WTD: Problem with halogen lamps on dimmers
Jim Adney
all around the house I kept seeing various lights that would suddenly
dim for a second, or part of a second, then come back up. I assumed
that there was a bad connection somewhere, probably at the breaker
box, but later when I mentioned it to the host he said that he had
worked on the problem for years and had eliminated that possibility.
Here's what he told me: The house has lots of fixtures for PAR
(parabolic aluminized reflector) lamps which can be purchased in
either halogen or incandescent versions. The problem seems to be
related to his preference for halogen lamps. He has these all over
the house because of their greater efficiency and whiter light. He has
discovered that if he replaces the halogens with normal incandescent
PARs the problem goes away. In general, the halogens are of lower
wattage than the normal incandescents.
The problem occurs only with halogen lamps that are on dimmers, and
usually then it only happens at reduced intensity. If more than 1 bulb
is powered off the same dimmer then all the bulbs on that dimmer
flicker together. He showed me that with a mix of incandescent and
halogen bulbs on the same BREAKER circuit, only the halogens (which
were on a dimmer) flickered, so it seemed like the breaker box is not
the problem.
In the end it seems clear from his observations that the problem must
be with the dimmers, but he has added more over the years and they
have been of various brands. Still, they all seem to have this same
problem.
As a separate observation he pointed out that the dimmers were usually
unable to dim the halogens all the way off, while this was easy with
the normal bulbs. He also showed me that there was hysterisis in the
on/off point with the halogens that the normal bulbs didn't have.
Does anyone have an explanation for the flicker? Or a fix? Or even
seen this before?
Jim
-
-----------------------------------------------
Jim Adney jad...@vwtype3.org
Madison,Wisconsin USA
-----------------------------------------------
Lee
There is one important piece of information needed, does this happen if
the halogen bulbs are the *same* wattage as the GLS ones?
A lot of consumer grade dimmers have problems with low-wattage bulbs at
low light levels, it could be that he
is turning the halogen light down too low for the dimmer.
I have never had this problem using halogen lamps and *professional*
dimmers.
Lee
--
"It does not pay to leave a live dragon out of your calculations."
Tolkien
JURB6006
subtracts a set (by the control) amount of voltage from the line voltage.
Now if you have 120 volts and are subtracting 60, let's say a motor somewhere
starts up and makes the line voltage drop to 108 momentarily. That's only 10%
of the line voltage and the dimming won't be very noticeable, but when you are
subtracting 60, then it drops to 48. That's 20%, and alot more noticeable.
Sam Goldwasser
sensitive to voltage dips. You will probably find that the dimming is
well corellated with the power cycling of the central A/C, fridge, or some
other large appliance. It's annoying but that's about it.
This does mean that the wiring may be marginal or poorly distributed though
I too have seen this in houses where cost or poor design were probably not
an issue.
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Lee
Yes, but you did not specifically answer his question as to why the halogen bulbs are more
susceptible to the phenomenon than the GLS ones.
Or maybe the characteristics of the lamp show the effect more easily?
Of course what he really needs is a decent dimmer that has feedback control to cancel out
the voltage drops on the line -- if it really annoys him that much!!!
James Sweet
responds more quickly to the change in voltage.
Asimov
WTD: Problem with halogen lamps on dimmers (21 Nov 99 13:30:18)
I think there is an easy explanation. It occured to me over the summer
to replace the little 6 volt bulb in my bicycle headlight with a
similar wattage halogen type. When I went out later that evening I
noticed that once I got above a certain speed that the pedaling became
easier. This also corresponded with the lamp suddenly brightning.
What I understood from the experiment is that the halogen mechanism has
a threshold point above which it starts to activate. Below that
threshold only the filament is operating at a relatively lower
temperature. The pedal effort is greater because it draws more current.
So as I see it the dimmer in your buddy's setup is probably finding it
harder to get the lamps temperature high enough to activate the halogen
gas. There is quite a bit of hysterisis once the halogen activates
aiding the filament. The difference in temperature between where the
halogen becomes activated and where it stops is relatively large hence
the big hysterisis effect, i.e. flicker.
JA> I was at a party last night at a very nice home where I noticed that
JA> all around the house I kept seeing various lights that would suddenly
JA> dim for a second, or part of a second, then come back up. I assumed
JA> that there was a bad connection somewhere, probably at the breaker
JA> box, but later when I mentioned it to the host he said that he had
JA> worked on the problem for years and had eliminated that possibility.
JA> Here's what he told me: The house has lots of fixtures for PAR
JA> (parabolic aluminized reflector) lamps which can be purchased in
JA> either halogen or incandescent versions. The problem seems to be
JA> related to his preference for halogen lamps. He has these all over
JA> the house because of their greater efficiency and whiter light. He has
JA> discovered that if he replaces the halogens with normal incandescent
JA> PARs the problem goes away. In general, the halogens are of lower
JA> wattage than the normal incandescents.
JA> The problem occurs only with halogen lamps that are on dimmers, and
JA> usually then it only happens at reduced intensity. If more than 1 bulb
JA> is powered off the same dimmer then all the bulbs on that dimmer
JA> flicker together. He showed me that with a mix of incandescent and
JA> halogen bulbs on the same BREAKER circuit, only the halogens (which
JA> were on a dimmer) flickered, so it seemed like the breaker box is not
JA> the problem.
JA> In the end it seems clear from his observations that the problem must
JA> be with the dimmers, but he has added more over the years and they
JA> have been of various brands. Still, they all seem to have this same
JA> problem.
JA> As a separate observation he pointed out that the dimmers were usually
JA> unable to dim the halogens all the way off, while this was easy with
JA> the normal bulbs. He also showed me that there was hysterisis in the
JA> on/off point with the halogens that the normal bulbs didn't have.
JA> Does anyone have an explanation for the flicker? Or a fix? Or even
JA> seen this before?
JA> Jim
JA> -
JA> -----------------------------------------------
JA> Jim Adney jad...@vwtype3.org
JA> Madison,Wisconsin USA
JA> -----------------------------------------------
JA> -!-
JA> ! Origin: Juxtaposition BBS <-> Internet Gateway (17:5141/2)
... If plugging it in doesn't help, turn it on.
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Sam Goldwasser
life, not behavior with respect to brightness other than the usual - hotter
is brighter. Cheap dimmers set to near extinction are very sensitive to
voltage dips - probably the central A/C or something else kicks in and
causes the brightness fluctuations.
--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Asimov
Re: WTD: Problem with halogen lamps on dimmers (22 Nov 99 08:47:58)
SG> The temperature of the filament and tha halogen cycle have to do with
SG> lamp life, not behavior with respect to brightness other than the usual
SG> - hotter is brighter. Cheap dimmers set to near extinction are very
SG> sensitive to voltage dips - probably the central A/C or something else
SG> kicks in and causes the brightness fluctuations.
I think you are overlooking the phase change transition from metal to
vapour. If you're familiar with steam generation, water will absorb a
lot of energy before it reaches the boiling point and evaporates. My
guess was the same sort of phase change transition energy storage takes
place with the tungsten filament before releasing the energy as it
evaporates into the halogen gas.
Okay, where's a lighting expert when we need one? <g>
... 'Keep the smoke inside.' -- 1st Rule of Electronics.
Sam Goldwasser
normal tungsten lamp or a halogen is still miniscule in the short term.
It's not going to affect visible behavior.
--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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sparky
bulbs, the filament in the halogen has different chacteristics then a
normal incandesent bulb and requires different electronic circuitry to
properly maintain the required voltage and dim the bulb.
Jim Adney wrote:
>
> I was at a party last night at a very nice home where I noticed that
> all around the house I kept seeing various lights that would suddenly
> dim for a second, or part of a second, then come back up. I assumed
> that there was a bad connection somewhere, probably at the breaker
> box, but later when I mentioned it to the host he said that he had
> worked on the problem for years and had eliminated that possibility.
>
> Here's what he told me: The house has lots of fixtures for PAR
> (parabolic aluminized reflector) lamps which can be purchased in
> either halogen or incandescent versions. The problem seems to be
> related to his preference for halogen lamps. He has these all over
> the house because of their greater efficiency and whiter light. He has
> discovered that if he replaces the halogens with normal incandescent
> PARs the problem goes away. In general, the halogens are of lower
> wattage than the normal incandescents.
>
> The problem occurs only with halogen lamps that are on dimmers, and
> usually then it only happens at reduced intensity. If more than 1 bulb
> is powered off the same dimmer then all the bulbs on that dimmer
> flicker together. He showed me that with a mix of incandescent and
> halogen bulbs on the same BREAKER circuit, only the halogens (which
> were on a dimmer) flickered, so it seemed like the breaker box is not
> the problem.
>
> In the end it seems clear from his observations that the problem must
> be with the dimmers, but he has added more over the years and they
> have been of various brands. Still, they all seem to have this same
> problem.
>
> As a separate observation he pointed out that the dimmers were usually
> unable to dim the halogens all the way off, while this was easy with
> the normal bulbs. He also showed me that there was hysterisis in the
> on/off point with the halogens that the normal bulbs didn't have.
>
> Does anyone have an explanation for the flicker? Or a fix? Or even
Asimov
Re: WTD: Problem with halogen lamps on dimmers (22 Nov 99 21:29:14)
sp> you have to use a special halogen dimmer which is engineered for
sp> halogen bulbs, the filament in the halogen has different chacteristics
sp> then a normal incandesent bulb and requires different electronic
sp> circuitry to properly maintain the required voltage and dim the bulb.
Ahhh! Thank you...
... If plugging it in doesn't help, turn it on.
Jim Adney
>No mystery. When dimmed to near exttinction, the phase angle is extremely
>sensitive to voltage dips. You will probably find that the dimming is
>well corellated with the power cycling of the central A/C, fridge, or some
>other large appliance. It's annoying but that's about it.
While this sounds good, I don't think it is the answer in this case,
for 2 reasons: The flicker rate was higher than I would normally
expect (2 or 3 times a minute) and the flicker of lamps on different
dimmers did not seem to be related. Also, this would not explain why
normal incandescents did not also exibit the same phenomenum when
turned down.
While I was there the outside temp was just slightly chilly so that
with 100 people in the house I doubt if either the heat or the AC were
cycling much at all. I don't think they were using the microwave, but
they might have been using the oven. Of course the refrigerator was
running, and possibly a freezer.
>This does mean that the wiring may be marginal or poorly distributed though
>I too have seen this in houses where cost or poor design were probably not
>an issue.
Certainlly a possibility except for the fact that this should affect
halogens and normal lamps equally.
Additional info: the halogen lamps were smaller than the normal ones,
but not by much. I don't know all of what he was using, but I think he
said that in one case the difference was 125W vs. 150W. In many cases
the sizes were equal.
BTW, as someone who is quite familiar with the tungsten/halogen cycle,
I don't think the cycle temperature threshold has any effect here.
Jim Adney
>you have to use a special halogen dimmer which is engineered for halogen
>bulbs, the filament in the halogen has different chacteristics then a
>normal incandesent bulb and requires different electronic circuitry to
>properly maintain the required voltage and dim the bulb.
What's the difference? Both filaments are formed from a piece of
tungsten wire. Electrically there is very little difference. Has
anyone ever seen dimmers specifically made for halogen lamps?
If you have something specific in mind please tell us.
greg szekeres
>sparky <spa...@home.com> wrote:
>
>>you have to use a special halogen dimmer which is engineered for halogen
>>bulbs, the filament in the halogen has different chacteristics then a
>>normal incandesent bulb and requires different electronic circuitry to
>>properly maintain the required voltage and dim the bulb.
>
>What's the difference? Both filaments are formed from a piece of
>tungsten wire. Electrically there is very little difference. Has
>anyone ever seen dimmers specifically made for halogen lamps?
Looks like halogen filiments are shorter and probably have a wider
resistance spread between off an on since they run hotter.
greg
Georges
that is built through the wall above his oven shocks him when
he pulls the chain to turn it on. Checked with meter-1 probe
touching chain other probe touching ground and get a reading
of 120 volts. What would cause this problem?
Filip M. Gieszczykiewicz
Easy. Short to case. Take it out ASAP and trace the wires
until you find place where insulation is missing and wire
touches case. If he were ever to be touching the sink after
washing dishes and reach for the chain, you've got a 911
call on your hands since his heart will be between potential
and ground. Even if the floor is wet, he could be in deep shit.
Do NOT just replace the chain with a string. That's just
asking for trouble (tell him: no fix, maybe a trailer fire)..
that generally gets results. In this case, it's a _possibility_.
Cheers,
Filip G.
--
Filip "I'll buy a vowel" Gieszczykiewicz | http://www.repairfaq.org/
(fil...@corona.eps.pitt.edu)
I am the river itself and the leaf floating its currents.
I am steering. I am swept. I am.
Don Klipstein
Halogens usually have a filament temp. in the 2900's Kelvin and standard
incandescents usually run around 2700-2800. The difference is not much.
I suspect Sparky was thinking about electronic timers and photocontrols
for fluorescent lamps vs. such things for incandescent lamps.
- Don Klipstein (d...@misty.com)