.co.uk/?.?.Stockton@physics.org
Web <http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, and links.
Correct <= 4-line sig. separator as above, a line precisely "-- " (RFC5536/7)
Do not Mail News to me. Before a reply, quote with ">" or "> " (RFC5536/7)
Ian Field
Feb 5, 2012, 7:32:32 PM2/5/12
to
"Dr J R Stockton" <repl...@merlyn.demon.co.uk> wrote in message
news:0LxSrKmT...@invalid.uk.co.demon.merlyn.invalid...
> In uk.tech.misc message <I9GdnY2UzK_W5bfS...@brightview.co.
> uk>, Thu, 2 Feb 2012 11:49:54, Mortimer <m...@privacy.net> posted:
>
>>Why is it that some energy-saving bulbs come on almost immediately the
>>power is turned on and others come on very dimly and take a couple of
>>minutes to reach normal brightness? I'm talking about brand new bulbs,
>>so age of the bulb isn't (presumably) an explanation.
>>
>>Is there any way to distinguish between the two types when buying them
>>so as to be able to buy quick-start bulbs for rooms where the bulb is
>>the only form of lighting and you need to be able to see as soon as you
>>tunr on the light to go into the room at night.
>>
>>As a test, I used a camera exposure meter to measure brightness over
>>time, and found that a 40W-equivalent bulb comes on about 5 stops (2^5
>>= 32 times) dimmer than its eventual brightness and takes about 2 1/2
>>minutes to reach that brightness.
>
>
> LED bulbs, which I've seen in UK advertising but not in ordinary shops,
> should turn on quickly. If they last as long as they should, and the
> current compact fluorescents only last as long as mine seem to, they'll
> be more economical to buy.
Apparently there's a newly announced emerging technology for the production
> uk>, Thu, 2 Feb 2012 11:49:54, Mortimer <m...@privacy.net> posted:
>
>>Why is it that some energy-saving bulbs come on almost immediately the
>>power is turned on and others come on very dimly and take a couple of
>>minutes to reach normal brightness? I'm talking about brand new bulbs,
>>so age of the bulb isn't (presumably) an explanation.
>>
>>Is there any way to distinguish between the two types when buying them
>>so as to be able to buy quick-start bulbs for rooms where the bulb is
>>the only form of lighting and you need to be able to see as soon as you
>>tunr on the light to go into the room at night.
>>
>>As a test, I used a camera exposure meter to measure brightness over
>>time, and found that a 40W-equivalent bulb comes on about 5 stops (2^5
>>= 32 times) dimmer than its eventual brightness and takes about 2 1/2
>>minutes to reach that brightness.
>
>
> LED bulbs, which I've seen in UK advertising but not in ordinary shops,
> should turn on quickly. If they last as long as they should, and the
> current compact fluorescents only last as long as mine seem to, they'll
> be more economical to buy.
of LED lighting that should make prices fall by a lot.
Might be worth holding off a while and see how LED prices develop.
Mortimer
Feb 6, 2012, 2:32:38 PM2/6/12
to
"Dr J R Stockton" <repl...@merlyn.demon.co.uk> wrote in message
news:0LxSrKmT...@invalid.uk.co.demon.merlyn.invalid...
news:0LxSrKmT...@invalid.uk.co.demon.merlyn.invalid...
> In uk.tech.misc message <I9GdnY2UzK_W5bfS...@brightview.co.
> uk>, Thu, 2 Feb 2012 11:49:54, Mortimer <m...@privacy.net> posted:
>
>>Why is it that some energy-saving bulbs come on almost immediately the
>>power is turned on and others come on very dimly and take a couple of
>>minutes to reach normal brightness? I'm talking about brand new bulbs,
>>so age of the bulb isn't (presumably) an explanation.
>>
>>Is there any way to distinguish between the two types when buying them
>>so as to be able to buy quick-start bulbs for rooms where the bulb is
>>the only form of lighting and you need to be able to see as soon as you
>>tunr on the light to go into the room at night.
>>
>>As a test, I used a camera exposure meter to measure brightness over
>>time, and found that a 40W-equivalent bulb comes on about 5 stops (2^5
>>= 32 times) dimmer than its eventual brightness and takes about 2 1/2
>>minutes to reach that brightness.
>
>
> LED bulbs, which I've seen in UK advertising but not in ordinary shops,
> should turn on quickly. If they last as long as they should, and the
> current compact fluorescents only last as long as mine seem to, they'll
> be more economical to buy.
>
> CF start-up time is temperature-dependent, slow when cold.
Sorry, I should have said. All the energy-saving bulbs are CF. I think the
> uk>, Thu, 2 Feb 2012 11:49:54, Mortimer <m...@privacy.net> posted:
>
>>Why is it that some energy-saving bulbs come on almost immediately the
>>power is turned on and others come on very dimly and take a couple of
>>minutes to reach normal brightness? I'm talking about brand new bulbs,
>>so age of the bulb isn't (presumably) an explanation.
>>
>>Is there any way to distinguish between the two types when buying them
>>so as to be able to buy quick-start bulbs for rooms where the bulb is
>>the only form of lighting and you need to be able to see as soon as you
>>tunr on the light to go into the room at night.
>>
>>As a test, I used a camera exposure meter to measure brightness over
>>time, and found that a 40W-equivalent bulb comes on about 5 stops (2^5
>>= 32 times) dimmer than its eventual brightness and takes about 2 1/2
>>minutes to reach that brightness.
>
>
> LED bulbs, which I've seen in UK advertising but not in ordinary shops,
> should turn on quickly. If they last as long as they should, and the
> current compact fluorescents only last as long as mine seem to, they'll
> be more economical to buy.
>
> CF start-up time is temperature-dependent, slow when cold.
faster ones tend to be those with the tube exposed in a spiral, and the slow
ones are those with an outer glass envelope which covers the tube. All the
bulbs are at room temperature (say 20 deg C) and at least one of the slow
ones is no more than a couple of months old and was slow to start right from
the moment it was first used.
It would have been interesting if I'd kept a note of the brands of bulb to
see if all those of a certain brand are slow. I *think* the fast ones tend
to be supermarket's own brand and the slow ones are well-known brands.
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