Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

john stone forklarede:
Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

A bit dimmer?

If the resistance of the lamp was independent of the temperature, which
it is not, the lamp would draw 1/2 the current at 1/2 the voltage,
giving 1/4 the wattage, 2.5w.

However, the resistance _is_ dependent of the temperature. Se more at

http://en.wikipedia.org/wiki/Halogen...on_performance

But the bottom line: Nothing will fail catastropically, but you may get
much less light than expected. But it may look nice and christmassy :-)

Leif
(with a lot of but's ;-))

--
Husk kørelys bagpå, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.

john stone wrote:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

A halogen lamp on the correct voltage runs the filament hotter than a
standard incandescent tungsten lamp. Without the halogen gas filling,
this would soon cause the tungsten to migrate from the filament to the
inside of the bulb, where it would blacken the glass. The filament
would rapidly become thin and then would break.

At a certain temperature, the halogen will combine with the tungsten on
the inside of the glass. It then floats around until it meets the hot
filament, where it deposits the tungsten back where it came from
(approximately). This depends on having the glass hot enough to allow
the halogen and tungsten to combine, which occurs at near dull-red heat
(which is why quartz glass is necessary).

If you under-run the lamp, the filament will not blacken the glass as
quickly, but the glass will not reach recycling temperature, so any
blackening will remain. The relative temperatures of the filament and
glass will determine whether the life if the lamp is extended or
shortened. The light output will be very muchreduced and lacking the
blue end of the spectrum.

--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

To put it a bit more simply...

A /slight/ reduction in voltage will cause a halogen lamp to burn out
prematurely, because the bulb doesn't get hot enough to initiate the
"recycling" process -- but the filament is still extremely hot.

Half voltage is a huge drop. You should have no problems.

On Tue, 11 Dec 2012 12:47:53 -0000, "john stone"
wrote:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

At 6V the halogen cycle won't operate so you'll probably get
discoloration of the bulb after some time and perhaps the bulb won't
last as long (to the degree that it's a trade-off of lower power vs.
the elimination of the halogen cycle). Other than that, it'll
probably be a very yellow light at pretty low intensity.

On Tue, 11 Dec 2012 10:17:58 -0500, z wrote:

On Tue, 11 Dec 2012 12:47:53 -0000, "john stone"
wrote:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

At 6V the halogen cycle won't operate so you'll probably get
discoloration of the bulb after some time and perhaps the bulb won't
last as long (to the degree that it's a trade-off of lower power vs.
the elimination of the halogen cycle). Other than that, it'll
probably be a very yellow light at pretty low intensity.

We run a halogen (over our dinner table) from a dimmer. We seldom use it at full
brightness. It's about 10 years old and still on the original bulb.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

On Tue, 11 Dec 2012 08:35:17 -0800, John Larkin
wrote:

On Tue, 11 Dec 2012 10:17:58 -0500, z wrote:

On Tue, 11 Dec 2012 12:47:53 -0000, "john stone"
wrote:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

At 6V the halogen cycle won't operate so you'll probably get
discoloration of the bulb after some time and perhaps the bulb won't
last as long (to the degree that it's a trade-off of lower power vs.
the elimination of the halogen cycle). Other than that, it'll
probably be a very yellow light at pretty low intensity.

We run a halogen (over our dinner table) from a dimmer. We seldom use it at full
brightness. It's about 10 years old and still on the original bulb.

The envelope is probably black by now. Incandescent life goes with
something like the 12th power of, er, power, so it's not surprising.
You'll probably find that it won't last all that long, now, at full
power. It's filament is now on the inside of the envelope.

We run a halogen (over our dinner table) from a dimmer.
We seldom use it at full brightness. It's about 10 years old
and still on the original bulb.

The envelope is probably black by now. Incandescent life goes with
something like the 12th power of, er, power, so it's not surprising.
You'll probably find that it won't last all that long, now, at full
power. Its filament is now on the inside of the envelope.

Actually, it's the 12th power of voltage.

Even a slight drop in voltage causes a big increase in life. For example, a
5% reduction almost doubles the lamp's life (1.85 times). At a 10%
reduction, the lamp lasts 3.5 times as long.

On Tue, 11 Dec 2012 09:18:37 -0800, "William Sommerwerck"
wrote:

We run a halogen (over our dinner table) from a dimmer.
We seldom use it at full brightness. It's about 10 years old
and still on the original bulb.

The envelope is probably black by now. Incandescent life goes with
something like the 12th power of, er, power, so it's not surprising.
You'll probably find that it won't last all that long, now, at full
power. Its filament is now on the inside of the envelope.

Actually, it's the 12th power of voltage.

Of course.

Even a slight drop in voltage causes a big increase in life. For example, a
5% reduction almost doubles the lamp's life (1.85 times). At a 10%
reduction, the lamp lasts 3.5 times as long.

"john stone" wrote in
:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But
the mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences
running at the lower voltage? Thanks.



Halogen has a build in cycle to keep the filament healthy.
That does not work at a lower temperature.
So running it at the wrong voltage will cause it to fail
early.
Other then that, for a decoration a dim bulb is no problem,

On Tue, 11 Dec 2012 12:04:13 -0500, z wrote:

On Tue, 11 Dec 2012 08:35:17 -0800, John Larkin
wrote:

On Tue, 11 Dec 2012 10:17:58 -0500, z wrote:

On Tue, 11 Dec 2012 12:47:53 -0000, "john stone"
wrote:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

At 6V the halogen cycle won't operate so you'll probably get
discoloration of the bulb after some time and perhaps the bulb won't
last as long (to the degree that it's a trade-off of lower power vs.
the elimination of the halogen cycle). Other than that, it'll
probably be a very yellow light at pretty low intensity.

We run a halogen (over our dinner table) from a dimmer. We seldom use it at full
brightness. It's about 10 years old and still on the original bulb.

The envelope is probably black by now.

No. Why should it be, if we seldom run it full brightness? Filamant evaporation
goes as some insane power of voltage. And when we do occasionally run it at full
voltage, won't the halogen cycle do its thing?


Incandescent life goes with
something like the 12th power of, er, power, so it's not surprising.


Exactly. Running it at half voltage, or even 3/4 voltage, is almost equivalent
to turning it completely off.

Various references say that incensescent lifetime goes as voltage to the -13 to
-16 power.

You'll probably find that it won't last all that long, now, at full
power. It's filament is now on the inside of the envelope.

Can't see why. The evaporation rate is 0.5^13 as much at half voltage as at
full. That's essentially no evaporation at all.

Anyhow, it's over 10 years old and works fine. I may never get to use that spare
bulb.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

"John Larkin"


Various references say that incensescent lifetime goes as voltage to
the -13 to
-16 power.


** The formula that predicts lamp life is only valid for a small range
around the nominal voltage, about 10%. The simplifying assumptions it is
based on are true only in this range.

Reducing the voltage by large percentages extends lamp life by factor of 10
or possibly up to 100 - the halogen cycle has SFA to do with it.


.... Phil

On Tue, 11 Dec 2012 09:18:37 -0800, "William Sommerwerck"
wrote:

We run a halogen (over our dinner table) from a dimmer.
We seldom use it at full brightness. It's about 10 years old
and still on the original bulb.

The envelope is probably black by now. Incandescent life goes with
something like the 12th power of, er, power, so it's not surprising.
You'll probably find that it won't last all that long, now, at full
power. Its filament is now on the inside of the envelope.

Actually, it's the 12th power of voltage.

Even a slight drop in voltage causes a big increase in life. For example, a
5% reduction almost doubles the lamp's life (1.85 times). At a 10%
reduction, the lamp lasts 3.5 times as long.

I guess the question becomes: is there some voltage a bit below normal, where
the halogen cycle doesn't work and lamp life actually degrades? I'm guessing no.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

On 11 Dec 2012 18:19:51 GMT, Sjouke Burry s@b wrote:

"john stone" wrote in
:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But
the mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences
running at the lower voltage? Thanks.



Halogen has a build in cycle to keep the filament healthy.
That does not work at a lower temperature.
So running it at the wrong voltage will cause it to fail
early.

Why? If there is almost no filament evaporation (which is the case at, say, half
or 3/4 voltage) why would it fail sooner? The halogen thing might not kick in at
low voltage, but then it's not needed.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

Even a slight drop in voltage causes a big increase in life. For example,
a 5% reduction almost doubles the lamp's life (1.85 times). At a 10%
reduction, the lamp lasts 3.5 times as long.

I guess the question becomes: is there some voltage a bit below normal,
where the halogen cycle doesn't work and lamp life actually degrades?
I'm guessing no.

I'm guessing yes. A friend had halogen lamps on a dimmer, which he dimmed
only slightly -- and they burned out pretty quickly.

The halogen cycle requires a very high temperature. Ergo...

On Tue, 11 Dec 2012 21:47:27 -0800, John Larkin
wrote:

On Tue, 11 Dec 2012 12:04:13 -0500, z wrote:

On Tue, 11 Dec 2012 08:35:17 -0800, John Larkin
wrote:

On Tue, 11 Dec 2012 10:17:58 -0500, z wrote:

On Tue, 11 Dec 2012 12:47:53 -0000, "john stone"
wrote:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

At 6V the halogen cycle won't operate so you'll probably get
discoloration of the bulb after some time and perhaps the bulb won't
last as long (to the degree that it's a trade-off of lower power vs.
the elimination of the halogen cycle). Other than that, it'll
probably be a very yellow light at pretty low intensity.

We run a halogen (over our dinner table) from a dimmer. We seldom use it at full
brightness. It's about 10 years old and still on the original bulb.

The envelope is probably black by now.

No. Why should it be, if we seldom run it full brightness?

Because you DON'T run it at full brightness the envelope isn't cleared
by the halogen cycle. This is a common failure of halogen bulbs. They
get black, reducing their light output and fail early.

Filamant evaporation
goes as some insane power of voltage. And when we do occasionally run it at full
voltage, won't the halogen cycle do its thing?

But you just said you rarely run it at full power. It can't if you
don't.

Incandescent life goes with
something like the 12th power of, er, power, so it's not surprising.


Exactly. Running it at half voltage, or even 3/4 voltage, is almost equivalent
to turning it completely off.

s/power/voltage, as pointed out earlier.

Various references say that incensescent lifetime goes as voltage to the -13 to
-16 power.

12/16, who's counting.

You'll probably find that it won't last all that long, now, at full
power. It's filament is now on the inside of the envelope.

Can't see why. The evaporation rate is 0.5^13 as much at half voltage as at
full. That's essentially no evaporation at all.

The halogen cycle stops.

Anyhow, it's over 10 years old and works fine. I may never get to use that spare
bulb.

There are carbon filament bulbs still operating from a hundred years
ago. shrug

On 12/11/2012 12:18 PM, William Sommerwerck wrote:
We run a halogen (over our dinner table) from a dimmer.
We seldom use it at full brightness. It's about 10 years old
and still on the original bulb.

The envelope is probably black by now. Incandescent life goes with
something like the 12th power of, er, power, so it's not surprising.
You'll probably find that it won't last all that long, now, at full
power. Its filament is now on the inside of the envelope.

Actually, it's the 12th power of voltage.

Even a slight drop in voltage causes a big increase in life. For
example, a 5% reduction almost doubles the lamp's life (1.85 times). At
a 10% reduction, the lamp lasts 3.5 times as long.

It's all a curve fitting exercise, and V**12 looks a lot like V**10.(*)
It's often quoted as going like exp(10500/T(K)), where T is the
filament temperature, which goes roughly like sqrt(V). That's a
slightly more physicsy fitting function, but none of them work very well
over any wide voltage range. For instance, the lifetime increase at 10%
below rated voltage is variously quoted anywhere from 3x to 5x.

Cheers

Phil Hobbs


(*) Which is why the Hilbert matrix is so ill-conditioned.

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

On 12/12/2012 12:55 AM, John Larkin wrote:
On Tue, 11 Dec 2012 09:18:37 -0800, "William Sommerwerck"
wrote:

We run a halogen (over our dinner table) from a dimmer.
We seldom use it at full brightness. It's about 10 years old
and still on the original bulb.

The envelope is probably black by now. Incandescent life goes with
something like the 12th power of, er, power, so it's not surprising.
You'll probably find that it won't last all that long, now, at full
power. Its filament is now on the inside of the envelope.

Actually, it's the 12th power of voltage.

Even a slight drop in voltage causes a big increase in life. For example, a
5% reduction almost doubles the lamp's life (1.85 times). At a 10%
reduction, the lamp lasts 3.5 times as long.

I guess the question becomes: is there some voltage a bit below normal, where
the halogen cycle doesn't work and lamp life actually degrades? I'm guessing no.



The bulb envelope cleans up if you run it at full power for awhile anyway.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

On 12/11/2012 01:19 PM, Sjouke Burry wrote:
"john wrote in
:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But
the mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences
running at the lower voltage? Thanks.



Halogen has a build in cycle to keep the filament healthy.
That does not work at a lower temperature.
So running it at the wrong voltage will cause it to fail
early.
Other then that, for a decoration a dim bulb is no problem,

Nope. The halogen cycle is to keep the envelope clean. The high gas
pressure extends the filament life, by causing tungsten to be
selectively redeposited back on the same hotspots it came from.
Otherwise the tungsten redeposits randomly, and there's nothing to keep
the hotspots from necking down and failing just as early as in a
low-pressure bulb.

(We keep coming back to this every few months lately.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

John Larkin wrote:
On Tue, 11 Dec 2012 10:17:58 -0500, z wrote:

On Tue, 11 Dec 2012 12:47:53 -0000, "john stone"
wrote:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

At 6V the halogen cycle won't operate so you'll probably get
discoloration of the bulb after some time and perhaps the bulb won't
last as long (to the degree that it's a trade-off of lower power vs.
the elimination of the halogen cycle). Other than that, it'll
probably be a very yellow light at pretty low intensity.

We run a halogen (over our dinner table) from a dimmer. We seldom use it at full
brightness. It's about 10 years old and still on the original bulb.


I got some in my kitchen, range hood, bathroom. I have never experienced
problems on dimmer. Most of the bulbs last long, but you get one occasional
early failure. Except for the range hood which is run full on or full dim,
the others lights are most always run 1/2 to 3/4 brightness.

Greg

On Wed, 12 Dec 2012 05:32:08 -0800, "William Sommerwerck"
wrote:

Even a slight drop in voltage causes a big increase in life. For example,
a 5% reduction almost doubles the lamp's life (1.85 times). At a 10%
reduction, the lamp lasts 3.5 times as long.

I guess the question becomes: is there some voltage a bit below normal,
where the halogen cycle doesn't work and lamp life actually degrades?
I'm guessing no.

I'm guessing yes. A friend had halogen lamps on a dimmer, which he dimmed
only slightly -- and they burned out pretty quickly.

The halogen cycle requires a very high temperature. Ergo...

If there's almost no filament evaporation, who cares if the halogen cycle isn't
working? It's not needed. And it will work if full line voltage is applied
occasionally.

Our kitchen-table halogen is dimmed and is over 10 years old, on the original
bulb.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

On Wed, 12 Dec 2012 09:01:59 -0500, z wrote:

On Tue, 11 Dec 2012 21:47:27 -0800, John Larkin
wrote:

On Tue, 11 Dec 2012 12:04:13 -0500, z wrote:

On Tue, 11 Dec 2012 08:35:17 -0800, John Larkin
wrote:

On Tue, 11 Dec 2012 10:17:58 -0500, z wrote:

On Tue, 11 Dec 2012 12:47:53 -0000, "john stone"
wrote:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

At 6V the halogen cycle won't operate so you'll probably get
discoloration of the bulb after some time and perhaps the bulb won't
last as long (to the degree that it's a trade-off of lower power vs.
the elimination of the halogen cycle). Other than that, it'll
probably be a very yellow light at pretty low intensity.

We run a halogen (over our dinner table) from a dimmer. We seldom use it at full
brightness. It's about 10 years old and still on the original bulb.

The envelope is probably black by now.

No. Why should it be, if we seldom run it full brightness?

Because you DON'T run it at full brightness the envelope isn't cleared
by the halogen cycle. This is a common failure of halogen bulbs. They
get black, reducing their light output and fail early.

If there's hardly any evaporation, why would the bulb get black?

Our dimmed halogen isn't black. And it's run for a couple of hours per day for
10 years now.



Filamant evaporation
goes as some insane power of voltage. And when we do occasionally run it at full
voltage, won't the halogen cycle do its thing?

But you just said you rarely run it at full power. It can't if you
don't.

Are you now debating the difference between "rarely" and "occasionally"?



--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

On Thu, 13 Dec 2012 09:15:28 -0800, John Larkin
wrote:

On Wed, 12 Dec 2012 09:01:59 -0500, z wrote:

On Tue, 11 Dec 2012 21:47:27 -0800, John Larkin
wrote:

On Tue, 11 Dec 2012 12:04:13 -0500, z wrote:

On Tue, 11 Dec 2012 08:35:17 -0800, John Larkin
wrote:

On Tue, 11 Dec 2012 10:17:58 -0500, z wrote:

On Tue, 11 Dec 2012 12:47:53 -0000, "john stone"
wrote:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

At 6V the halogen cycle won't operate so you'll probably get
discoloration of the bulb after some time and perhaps the bulb won't
last as long (to the degree that it's a trade-off of lower power vs.
the elimination of the halogen cycle). Other than that, it'll
probably be a very yellow light at pretty low intensity.

We run a halogen (over our dinner table) from a dimmer. We seldom use it at full
brightness. It's about 10 years old and still on the original bulb.

The envelope is probably black by now.

No. Why should it be, if we seldom run it full brightness?

Because you DON'T run it at full brightness the envelope isn't cleared
by the halogen cycle. This is a common failure of halogen bulbs. They
get black, reducing their light output and fail early.

If there's hardly any evaporation, why would the bulb get black?

A faulty assumption doesn't bode well for any conclusions drawn.

Our dimmed halogen isn't black. And it's run for a couple of hours per day for
10 years now.

It must be *really* dimmed, unless it's also run for some hours at
full power. Every halogen I've dimmed has turned black after some
time.


Filamant evaporation
goes as some insane power of voltage. And when we do occasionally run it at full
voltage, won't the halogen cycle do its thing?

But you just said you rarely run it at full power. It can't if you
don't.

Are you now debating the difference between "rarely" and "occasionally"?

It makes a difference.

"John Larkin" wrote in message
...
On Wed, 12 Dec 2012 05:32:08 -0800, "William Sommerwerck"
wrote:

Even a slight drop in voltage causes a big increase in life. For
example,
a 5% reduction almost doubles the lamp's life (1.85 times). At a 10%
reduction, the lamp lasts 3.5 times as long.

I guess the question becomes: is there some voltage a bit below normal,
where the halogen cycle doesn't work and lamp life actually degrades?
I'm guessing no.

I'm guessing yes. A friend had halogen lamps on a dimmer, which
he dimmed only slightly -- and they burned out pretty quickly.
The halogen cycle requires a very high temperature. Ergo...

If there's almost no filament evaporation, who cares if the halogen
cycle isn't working? It's not needed. And it will work if full line
voltage
is applied occasionally.

Does anyone ACTUALLY READ WHAT IS POSTED? And THINK about it? Why is it
necessary to explain something in excruciating detail over and over and over
again?

"William Sommerwerck"
"John Larkin"
"William Sommerwerck"


I'm guessing yes. A friend had halogen lamps on a dimmer, which
he dimmed only slightly -- and they burned out pretty quickly.
The halogen cycle requires a very high temperature. Ergo...

If there's almost no filament evaporation, who cares if the halogen
cycle isn't working? It's not needed. And it will work if full line
voltage is applied occasionally.

Does anyone ACTUALLY READ WHAT IS POSTED? And THINK about it?


** John has done that and written an excellent reply.

How about YOU read it and THINK about it -

instead of childishly stamping your stupid fat feet all over the place.



..... Phil

"Phil Allison" wrote in message ...
"William Sommerwerck"
"John Larkin"
"William Sommerwerck"

I'm guessing yes. A friend had halogen lamps on a dimmer, which
he dimmed only slightly -- and they burned out pretty quickly.
The halogen cycle requires a very high temperature. Ergo...

If there's almost no filament evaporation, who cares if the halogen
cycle isn't working? It's not needed. And it will work if full line
voltage is applied occasionally.

Does anyone ACTUALLY READ WHAT IS POSTED? And THINK about it?


** John has done that and written an excellent reply.
How about YOU read it and THINK about it --
instead of childishly stamping your stupid fat feet all over the place.


If you'd been paying attention, you'd have seen that his most-recent remark
(above), though correct /out of context/, has nothing to do with the issue
at hand.

On Thu, 13 Dec 2012 10:37:08 -0800, "William Sommerwerck"
wrote:

"John Larkin" wrote in message
.. .
On Wed, 12 Dec 2012 05:32:08 -0800, "William Sommerwerck"
wrote:

Even a slight drop in voltage causes a big increase in life. For
example,
a 5% reduction almost doubles the lamp's life (1.85 times). At a 10%
reduction, the lamp lasts 3.5 times as long.

I guess the question becomes: is there some voltage a bit below normal,
where the halogen cycle doesn't work and lamp life actually degrades?
I'm guessing no.

I'm guessing yes. A friend had halogen lamps on a dimmer, which
he dimmed only slightly -- and they burned out pretty quickly.
The halogen cycle requires a very high temperature. Ergo...

If there's almost no filament evaporation, who cares if the halogen
cycle isn't working? It's not needed. And it will work if full line
voltage
is applied occasionally.

Does anyone ACTUALLY READ WHAT IS POSTED? And THINK about it? Why is it
necessary to explain something in excruciating detail over and over and over
again?

Because people keep making the same illogical claims?


--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation

"William Sommerwerck""

I'm guessing yes. A friend had halogen lamps on a dimmer, which
he dimmed only slightly -- and they burned out pretty quickly.
The halogen cycle requires a very high temperature. Ergo...

If there's almost no filament evaporation, who cares if the halogen
cycle isn't working? It's not needed. And it will work if full line
voltage is applied occasionally.

Does anyone ACTUALLY READ WHAT IS POSTED? And THINK about it?


** John has done that and written an excellent reply.
How about YOU read it and THINK about it --
instead of childishly stamping your stupid fat feet all over the place.


If you'd been paying attention, you'd have seen that his most-recent
remark (above), though correct /out of context/, has nothing to do with
the issue at hand.

** What "issue" is that ??

"Phil Allison" wrote in message ...
"William Sommerwerck""

If you'd been paying attention, you'd have seen that his most-recent
remark (above), though correct /out of context/, has nothing to do with
the issue at hand.

** What "issue" is that ??

There are actually two issues.

One... A halogen lamp has to run at or above the temperature at which the
tungsten is redeposited on the filament more rapidly than it evaporates.
This temperature is presumably well-above the temperature of a conventional
incandescent lamp. It's reasonable to assume that reducing the filament
voltage some unstated amount will lower the temperature below the critical
recycling temperature, but still high enough to cause the filament to
rapidly burn out. No one here seems to have any information about this.

Two... "Obviously", if the filament voltage is "low enough", the rate of
tungsten evaporation will be so low, that it doesn't matter whether the lamp
is conventional or halogen.

These have nothing to do with each other, as the temperature for One is
almost certainly well above the temperature for Two.

This is what Wikipedia has to say. (The following is 100% accurate and
unimpeachable, of course.)

"Halogen lamps are manufactured with enough halogen to match the rate of
tungsten evaporation at their design voltage. Increasing the applied voltage
increases the rate of evaporation, so at some point there may be
insufficient halogen and the lamp goes black. Over-voltage operation is not
generally recommended. With a reduced voltage the evaporation is lower and
there may be too much halogen, which can lead to abnormal failure. At much
lower voltages, the bulb temperature may be too low to support the halogen
cycle, but by this time the evaporation rate is too low for the bulb to
blacken significantly. There are many situations where halogen lamps are
dimmed successfully. However, lamp life may not be extended as much as
predicted. The life span on dimming depends on lamp construction, the
halogen additive used and whether dimming is normally expected for this
type."

The article says that the first halogen lamps (for a carbon filament) were
patented in 1882.

On Fri, 14 Dec 2012 05:37:44 -0800, "William Sommerwerck"
wrote:

"Phil Allison" wrote in message ...
"William Sommerwerck""

If you'd been paying attention, you'd have seen that his most-recent
remark (above), though correct /out of context/, has nothing to do with
the issue at hand.

** What "issue" is that ??

There are actually two issues.

One... A halogen lamp has to run at or above the temperature at which the
tungsten is redeposited on the filament more rapidly than it evaporates.
This temperature is presumably well-above the temperature of a conventional
incandescent lamp. It's reasonable to assume that reducing the filament
voltage some unstated amount

The title of this thread is "Running at half the voltage."


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

"William Sommerwerck"
"Phil Allison"

** What "issue" is that ??

There are actually two issues.

One... A halogen lamp has to run at or above the temperature at which the
tungsten is redeposited on the filament more rapidly than it evaporates.


** Irrelevant.

The TRUTH is that the re-deposited metal does NOT repair the damage done to
the filament - there are many pics that show this.

The halogen cycle merely keeps the quartz glass clean !!


This temperature is presumably well-above the temperature of a
conventional incandescent lamp. It's reasonable to assume that reducing
the filament voltage some unstated amount will lower the temperature below
the critical recycling temperature, but still high enough to cause the
filament to rapidly burn out. No one here seems to have any information
about this.


** The simple fact is that halogen lamps do NOT have especially long lives -
any more than non halogen lamps with the same filaments.

"Halogen lamps are manufactured with enough halogen to match the rate of
tungsten evaporation at their design voltage. Increasing the applied
voltage increases the rate of evaporation, so at some point there may be
insufficient halogen and the lamp goes black.

** See - it is all about the darn glass.


Over-voltage operation is not generally recommended. With a reduced
voltage the evaporation is lower and there may be too much halogen, which
can lead to abnormal failure.

** Note weasel words.

At much lower voltages, the bulb temperature may be too low to support the
halogen cycle, but by this time the evaporation rate is too low for the
bulb to blacken significantly.

** Still all about the darn glass.


There are many situations where halogen lamps are dimmed successfully.

** Not many - ALL !!

However, lamp life may not be extended as much as predicted.

** The predicted life extension ( power of 12 or 14 ) is not usable beyond
about 10% voltage reduction as the numbers become huge.


The life span on dimming depends on lamp construction

** Yep.

And the one thing that matters most is the GAUGE of the wire in the
filament.

Most halogen lamps are LOW voltage, hence THICK filaments - leading to
longer life than for high voltage ( ie 120V /240V) lamps of the same power.

It is sooooooo simple - if the surface temp is the same but there is way
more material then it takes longer for the filament to wear out.


..... Phil

On 12/14/2012 5:56 PM, Phil Allison wrote:

"William Sommerwerck"
"Phil Allison"

** What "issue" is that ??

There are actually two issues.

One... A halogen lamp has to run at or above the temperature at which the
tungsten is redeposited on the filament more rapidly than it evaporates.


** Irrelevant.

The TRUTH is that the re-deposited metal does NOT repair the damage done to
the filament - there are many pics that show this.

The halogen cycle merely keeps the quartz glass clean !!


This temperature is presumably well-above the temperature of a
conventional incandescent lamp. It's reasonable to assume that reducing
the filament voltage some unstated amount will lower the temperature below
the critical recycling temperature, but still high enough to cause the
filament to rapidly burn out. No one here seems to have any information
about this.


** The simple fact is that halogen lamps do NOT have especially long lives -
any more than non halogen lamps with the same filaments.

You're right about the halogen being there to keep the glass clean, but
not about the longer life. A 3400K mogul-base photoflood, like the ones
I used to use in the 1970s, has a lifetime of about 25 hours.

The high gas pressure inside quartz-halogen bulbs is what requires the
very thick quartz envelopes. High pressure slows down the diffusion of
tungsten vapour away from the hot spots, so that metal is selectively
redeposited near where it evaporated. That improves the lifetime by a
pretty useful factor like 20, and that's apples-to-apples, both 120V 500W.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058

hobbs at electrooptical dot net
http://electrooptical.net

"Phil Hobbs"
Phil Allison wrote:


** The simple fact is that halogen lamps do NOT have especially long
lives -
any more than non halogen lamps with the same filaments.

You're right about the halogen being there to keep the glass clean, but
not about the longer life. A 3400K mogul-base photoflood, like the ones I
used to use in the 1970s, has a lifetime of about 25 hours.

** Really ?

What is that supposed to prove ? ?

Is that not a 120V quartz-halogen lamp ???

A 24V, 150W, 3300K QI ( 35mm slide) projector lamp has a rated life of 50
hours.

Such lamps have been in use common since the late 1960s.


The high gas pressure inside quartz-halogen bulbs is what requires the
very thick quartz envelopes. High pressure slows down the diffusion of
tungsten vapour away from the hot spots, so that metal is selectively
redeposited near where it evaporated.


** ROTFL.

It is NOT in the SAME places and huge gaps open up.

See the pics on Wiki.



..... Phil

There are many situations where halogen lamps are dimmed successfully.

** Not many - ALL !!

I won't gainsay any of your other remarks. But I've seen this.

"William Sommerwerck"

There are many situations where halogen lamps are dimmed successfully.

** Not many - ALL !!

I won't gainsay any of your other remarks. But I've seen this.


** Maybe you have seen a QI lamp fail early - so have I.

Proves nothing.



..... Phil

On 12/14/2012 10:32 PM, Phil Allison wrote:
"Phil Hobbs"
Phil Allison wrote:


** The simple fact is that halogen lamps do NOT have especially long
lives -
any more than non halogen lamps with the same filaments.

You're right about the halogen being there to keep the glass clean, but
not about the longer life. A 3400K mogul-base photoflood, like the ones I
used to use in the 1970s, has a lifetime of about 25 hours.

** Really ?

What is that supposed to prove ? ?

Is that not a 120V quartz-halogen lamp ???

A 24V, 150W, 3300K QI ( 35mm slide) projector lamp has a rated life of 50
hours.

Such lamps have been in use common since the late 1960s.

No, it's apples-to-apples, as I said. The mogul-base floods were just
like really big, ordinary incandescents. Thin glass, low pressure argon
fill. No quartz, no halogen. The envelopes got black really fast, even
though they were much larger than normal medium-base bulbs.



The high gas pressure inside quartz-halogen bulbs is what requires the
very thick quartz envelopes. High pressure slows down the diffusion of
tungsten vapour away from the hot spots, so that metal is selectively
redeposited near where it evaporated.


** ROTFL.

It is NOT in the SAME places and huge gaps open up.

See the pics on Wiki.


It isn't a perfect solution, because otherwise the bulb would never
fail. So what? The numbers are as I posted--about a 20x lifetime increase.

You're out of your depth on this one, Phil.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058

hobbs at electrooptical dot net
http://electrooptical.net

On Sat, 15 Dec 2012 03:29:31 -0800, "William Sommerwerck"
wrote:

There are many situations where halogen lamps are dimmed successfully.

** Not many - ALL !!

For various values of "successfully", perhaps.

I won't gainsay any of your other remarks. But I've seen this.

Other remarks? Where? You've seen them ALL? I'm impressed.

"Phil Hobbs"
Phil Allison wrote:


** The simple fact is that halogen lamps do NOT have especially long
lives -
any more than non halogen lamps with the same filaments.

You're right about the halogen being there to keep the glass clean, but
not about the longer life. A 3400K mogul-base photoflood, like the ones
I
used to use in the 1970s, has a lifetime of about 25 hours.

** Really ?

What is that supposed to prove ? ?

Is that not a 120V quartz-halogen lamp ???

A 24V, 150W, 3300K QI ( 35mm slide) projector lamp has a rated life of
50
hours.

Such lamps have been in use common since the late 1960s.

No, it's apples-to-apples, as I said.


** Blatant lie.

The mogul-base floods were just like really big, ordinary incandescents.


** My properly detailed example proves you wrong.

Dickhead.


The high gas pressure inside quartz-halogen bulbs is what requires the
very thick quartz envelopes. High pressure slows down the diffusion of
tungsten vapour away from the hot spots, so that metal is selectively
redeposited near where it evaporated.


** ROTFL.

It is NOT in the SAME places and huge gaps open up.

See the pics on Wiki.


It isn't a perfect solution, because otherwise the bulb would never fail.
So what? The numbers are as I posted--about a 20x lifetime increase.


** Shame the QI lamp example I posted PROVES you wrong.


You're out of your depth on this one,


** Fraid you have already DROWNED !!

What a pathetic fake and damn liar.

**** off.


..... Phil

** Drop dead, you pig ignorant TROLL

On Sun, 16 Dec 2012 07:42:26 +1100, "Phil Allison"
wrote:





** Drop dead, you pig ignorant TROLL


Lies will get you nowhere, Phyllis.