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OT: Dimmable CFL

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N_Cook

Jan 1, 1970
0
Someone asked me and I don't know. Do they dim quantised or continuous, eg
1/2, 1/4, 1/8 with an existing lamp dimmer control, do they flicker on lower
setting? what colour do they emit at (if possible) 10 percent of full
rating? At 10 percent is overall power consumption more than an incandescent
at 10 percent? . Comfortable pinkish /orange at that level for conventional
bulb 100W run at 10W or so.
 
W

William Sommerwerck

Jan 1, 1970
0
Someone asked me and I don't know. Do they dim quantised
or continuous, eg 1/2, 1/4, 1/8 with an existing lamp dimmer
control, do they flicker on lower settings? What colour do they
emit at (if possible) 10 percent of full rating? At 10 percent is
overall power consumption more than an incandescent at 10
percent? Comfortable pinkish /orange at that level for a
conventional bulb 100W run at 10W or so.

You sure ask a lot of questions for someone from Jersey.

Several years ago I bought a GE dimmable CFL, which I never installed.
(Still sitting there.)

What do you mean by a "conventional" dimmer" -- a rheostat? Once you get
below a certain voltage, the lamp will shut off, whether or not it "dims".

The common type of dimmer in the US uses PWM. The Scottish-invented X10 is
the best example of this design. The X10 has 255 levels, but the GE dimmable
CFL works with only the first top 10 or so. The light gets dimmer, then goes
out abruptly. You don't have the range available with incandescent lamps.

I don't remember the color changing at all. It's controlled by the laws of
quantum mechanics, not the line voltage, so it shouldn't change. I don't
remember it flickering, either.

As for power savings... You can't meaningfully compare tungsten lamps
running at x% with fluorescent lamps running at x%.Tungsten lamps get less
efficient (that is, the percentage of electricity they convert into
/visible/ light drops) as the voltage drops. If you "always" dim a
particular incandescent light, you should replace it with a smaller lamp you
don't need to dim. This will use less electricity.

(If this isn't clear... A 100W bulb running at 50W produces less light than
a 50W bulb.)

By the way, tungsten-halogen lamps should not be dimmed "just a bit". If the
filament runs at a temperature slightly below the point at which the halgoen
reaction starts, the bulb will burn out prematurely. (I've seen this.)
Halogen bulbs should be dimmed "substantially".
 
P

PeterD

Jan 1, 1970
0
You sure ask a lot of questions for someone from Jersey.

Several years ago I bought a GE dimmable CFL, which I never installed.
(Still sitting there.)

What do you mean by a "conventional" dimmer" -- a rheostat? Once you get
below a certain voltage, the lamp will shut off, whether or not it "dims".

Was researching this the other day. The makers of 'dimmable' CFLs
recommend only certain dimmers (PWM), and do not recommend other
systems based on older technology.
The common type of dimmer in the US uses PWM. The Scottish-invented X10 is
the best example of this design. The X10 has 255 levels, but the GE dimmable
CFL works with only the first top 10 or so. The light gets dimmer, then goes
out abruptly. You don't have the range available with incandescent lamps.

I don't remember the color changing at all. It's controlled by the laws of
quantum mechanics

Since color is based on the phospor's visiable light spectrum, I doubt
that will change much at all...
 
G

GregS

Jan 1, 1970
0
Was researching this the other day. The makers of 'dimmable' CFLs
recommend only certain dimmers (PWM), and do not recommend other
systems based on older technology.


Since color is based on the phospor's visiable light spectrum, I doubt
that will change much at all...

Many years ago, probably 8-9 years, I converted the 500 watt halogen pole light
to 100 watt equiv. CFL drawing 23 watts or so. I used the same dimmer. The CFL was $20 at
the store. It worked great. The color temperature was very
good in that it appeared more halogen than halogen.
Many CFL's take some time to gain brightness as it
heats. On a lower setting it will take longer. It will go
to minimum brightness after setting to a higher level
then reducing. I saw no change in color temperature
with brightness, but color temperature may will
vary on warm up.

greg
 
D

D Yuniskis

Jan 1, 1970
0
N_Cook said:
Someone asked me and I don't know. Do they dim quantised or continuous, eg
1/2, 1/4, 1/8 with an existing lamp dimmer control, do they flicker on lower
setting? what colour do they emit at (if possible) 10 percent of full
rating? At 10 percent is overall power consumption more than an incandescent
at 10 percent? . Comfortable pinkish /orange at that level for conventional
bulb 100W run at 10W or so.

The (dimmable) CFL's sold here (US) are not really comparable
to incandescents. Their "briteness range" is probably something
like 60% to 100% corresponding to 20% to 100% of the range of a
"traditional" dimmer. Within that operating range, their
output *appears* to be continuously variable (i.e., no noticeable
steps in intensity)

Color temperature is largely unchanged over that range.

Intensity varies with time as the lamps take a while to
get up to operating temperature (?).

At the dimmer's lowest setting, the lamps don't appear to start
at all (at least not in any realistic time frame).

Our (personal) experience has found them to be very disappointing.
We've switched back to incandescents in all of the dimmer
applications in the house as it is just not possible to get
a very *low* level of light out of the CFL's.

HTH
 
N

N_Cook

Jan 1, 1970
0
D Yuniskis said:
The (dimmable) CFL's sold here (US) are not really comparable
to incandescents. Their "briteness range" is probably something
like 60% to 100% corresponding to 20% to 100% of the range of a
"traditional" dimmer. Within that operating range, their
output *appears* to be continuously variable (i.e., no noticeable
steps in intensity)

Color temperature is largely unchanged over that range.

Intensity varies with time as the lamps take a while to
get up to operating temperature (?).

At the dimmer's lowest setting, the lamps don't appear to start
at all (at least not in any realistic time frame).

Our (personal) experience has found them to be very disappointing.
We've switched back to incandescents in all of the dimmer
applications in the house as it is just not possible to get
a very *low* level of light out of the CFL's.

HTH


pwehaps for a fully dimmable situation you have to buy dimmer and bulb as
one package, 50 percent dimming is not what this person is after. Looks as
though they will have to stay with incandescents for that reason and they
like the orange/yellow/pink colouration at low levels
 
D

D Yuniskis

Jan 1, 1970
0
N_Cook said:
pwehaps for a fully dimmable situation you have to buy dimmer and bulb as

Dunno. We certainly aren't going to go through the house
replacing all of our "dimmers" (each with a "three way"
switch built in) just to accommodate CFL's. Presumably,
someone will "fix" this problem in the future...
one package, 50 percent dimming is not what this person is after. Looks as
though they will have to stay with incandescents for that reason and they
like the orange/yellow/pink colouration at low levels

Yup, that is the approach we have taken. Our lights are
placed such that on the lowest dimmer setting, there is
*just* enough light to see the general contents of the
room when it is pitch black outdoors. I.e., perfect
for waking up in the middle of the night and *not*
wanting to shock your eyes with an overly bright light
(the CFLs at their lowest visible setting are *way*
too bright for this purpose). This is ideal for house
guests who might be unfamiliar with the layout of the house
and who could benefit from our leaving the lights
"on, dim" at bedtime.
 
D

D Yuniskis

Jan 1, 1970
0
Dave said:
Don't think you've quite got your head round the idea of CFLs - to save
energy. ;-)

I can "save energy" by turning all the lights *off* (!)
but that wouldn't be a very pleasant way to live. :>
CFLs that only dim to half way is just as unpleasant
(in our application).

We'll wait for the problem to be "fixed" properly as
our lighting needs are pretty inconsequential (since
25% of the wall space in the rooms with these lights
is *glass*).
 
D

D Yuniskis

Jan 1, 1970
0
Dave said:
Dimming tungsten is horribly inefficient. Better to have smaller lights on
a second circuit.

And how do you justify the costs of having a licensed electrician
come in and add *those* second *circuits*? Followed by the drywall man
to clean up the (cosmetic) mess he leaves? Followed by the painter?
Easier to spend that money inefficently heating tungsten for the
next five (?) years -- until a genuine dimmable CFL comes along! :>
No night time where you live? ;-)

Activities at night either want subdued lighting (e.g.,
relaxing, listening to music, watching TV, etc.) *or*
take place in locations where lights are never dimmed
and, thus, use regular CFLs. For example, working at
the computer, cooking dinner (kinda hard to do this
in "dim light" :> ), reading, etc.

We had considered putting smaller (wattage) lamps in
those locations but then you are always stuck with
too little light.

It won't be long before the market's complaints about
dimmable CFLs cause manufacturers to come up with a viable
"screw in" replacement for incandescents with *conventional*
dimmers.
 
W

William Sommerwerck

Jan 1, 1970
0
Easier to spend that money inefficently heating tungsten
for the next five (?) years -- until a genuine dimmable CFL
comes along! :>

I don't think we'll ever have a "full range" dimmable CFL. At least, not one
that didn't badly flicker at lower levels.
 
D

D Yuniskis

Jan 1, 1970
0
William said:
I don't think we'll ever have a "full range" dimmable CFL. At least, not one
that didn't badly flicker at lower levels.

Why not? With enough smarts, you could excite it at 2 or 3 times
the line frequency -- but very low duty cycles...? I think it
is just a question of waiting for the electronics/magnetics to
get small enough on a practical scale.

E.g., years ago, the idea of a 500W, multiple output power supply
fitting in a ~30 cu in volume would have been unheard of... yet
now you can buy them for the price of an expensive lunch! :-/
 
G

GregS

Jan 1, 1970
0
I can "save energy" by turning all the lights *off* (!)
but that wouldn't be a very pleasant way to live. :>
CFLs that only dim to half way is just as unpleasant
(in our application).

We'll wait for the problem to be "fixed" properly as
our lighting needs are pretty inconsequential (since
25% of the wall space in the rooms with these lights
is *glass*).

I would say at least 1/10 the brightness or more when I have
done CFL dimming. For dim lighting the choice is obvious. Install
a separate led lighting system. It can stay on all the time
and have battery backup.

greg
 
D

David Nebenzahl

Jan 1, 1970
0
D

David Nebenzahl

Jan 1, 1970
0
They should have said droop because of temperature rise.
You need proper design.

Well, yes, if by "proper design" you mean "a type of LED that ain't been
invented yet".
 
G

GregS

Jan 1, 1970
0
They should have said droop because of temperature rise.
You need proper design.

Its not mysterious.
The small leds as shown in the article are easy to overdrive
and get very fast droop, and then permanent droop.
They even change color as they start to burn up.

The specs don't usualy say lm/watt
they give lumens at some wattage, usually 1.
If you decrease current, you get more lm/watt of course.
 
W

William Sommerwerck

Jan 1, 1970
0
They should have said droop because of temperature rise.
Its not mysterious.
The small leds as shown in the article are easy to overdrive
and get very fast droop, and then permanent droop.
They even change color as they start to burn up.
The specs don't usually say lm/watt
they give lumens at some wattage, usually 1.
If you decrease current, you get more lm/watt of course.

The article was specific about the conditions under which "droop" occurred,
and the fact that the cause is not understood.

This is interesting, because LEDs (red ones, at least) are generally more
efficient when pulsed at high currents.
 
W

William Sommerwerck

Jan 1, 1970
0
Sadly, I want decent quality light in my home. And no LED I've found yet
gives this. They can't seem to give a true daylight which would be fine
for some purposes -- or a reasonable imitation of tungsten for that "warm"
lighting when required.

No, not yet. Give 'em time.

Good quality fluorescent can, though -- but the choice of CFLs is too
limited at the moment to compete well with that.

I don't know. The $2 CFLs I get at Home Despot are terrific. The basic
balance is on the warm side, with no hint of blue or green. Though spec'd at
10K hours, they last about 2K. Which makes the purchase price no different
than incandescent lamps.

One way to get "warm" light is to use an appropriate shade. Three of mine
are mounted in Ikea glass "bullet" hanging fixtures, the fourth in Ikea's
cheap floor lamp. These shades add warmth. I also have two, without shades,
in the bath, on the "light bar" over the sink. Their unfiltered light is, to
my eyes, close to neutral, and definitely more pleasing the color of "warm"
conventional fluorescents in my kitchen.

Did I mention that they come on at more-than-useful brightness instantly,
and come to full brightness in about 30 seconds?

I don't know what everyone is complaining about. You can get really good,
cheap CFLs right now.

What more do you want?
 
W

William Sommerwerck

Jan 1, 1970
0
I don't know. The $2 CFLs I get at Home Despot are terrific.
It's not so much the perceived colour, but more what its light
does to other colours like paint etc. Due to the spectrum being
non-continuous or spikey. Of course tungsten alters colours,
too, compared to daylight but in a more subtle way.

I hope I don't sound unduly sarcastic when I ask... You're /that/ bothered
by metamerism?

I guess I'll have to photograph my Gretag-Macbeth chart under both the
cheapos (with and without shades) and the Lowell ego light (which is
supposed to give 90% "accurate" rendering), and see what happens. The latter
gives (to my eyes) essentially perfect rendition. (Yes, my monitor is
calibrated.)
 
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