Client wants to install some low-voltage halogens with a dimmer. Is this
OK? I know the dimmer will work, since the lamps are a resistive load,
but I'm not sure the halogens want to work on reduced voltage. Anyone
know for sure?


--
Just as McDonald's is where you go when you're hungry but don't really
care about the quality of your food, Wikipedia is where you go when
you're curious but don't really care about the quality of your knowledge.

- Matthew White's WikiWatch (http://users.erols.com/mwhite28/wikiwoo.htm)

David Nebenzahl spake thus:

Client wants to install some low-voltage halogens with a dimmer. Is
this OK? I know the dimmer will work, since the lamps are a resistive
load [...]

Doh! What was I thinking? *Not* a resistive load (transformer,
remember?) Never mind.

(Although I have successfully used ordinary dimmers with transformers
for some of my own projects, like a homebrew resistance soldering unit,
I'd never install one in anyone else's house.)


--
Just as McDonald's is where you go when you're hungry but don't really
care about the quality of your food, Wikipedia is where you go when
you're curious but don't really care about the quality of your knowledge.

- Matthew White's WikiWatch (http://users.erols.com/mwhite28/wikiwoo.htm)

David Nebenzahl wrote:
David Nebenzahl spake thus:

Client wants to install some low-voltage halogens with a dimmer. Is
this OK? I know the dimmer will work, since the lamps are a resistive
load [...]

Doh! What was I thinking? *Not* a resistive load (transformer,
remember?) Never mind.

(Although I have successfully used ordinary dimmers with transformers
for some of my own projects, like a homebrew resistance soldering
unit, I'd never install one in anyone else's house.)

You can dim low-voltage halogens, but I am not sure the standard over
the counter dimmer would be the best best, it will depend on your power
supply. However I suggest you consider the effect on a "halogen" lamp when
it is dimmed. After all they are designed to last longer using the halogen
cycle and that requires high heat. At any dimmed setting, the lamps are
likely not to go into a halogen cycle so the life expectancy may be cut
short.

--
Joseph Meehan

Dia 's Muire duit

"David Nebenzahl" wrote in message
.com...
Client wants to install some low-voltage halogens with a dimmer. Is this
OK? I know the dimmer will work, since the lamps are a resistive load,
but I'm not sure the halogens want to work on reduced voltage. Anyone
know for sure?


I have had many customers who chose low voltage lights become unhappy when
they decide to install dimmers. There is always a noise problem. Even with
a dimmer that is rated for magnetic or electronic power supplies there is
still some noise present depending on the light level. If they want to dim
the lights, don't use low voltage or install multiple switches to shut off
different areas to give a reduced light look.

I agree, if you want to dim them be sure to at least use electronic or
magnetic low voltage dimmers


"John Grabowski" wrote in message
...

"David Nebenzahl" wrote in message
.com...
Client wants to install some low-voltage halogens with a dimmer. Is this
OK? I know the dimmer will work, since the lamps are a resistive load,
but I'm not sure the halogens want to work on reduced voltage. Anyone
know for sure?


I have had many customers who chose low voltage lights become unhappy when
they decide to install dimmers. There is always a noise problem. Even
with
a dimmer that is rated for magnetic or electronic power supplies there is
still some noise present depending on the light level. If they want to
dim
the lights, don't use low voltage or install multiple switches to shut off
different areas to give a reduced light look.

"David Nebenzahl" wrote in message
.com...
Client wants to install some low-voltage halogens with a dimmer. Is this
OK? I know the dimmer will work, since the lamps are a resistive load, but
I'm not sure the halogens want to work on reduced voltage. Anyone know for
sure?


--
Just as McDonald's is where you go when you're hungry but don't really
care about the quality of your food, Wikipedia is where you go when
you're curious but don't really care about the quality of your knowledge.

- Matthew White's WikiWatch (http://users.erols.com/mwhite28/wikiwoo.htm)

Not a problem. There are a couple of things to know, however:

- Use the proper dimmer. Low voltage halogens require either a transformer
or electronic voltage reducer. Use a dimmer that's compatible with what
you're using.

- Halogens don't care if they are dimmed. At full power halogen lamps are
designed to utilize a tungsten recycling process which keeps the inside of
the bulb clean. The gas chemistry inside the bulb recycles the tungsten
that would ordinarily deposit on the bulb surface back onto the filament.
If you dim the lamp, the halogen cycle stops; but that's O.K. The filament
is operating at a lower temperature and not throwing off much tungsten
anyway. Some wonder if there is some kind of "forbidden zone" of
operation -- a dimmer setting where there is still filament evaporation, but
where the halogen cycle is not operating so the bulb darkens and perhaps
fails. According to the lamp engineers that I've talked to, that's
possible, but not likely in general lighting lamps. But if it should
happen, (you will be able to see the filament tube with a black deposit on
the inside surface) simply operate the lamp at full power for a few minutes
to restart the halogen cycle.

I have a house with several dimmer-controlled track lighting systems which
use numerous 120 volt PAR20 and 12 volt MR16 halogen lamps for downlighting,
accent lighting, etc. These systems are operated 6-10 hours/day at various
dimmer settings. I used transformer-powered fixtures for the MR16 lamps.
There is no noticeable noise, even when the dimmers are at the lowest
setting, unless the house is absolutely quiet (not a normal situation).
I've not had any 12 volt MR16 lamps fail during the 3+ years that the system
has been installed. The lamps have a life rating of 5000 or 6000 hours, so
I'm starting to expect a few failures.

The 120 volt PAR20 halogen lamps are very sensitive to physical shock. I've
had those fail when I simply adjust the fixture and happen to shake the
fixture. What happens is that some filament coils short together and put
too much voltage on the rest of the filament. (you can see the filament
move when you look at the light beam). Now, I dim the lamp and move the
fixture very carefully and replace lamps with the power off.

TKM

readandpostrosie wrote:
SPEAKING OF dimmers........................when will they work with
the new florescent lights?

Depends on the dimmer and the lamp.

--
Joseph Meehan

Dia 's Muire duit

SPEAKING OF dimmers........................when will they work with the new
florescent lights?

--

readandpostrosie spake thus:

SPEAKING OF dimmers........................when will they work with the new
florescent lights?

Good question. So far as I know, that would require a complete redesign
of the electronics which drive the lamps, which now require a sufficient
voltage to operate at all. Theoretically possible, just depends on
economic factors.

BTW, speaking of compact fluorescents, what are they going for in your
locale? Here (S.F. Bay Area), cheap bulbs pop up from time to time at
various places, subsidized by the local greedy monopoly^H^H^H^H^Hutility
company, PG&E. Currently, Al Lasher's Electronics in Berkeley is selling
the nice bright 23 watt "twisted" lamps (100 watt equivalent light
output) for $1.25 each. The next best deal seems to be at Home Despot,
which is selling 4-packs of the same bulbs for about $10.


--
Just as McDonald's is where you go when you're hungry but don't really
care about the quality of your food, Wikipedia is where you go when
you're curious but don't really care about the quality of your knowledge.

- Matthew White's WikiWatch (http://users.erols.com/mwhite28/wikiwoo.htm)

Many of the low voltage halogen lights
us an "electronic" transformer. It
is actually an electronic power supply
running a transformer at a higher
frequency than 60Hz ... the higher the
frequency, the less iron needed in
the transformer, making it smaller and
lighter. Some of these may be dimmed,
some not. You have to check the specs
on the unit. Also, you probably need
a dimmer which can be used for this
application, as the load seen by the dimmer,
is not purely a lamp filament. BTW, I
have 2 strings of 20 watt hockey puck
lights running from 2 electronic
transformers and dimmed by an electronic
dimmer with no problems. Both dimmer
and "transformers" were rated for
each other.

TKM wrote:
"David Nebenzahl" wrote in message
.com...
Client wants to install some low-voltage halogens with a dimmer. Is this
OK? I know the dimmer will work, since the lamps are a resistive load, but
I'm not sure the halogens want to work on reduced voltage. Anyone know for
sure?


--
Just as McDonald's is where you go when you're hungry but don't really
care about the quality of your food, Wikipedia is where you go when
you're curious but don't really care about the quality of your knowledge.

- Matthew White's WikiWatch (http://users.erols.com/mwhite28/wikiwoo.htm)

Not a problem. There are a couple of things to know, however:

- Use the proper dimmer. Low voltage halogens require either a transformer
or electronic voltage reducer. Use a dimmer that's compatible with what
you're using.

- Halogens don't care if they are dimmed. At full power halogen lamps are
designed to utilize a tungsten recycling process which keeps the inside of
the bulb clean. The gas chemistry inside the bulb recycles the tungsten
that would ordinarily deposit on the bulb surface back onto the filament.
If you dim the lamp, the halogen cycle stops; but that's O.K. The filament
is operating at a lower temperature and not throwing off much tungsten
anyway. Some wonder if there is some kind of "forbidden zone" of
operation -- a dimmer setting where there is still filament evaporation, but
where the halogen cycle is not operating so the bulb darkens and perhaps
fails. According to the lamp engineers that I've talked to, that's
possible, but not likely in general lighting lamps. But if it should
happen, (you will be able to see the filament tube with a black deposit on
the inside surface) simply operate the lamp at full power for a few minutes
to restart the halogen cycle.

I have a house with several dimmer-controlled track lighting systems which
use numerous 120 volt PAR20 and 12 volt MR16 halogen lamps for downlighting,
accent lighting, etc. These systems are operated 6-10 hours/day at various
dimmer settings. I used transformer-powered fixtures for the MR16 lamps.
There is no noticeable noise, even when the dimmers are at the lowest
setting, unless the house is absolutely quiet (not a normal situation).
I've not had any 12 volt MR16 lamps fail during the 3+ years that the system
has been installed. The lamps have a life rating of 5000 or 6000 hours, so
I'm starting to expect a few failures.

The 120 volt PAR20 halogen lamps are very sensitive to physical shock. I've
had those fail when I simply adjust the fixture and happen to shake the
fixture. What happens is that some filament coils short together and put
too much voltage on the rest of the filament. (you can see the filament
move when you look at the light beam). Now, I dim the lamp and move the
fixture very carefully and replace lamps with the power off.

TKM

David Nebenzahl wrote:
readandpostrosie spake thus:

SPEAKING OF dimmers........................when will they work with
the new florescent lights?

Good question. So far as I know, that would require a complete redesign
of the electronics which drive the lamps, which now require a sufficient
voltage to operate at all. Theoretically possible, just depends on
economic factors.

BTW, speaking of compact fluorescents, what are they going for in your
locale? Here (S.F. Bay Area), cheap bulbs pop up from time to time at
various places, subsidized by the local greedy monopoly^H^H^H^H^Hutility
company, PG&E. Currently, Al Lasher's Electronics in Berkeley is selling
the nice bright 23 watt "twisted" lamps (100 watt equivalent light
output) for $1.25 each. The next best deal seems to be at Home Despot,
which is selling 4-packs of the same bulbs for about $10.

Some CFLs are rated to be dimmed, most
are not. Read the packaging int
the store. Usually, the dimmable CFLs
are a little more pricey.

Our track lighting uses a special dimmer designed for this purpose.
Additionally it uses a high tech transformer (essentially converts line
input to high frequency so it can use a smaller transformer). I just went
to a lighting store and they sold me the appropriate stuff. NOT CHEAP but
lights etc were what the wife wanted.


"TKM" wrote in message
...

"David Nebenzahl" wrote in message
.com...
Client wants to install some low-voltage halogens with a dimmer. Is this
OK? I know the dimmer will work, since the lamps are a resistive load,
but I'm not sure the halogens want to work on reduced voltage. Anyone
know for sure?


--
Just as McDonald's is where you go when you're hungry but don't really
care about the quality of your food, Wikipedia is where you go when
you're curious but don't really care about the quality of your knowledge.

- Matthew White's WikiWatch (http://users.erols.com/mwhite28/wikiwoo.htm)

Not a problem. There are a couple of things to know, however:

- Use the proper dimmer. Low voltage halogens require either a
transformer or electronic voltage reducer. Use a dimmer that's compatible
with what you're using.

- Halogens don't care if they are dimmed. At full power halogen lamps are
designed to utilize a tungsten recycling process which keeps the inside of
the bulb clean. The gas chemistry inside the bulb recycles the tungsten
that would ordinarily deposit on the bulb surface back onto the filament.
If you dim the lamp, the halogen cycle stops; but that's O.K. The
filament is operating at a lower temperature and not throwing off much
tungsten anyway. Some wonder if there is some kind of "forbidden zone" of
operation -- a dimmer setting where there is still filament evaporation,
but where the halogen cycle is not operating so the bulb darkens and
perhaps fails. According to the lamp engineers that I've talked to,
that's possible, but not likely in general lighting lamps. But if it
should happen, (you will be able to see the filament tube with a black
deposit on the inside surface) simply operate the lamp at full power for a
few minutes to restart the halogen cycle.

I have a house with several dimmer-controlled track lighting systems which
use numerous 120 volt PAR20 and 12 volt MR16 halogen lamps for
downlighting, accent lighting, etc. These systems are operated 6-10
hours/day at various dimmer settings. I used transformer-powered fixtures
for the MR16 lamps. There is no noticeable noise, even when the dimmers
are at the lowest setting, unless the house is absolutely quiet (not a
normal situation). I've not had any 12 volt MR16 lamps fail during the 3+
years that the system has been installed. The lamps have a life rating of
5000 or 6000 hours, so I'm starting to expect a few failures.

The 120 volt PAR20 halogen lamps are very sensitive to physical shock.
I've had those fail when I simply adjust the fixture and happen to shake
the fixture. What happens is that some filament coils short together and
put too much voltage on the rest of the filament. (you can see the
filament move when you look at the light beam). Now, I dim the lamp and
move the fixture very carefully and replace lamps with the power off.

TKM

Well said TKM!

Dimmer quality is big factor in the noise issue as well.
(So many myths, so little time...)

Richard Reid, LC