On 2012-10-03, Geoffrey S. Mendelson wrote:


My choices are to once a week clean out a jam, and clean the feed roller;
print something everyday (a waste of paper)

load the paper tray with scrap paper, use the bypass when you want to
print something for real.

another option is to make a document with no ink and print that each day
at the end of the week collect the blank pages from the output tray
and put them back in the input tray.

--
š‚šƒ 100% natural

--- news://freenews.netfront.net/ - complaints: ---

On 03/10/2012 00:49, William Sommerwerck wrote:
"David Woolley" wrote in message
...
William Sommerwerck wrote:

My new computer has a solid-state "hard disk", and you
wouldn't believe how fast it boots up, or how fast programs
start to run.

These, if flash memory, do have a definite wear out mechanism,
although they do try to avoid writing to the same spot, even if the
software does, to mitigate this.

Correct. SSDs are an exception. They contain "leveling" software that makes
sure the disk is written to evenly. The Crucial disk I use is spec'd at
about 40TB of total writes.

For most usage scenarios the theoretical lifetimes of modern SSDs are
longer than HDDs.

On 10/03/2012 09:41 PM, Jeff Liebermann wrote:
On Wed, 03 Oct 2012 10:32:57 -0400, Phil Hobbs
wrote:

I don't know of any data that supports this common idea, but I'd be
interested in reading about it if anybody's actually done the experiment
carefully.

It's an accelerated life test. The deration curve of the incandescent
light bulb is well known and assumed to be
(Vapplied/Vdesign)^-12 to ^-16 * Life at design voltage
http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3544HPX_Catalog_2_11_09.pdf
See Fig 5 on Pg 5 for the graph. Nobody wants to wait 1000 hours for
a bulb to blow. So, they increase the applied voltage, which
dramatically decreases the lifetime down to reasonable test times.
Using a rack of bulbs, they obtain an average (or median) lifetime at
the higher voltage. Then, they work backwards on the curve to
estimate what it would be at the design voltage.

You can't run an accelerated life test when the exponent isn't known
more accurately than 12 to 16.


When I was specifying lamps for a direction finder for the USCG, I had
to deal with minimum lifetime specs. I asked the vendor (Dialight)
how they tested their T-1 3/4 bulbs and was told that they did an
accelerated lifetime test on a few bulbs from each lot to insure
adequate lifetime along with the usual sampled 1.5% AQL failure test.

Electromigration is a smaller effect in an AC bulb, since
the leading order effect cancels.

Yep. As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.


I suspect that the notion that cycling is hard on bulbs comes from the
way that the bulb often fails at turn-on, when the thinnest hot spot
vapourizes before the rest of the filament has a chance to come up to
temperature and reduce the inrush current.

Yep. See my comments on the relatively high failure rate on the
40watt theater marquee lamps due to cycling. The same lamps in the
lobby and foyer were not cycled and seemed to last forever.

I was actually disagreeing with you. There are lots of possible reasons
for the marquee lights failing prematurely. I'm not a tungsten expert
myself, so I'd be very interested in seeing actual data that shows a
dramatic shortening of life due to cycling. I'm not saying it's
impossible, just that I haven't seen any such data.


The tungsten in the lamp is run within a few hundred kelvins of its
melting point, so it's always in the fully annealed state, which ought
to mean that there are no metal fatigue mechanisms operating, just
material migration due to sublimation.

Yep, but different failure mode. When the extremely thin layer of
tungsten plating evaporates, the light becomes dimmer. Below some
brightness level, it is considered to have failed. However, most such
tungsten coated filaments fail due to corrosion of the base steel
alloy wire which is exposed to the internal gases inside the bulb
after the tungsten evaporates. The gases (mostly nitrogen and some
argon) are inert, but there's a little water vapor outgassing from
heating the glass envelope, which eventually corrodes the filament.
Other failure modes are hot spots and notches caused by manufacturing
variations and tungsten evaporation.


The filament isn't tungsten-plated, it's pure tungsten or a low alloy.
The brightness drop comes from tungsten condensing on the envelope.

And the connecting wire isn't plain steel, it's generally Dumet,
http://www.jlcelectromet.com/dumetwire.htm

which is a 42% Ni steel with OFHC copper or nickel plating.

You're making a lot of that up. I'd still like to see
carefully-collected data.

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 Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs
wrote:

On 10/03/2012 09:41 PM, Jeff Liebermann wrote:
On Wed, 03 Oct 2012 10:32:57 -0400, Phil Hobbs
wrote:

I don't know of any data that supports this common idea, but I'd be
interested in reading about it if anybody's actually done the experiment
carefully.

It's an accelerated life test. The deration curve of the incandescent
light bulb is well known and assumed to be
(Vapplied/Vdesign)^-12 to ^-16 * Life at design voltage
http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3544HPX_Catalog_2_11_09.pdf
See Fig 5 on Pg 5 for the graph. Nobody wants to wait 1000 hours for
a bulb to blow. So, they increase the applied voltage, which
dramatically decreases the lifetime down to reasonable test times.
Using a rack of bulbs, they obtain an average (or median) lifetime at
the higher voltage. Then, they work backwards on the curve to
estimate what it would be at the design voltage.

You can't run an accelerated life test when the exponent isn't known
more accurately than 12 to 16.

True, but I believe that's the range expected from different types of
light bulbs (nitrogen filled, halogen, vaccuum), and not the range
expected for a given device. I suspect that more accurate exponent
value could be empirically determined for a given device, and later
used only for that device.

Yep. As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

http://en.wikipedia.org/wiki/Incandescent_light_bulb#Reducing_filament_evaporat ion
One of the problems of the standard electric light bulb is
evaporation of the filament. Small variations in resistivity
along the filament cause "hot spots" to form at points of
higher resistivity; a variation of diameter of only 1% will
cause a 25% reduction in service life. The hot spots evaporate
faster than the rest of the filament, increasing resistance
at that point a positive feedback that ends in the familiar
tiny gap in an otherwise healthy-looking filament.

Note the photo of the filament with a break in the middle. When I was
quite young, I would break burnt out AC light bulbs to see what was
inside. If the filament was intact, the break was always somewhere
near the middle. If a piece broke off, one end of the broken piece
was usually near the middle. In later years, I would look at the
remains of DC panel lights (usually type 47 for old Motorola radios)
and noted that the breaks were always near the supporting terminals,
probably due to metal migration.

I suspect that the notion that cycling is hard on bulbs comes from the
way that the bulb often fails at turn-on, when the thinnest hot spot
vapourizes before the rest of the filament has a chance to come up to
temperature and reduce the inrush current.

Yep. See my comments on the relatively high failure rate on the
40watt theater marquee lamps due to cycling. The same lamps in the
lobby and foyer were not cycled and seemed to last forever.

I was actually disagreeing with you. There are lots of possible reasons
for the marquee lights failing prematurely. I'm not a tungsten expert
myself, so I'd be very interested in seeing actual data that shows a
dramatic shortening of life due to cycling. I'm not saying it's
impossible, just that I haven't seen any such data.

So much for my anecdotal data. My theater marquee experience was in
about 1966. The theater actually did keep records so that they could
stock enough replacement bulbs, but I don't have copies of any of
that.

I tried Googling for similar repetative on-off tests and didn't find
anything. If I have time, I'll try again. I must admit that the lack
of test data does look suspicious. Perhaps sending the idea to
Mythbusters and have them runs a test?

The filament isn't tungsten-plated, it's pure tungsten or a low alloy.
The brightness drop comes from tungsten condensing on the envelope.

Oops. I thought it was plated.

And the connecting wire isn't plain steel, it's generally Dumet,
http://www.jlcelectromet.com/dumetwire.htm

which is a 42% Ni steel with OFHC copper or nickel plating.

You're making a lot of that up. I'd still like to see
carefully-collected data.

No, not fabricated. It's my reliance on my memory in an area that I'm
not familiar with. I tried Googling for the wire used, couldn't find
much, and made a bad guess. The plating came from somehow getting
thorium coated tungsten wire used in vacuum tubes mixed up with light
bulbs. Sorry for the errors and muddle.

Cheers
Phil Hobbs

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Wed, 3 Oct 2012 10:34:04 +0000 (UTC), "Geoffrey S. Mendelson"
wrote:

Tom Biasi wrote:
Not so. With mechanical devices, regular moderate use provides a longer
useful lifetime than using the device only rarely.


I don't agree but will say no more.

Laser printers. I have given away for parts several laser printers because
they sat unused 99% of the time, and started to jam when I printed the
one or two pages a month I needed them for.

I've seen flat spots on laser printers. However, just running a few
pages through the printer usually returns them to normal. If not, use
some rubber roller restorer to soften the rubber.
http://www.fixyourownprinter.com/specials/misc/all/S03

In my experience, many printer jams are caused by paper slippage on
the rollers. Usually, it's the white paper dust that causes slippage,
but it can easily be household dust accumulated over the time the
printer was idle. Maybe hitting the printer with a compressed air
blast before operating might help.

Another slippage problem is when the rubber surface becomes glazed or
polished. The rubber roller restorer will take the surface gloss off
the rollers, and improve the traction, but if there's any rubber wear,
the roller(s) should be replaced.

Not only did the rubber wheels dry out and lose their ability to grab paper,
they flatten where they are pressed against something.

I have a perfectly good Samsung laser printer in that condition now.

Ugh. I don't have much nice to say about Samsung printers. They're
cheap, function adequately, use overpriced toner carts, and don't last
very long. I've never really done an autopsy to isolate a culprit.
The usual end of life symptoms are either paper jams or flimsy broken
plastic parts.

My choices are to once a week clean out a jam, and clean the feed roller;
print something everyday (a waste of paper); spend $15 for a new roller
(including postage) and an hour to install it; or wait for a sale
(every 2-3 months) and buy a newer faster, higher resolution model with a
2,000 page toner cartridge included for less than the cost of a full load toner.

Chuckle. Yeah, that's about it. Next purchase, I suggest HP LaserJet
printers. They have their own collection of problems, but parts and
refills are commonly available and cheap. The printer cannibals sell
used parts and assemblies fairly cheap on eBay. Also, expertise is
more easily found:
http://www.fixyourownprinter.com
My favorite printer of the week is the HP 2300DN or DTN at between $90
to $220 used depending on condition and options. Favorite feature is
double sided (duplex) printing.

Geoff.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Wed, 03 Oct 2012 19:42:21 -0400, "
wrote:

My 39YO HP45 still works but the power switch is too flaky to be usable.

I collect old HP LED type calculators. The HP 45 is well worth fixing
and using.

The switches tend to fail due to dirt accumulation and/or wearing a
grove into the PCB contact area from overuse. I've repaired both
problems.
http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv018.cgi?read=131014
This is the dirt problem:
http://i45.photobucket.com/albums/f96/geoff_q/gunk.jpg
I couldn't find a photo of a grove worn in the contacts. I've been
quite successful with just cleaning the switch area. I've also
repaired missing gold problems with gold leaf. It was difficult,
required a microscope, a steady hand, no air movement, and
considerable patience.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Oct 4, 12:43*pm, Jeff Liebermann wrote:
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs





wrote:
On 10/03/2012 09:41 PM, Jeff Liebermann wrote:
On Wed, 03 Oct 2012 10:32:57 -0400, Phil Hobbs
*wrote:

I don't know of any data that supports this common idea, but I'd be
interested in reading about it if anybody's actually done the experiment
carefully.

It's an accelerated life test. *The deration curve of the incandescent
light bulb is well known and assumed to be
* *(Vapplied/Vdesign)^-12 to ^-16 * Life at design voltage
http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3....
See Fig 5 on Pg 5 for the graph. *Nobody wants to wait 1000 hours for
a bulb to blow. *So, they increase the applied voltage, which
dramatically decreases the lifetime down to reasonable test times.
Using a rack of bulbs, they obtain an average (or median) lifetime at
the higher voltage. *Then, they work backwards on the curve to
estimate what it would be at the design voltage.

You can't run an accelerated life test when the exponent isn't known
more accurately than 12 to 16.

True, but I believe that's the range expected from different types of
light bulbs (nitrogen filled, halogen, vaccuum), and not the range
expected for a given device. *I suspect that more accurate exponent
value could be empirically determined for a given device, and later
used only for that device.

Yep. *As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. *The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

http://en.wikipedia.org/wiki/Incandescent_light_bulb#Reducing_filamen...
* *One of the problems of the standard electric light bulb is
* *evaporation of the filament. Small variations in resistivity
* *along the filament cause "hot spots" to form at points of
* *higher resistivity; a variation of diameter of only 1% will
* *cause a 25% reduction in service life. The hot spots evaporate
* *faster than the rest of the filament, increasing resistance
* *at that point a positive feedback that ends in the familiar
* *tiny gap in an otherwise healthy-looking filament.

Note the photo of the filament with a break in the middle. *When I was
quite young, I would break burnt out AC light bulbs to see what was
inside. *If the filament was intact, the break was always somewhere
near the middle. *If a piece broke off, one end of the broken piece
was usually near the middle. *In later years, I would look at the
remains of DC panel lights (usually type 47 for old Motorola radios)
and noted that the breaks were always near the supporting terminals,
probably due to metal migration.

I suspect that the notion that cycling is hard on bulbs comes from the
way that the bulb often fails at turn-on, when the thinnest hot spot
vapourizes before the rest of the filament has a chance to come up to
temperature and reduce the inrush current.

Yep. *See my comments on the relatively high failure rate on the
40watt theater marquee lamps due to cycling. *The same lamps in the
lobby and foyer were not cycled and seemed to last forever.

I was actually disagreeing with you. *There are lots of possible reasons
for the marquee lights failing prematurely. *I'm not a tungsten expert
myself, so I'd be very interested in seeing actual data that shows a
dramatic shortening of life due to cycling. *I'm not saying it's
impossible, just that I haven't seen any such data.

So much for my anecdotal data. *My theater marquee experience was in
about 1966. *The theater actually did keep records so that they could
stock enough replacement bulbs, but I don't have copies of any of
that.

I tried Googling for similar repetative on-off tests and didn't find
anything. *If I have time, I'll try again. *I must admit that the lack
of test data does look suspicious. *Perhaps sending the idea to
Mythbusters and have them runs a test?

The filament isn't tungsten-plated, it's pure tungsten or a low alloy.
The brightness drop comes from tungsten condensing on the envelope.

Oops. *I thought it was plated.

And the connecting wire isn't plain steel, it's generally Dumet,
http://www.jlcelectromet.com/dumetwire.htm

which is a 42% Ni steel with OFHC copper or nickel plating.

You're making a lot of that up. *I'd still like to see
carefully-collected data.

No, not fabricated. *It's my reliance on my memory in an area that I'm
not familiar with. *I tried Googling for the wire used, couldn't find
much, and made a bad guess. *The plating came from somehow getting
thorium coated tungsten wire used in vacuum tubes mixed up with light
bulbs. *Sorry for the errors and muddle.

Cheers
Phil Hobbs

--
Jeff Liebermann * *
150 Felker St #D * *http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann * * AE6KS * *831-336-2558- Hide quoted text -

- Show quoted text -

Hi Jeff, Phil. First I know nothing about incandescent bulbs.
But how about this as a model of why turning bulbs on and off might
cause them to fail sooner.

1.) I think we all observe that bulbs tend to blow when you turn them
on.
(unless you knock the lamp over or something.)

2.) I assume that the failure is mostly due to the thinner ‘hot spots’
on the filament. Thinner regions heat up faster (higher resistance
with equal current).

3.) Now even if the thinner region doesn’t blow, it still gets hotter
and loses a bit more tungsten than the rest of the filament. (For
that small amount of time that it’s turning on.) But still this means
that turning on the bulb causes the thin region to become a bit
thinner.

And that’s it. Repeated on and off means that the thin region has a
higher average temperature than the thick part of the filament. It
evaporates faster and fails sooner.

George H.

On 10/04/2012 02:57 PM, George Herold wrote:
On Oct 4, 12:43 pm, Jeff wrote:
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs





wrote:
On 10/03/2012 09:41 PM, Jeff Liebermann wrote:
On Wed, 03 Oct 2012 10:32:57 -0400, Phil Hobbs
wrote:

I don't know of any data that supports this common idea, but I'd be
interested in reading about it if anybody's actually done the experiment
carefully.

It's an accelerated life test. The deration curve of the incandescent
light bulb is well known and assumed to be
(Vapplied/Vdesign)^-12 to ^-16 * Life at design voltage
http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3...
See Fig 5 on Pg 5 for the graph. Nobody wants to wait 1000 hours for
a bulb to blow. So, they increase the applied voltage, which
dramatically decreases the lifetime down to reasonable test times.
Using a rack of bulbs, they obtain an average (or median) lifetime at
the higher voltage. Then, they work backwards on the curve to
estimate what it would be at the design voltage.

You can't run an accelerated life test when the exponent isn't known
more accurately than 12 to 16.

True, but I believe that's the range expected from different types of
light bulbs (nitrogen filled, halogen, vaccuum), and not the range
expected for a given device. I suspect that more accurate exponent
value could be empirically determined for a given device, and later
used only for that device.

Yep. As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

http://en.wikipedia.org/wiki/Incandescent_light_bulb#Reducing_filamen...
One of the problems of the standard electric light bulb is
evaporation of the filament. Small variations in resistivity
along the filament cause "hot spots" to form at points of
higher resistivity; a variation of diameter of only 1% will
cause a 25% reduction in service life. The hot spots evaporate
faster than the rest of the filament, increasing resistance
at that point a positive feedback that ends in the familiar
tiny gap in an otherwise healthy-looking filament.

Note the photo of the filament with a break in the middle. When I was
quite young, I would break burnt out AC light bulbs to see what was
inside. If the filament was intact, the break was always somewhere
near the middle. If a piece broke off, one end of the broken piece
was usually near the middle. In later years, I would look at the
remains of DC panel lights (usually type 47 for old Motorola radios)
and noted that the breaks were always near the supporting terminals,
probably due to metal migration.

I suspect that the notion that cycling is hard on bulbs comes from the
way that the bulb often fails at turn-on, when the thinnest hot spot
vapourizes before the rest of the filament has a chance to come up to
temperature and reduce the inrush current.

Yep. See my comments on the relatively high failure rate on the
40watt theater marquee lamps due to cycling. The same lamps in the
lobby and foyer were not cycled and seemed to last forever.

I was actually disagreeing with you. There are lots of possible reasons
for the marquee lights failing prematurely. I'm not a tungsten expert
myself, so I'd be very interested in seeing actual data that shows a
dramatic shortening of life due to cycling. I'm not saying it's
impossible, just that I haven't seen any such data.

So much for my anecdotal data. My theater marquee experience was in
about 1966. The theater actually did keep records so that they could
stock enough replacement bulbs, but I don't have copies of any of
that.

I tried Googling for similar repetative on-off tests and didn't find
anything. If I have time, I'll try again. I must admit that the lack
of test data does look suspicious. Perhaps sending the idea to
Mythbusters and have them runs a test?

The filament isn't tungsten-plated, it's pure tungsten or a low alloy.
The brightness drop comes from tungsten condensing on the envelope.

Oops. I thought it was plated.

And the connecting wire isn't plain steel, it's generally Dumet,
http://www.jlcelectromet.com/dumetwire.htm

which is a 42% Ni steel with OFHC copper or nickel plating.

You're making a lot of that up. I'd still like to see
carefully-collected data.

No, not fabricated. It's my reliance on my memory in an area that I'm
not familiar with. I tried Googling for the wire used, couldn't find
much, and made a bad guess. The plating came from somehow getting
thorium coated tungsten wire used in vacuum tubes mixed up with light
bulbs. Sorry for the errors and muddle.

Cheers
Phil Hobbs

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558- Hide quoted text -

- Show quoted text -

Hi Jeff, Phil. First I know nothing about incandescent bulbs.
But how about this as a model of why turning bulbs on and off might
cause them to fail sooner.

1.) I think we all observe that bulbs tend to blow when you turn them
on.
(unless you knock the lamp over or something.)

2.) I assume that the failure is mostly due to the thinner ‘hot spots’
on the filament. Thinner regions heat up faster (higher resistance
with equal current).

3.) Now even if the thinner region doesn’t blow, it still gets hotter
and loses a bit more tungsten than the rest of the filament. (For
that small amount of time that it’s turning on.) But still this means
that turning on the bulb causes the thin region to become a bit
thinner.

And that’s it. Repeated on and off means that the thin region has a
higher average temperature than the thick part of the filament. It
evaporates faster and fails sooner.

George H.

If the effect is real, that sounds like a good candidate for a
mechanism. Certainly you'd expect that to be important right near the
end of the bulb's life, so maybe it's important throughout.

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 Thu, 4 Oct 2012 11:57:21 -0700 (PDT), George Herold
wrote:

Hi Jeff, Phil. First I know nothing about incandescent bulbs.

I'm still learning (mostly from my mistakes).

I blundered across this video on tungsten filaments.
http://www.youtube.com/watch?v=DIGqBb3iZPo 3:38
While it doesn't touch any of the issues previously mentioned, it does
include some interesting info on how the filament is made and its
structure.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 10/3/2012 2:01 AM, MikeS wrote:

Using anything shortens it's working life.

Seems to go against the whole ethos of exercising. Never get out of bed and
live forever ...


If you were an android that may be true.

On Oct 4, 4:28*pm, Phil Hobbs
wrote:
On 10/04/2012 02:57 PM, George Herold wrote:





On Oct 4, 12:43 pm, Jeff *wrote:
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs

*wrote:
On 10/03/2012 09:41 PM, Jeff Liebermann wrote:
On Wed, 03 Oct 2012 10:32:57 -0400, Phil Hobbs
* *wrote:

I don't know of any data that supports this common idea, but I'd be
interested in reading about it if anybody's actually done the experiment
carefully.

It's an accelerated life test. *The deration curve of the incandescent
light bulb is well known and assumed to be
* * (Vapplied/Vdesign)^-12 to ^-16 * Life at design voltage
http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3...
See Fig 5 on Pg 5 for the graph. *Nobody wants to wait 1000 hours for
a bulb to blow. *So, they increase the applied voltage, which
dramatically decreases the lifetime down to reasonable test times.
Using a rack of bulbs, they obtain an average (or median) lifetime at
the higher voltage. *Then, they work backwards on the curve to
estimate what it would be at the design voltage.

You can't run an accelerated life test when the exponent isn't known
more accurately than 12 to 16.

True, but I believe that's the range expected from different types of
light bulbs (nitrogen filled, halogen, vaccuum), and not the range
expected for a given device. *I suspect that more accurate exponent
value could be empirically determined for a given device, and later
used only for that device.

Yep. *As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. *The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

http://en.wikipedia.org/wiki/Incandescent_light_bulb#Reducing_filamen....
* * One of the problems of the standard electric light bulb is
* * evaporation of the filament. Small variations in resistivity
* * along the filament cause "hot spots" to form at points of
* * higher resistivity; a variation of diameter of only 1% will
* * cause a 25% reduction in service life. The hot spots evaporate
* * faster than the rest of the filament, increasing resistance
* * at that point a positive feedback that ends in the familiar
* * tiny gap in an otherwise healthy-looking filament.

Note the photo of the filament with a break in the middle. *When I was
quite young, I would break burnt out AC light bulbs to see what was
inside. *If the filament was intact, the break was always somewhere
near the middle. *If a piece broke off, one end of the broken piece
was usually near the middle. *In later years, I would look at the
remains of DC panel lights (usually type 47 for old Motorola radios)
and noted that the breaks were always near the supporting terminals,
probably due to metal migration.

I suspect that the notion that cycling is hard on bulbs comes from the
way that the bulb often fails at turn-on, when the thinnest hot spot
vapourizes before the rest of the filament has a chance to come up to
temperature and reduce the inrush current.

Yep. *See my comments on the relatively high failure rate on the
40watt theater marquee lamps due to cycling. *The same lamps in the
lobby and foyer were not cycled and seemed to last forever.

I was actually disagreeing with you. *There are lots of possible reasons
for the marquee lights failing prematurely. *I'm not a tungsten expert
myself, so I'd be very interested in seeing actual data that shows a
dramatic shortening of life due to cycling. *I'm not saying it's
impossible, just that I haven't seen any such data.

So much for my anecdotal data. *My theater marquee experience was in
about 1966. *The theater actually did keep records so that they could
stock enough replacement bulbs, but I don't have copies of any of
that.

I tried Googling for similar repetative on-off tests and didn't find
anything. *If I have time, I'll try again. *I must admit that the lack
of test data does look suspicious. *Perhaps sending the idea to
Mythbusters and have them runs a test?

The filament isn't tungsten-plated, it's pure tungsten or a low alloy..
The brightness drop comes from tungsten condensing on the envelope.

Oops. *I thought it was plated.

And the connecting wire isn't plain steel, it's generally Dumet,
http://www.jlcelectromet.com/dumetwire.htm

which is a 42% Ni steel with OFHC copper or nickel plating.

You're making a lot of that up. *I'd still like to see
carefully-collected data.

No, not fabricated. *It's my reliance on my memory in an area that I'm
not familiar with. *I tried Googling for the wire used, couldn't find
much, and made a bad guess. *The plating came from somehow getting
thorium coated tungsten wire used in vacuum tubes mixed up with light
bulbs. *Sorry for the errors and muddle.

Cheers
Phil Hobbs

--
Jeff Liebermann * *
150 Felker St #D * *http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann * * AE6KS * *831-336-2558- Hide quoted text -

- Show quoted text -

Hi Jeff, Phil. * First I know nothing about incandescent bulbs.
But how about this as a model of why turning bulbs on and off might
cause them to fail sooner.

1.) I think we all observe that bulbs tend to blow when you turn them
on.
(unless you knock the lamp over or something.)

2.) I assume that the failure is mostly due to the thinner �hot spots�
on the filament. * Thinner regions heat up faster (higher resistance
with equal current).

3.) Now even if the thinner region doesn�t blow, it still gets hotter
and loses a bit more tungsten than the rest of the filament. * (For
that small amount of time that it�s turning on.) *But still this means
that turning on the bulb causes the thin region to become a bit
thinner.

And that�s it. *Repeated on and off means that the thin region has a
higher average temperature than the thick part of the filament. *It
evaporates faster and fails sooner.

George H.

If the effect is real, that sounds like a good candidate for a
mechanism. * Certainly you'd expect that to be important right near the
end of the bulb's life, so maybe it's important throughout.

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 nethttp://electrooptical.net- Hide quoted text -

- Show quoted text -

Yeah, I was thinking about this while splitting/stacking wood
tonight.
If the time to fail goes as some big power of the voltage
(temperature),
then during turn on, small diameter variations (or defects)
get amplfied.

A 'long life' 40 Watt bulb would fail almost as fast as a 100 W'er.

(Of course I've got my 'lifetime supply' of 100W bulbs, and didn't
budget any for research.)

George H.

On Oct 4, 5:05*pm, Jeff Liebermann wrote:
On Thu, 4 Oct 2012 11:57:21 -0700 (PDT), George Herold

wrote:
Hi Jeff, Phil. * First I know nothing about incandescent bulbs.

I'm still learning (mostly from my mistakes).

It's definitely my mistakes that have taught me the most.

(my latest f-up had to do with short ultrasonic pulses,
and 1/4 wavelength anti-reflection wave-plates...)

I've no problem with your marquee story. Sometimes folk-tales about
rocks falling from the sky are correct.
The data point I offer to Phil is that bulbs fail when you turn them
on. I see no reason why that can't be 'played backwards'. There most
be some GE, Philips, (other) report that documents turn on failure.

George H.

I blundered across this video on tungsten filaments.
http://www.youtube.com/watch?v=DIGqBb3iZPo *3:38
While it doesn't touch any of the issues previously mentioned, it does
include some interesting info on how the filament is made and its
structure.

--
Jeff Liebermann * *
150 Felker St #D * *http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann * * AE6KS * *831-336-2558

On Tue, 2 Oct 2012 22:21:26 +0100, "jim stone"
wrote:

Not being able to find a small internet radio to buy we liked, we got mobile
phone with which we link with wi-fi to a modem router, and use it as an
internet radio.

Keeping the phoned plugged into its charger all the time, we are using it to
play *all-day* background classical music through an amplifier and speakers.

Several of my customers do exactly the same thing. Some play stored
MP3/AAC music, while others stream from Pandora or Slacker. Most use
an iPhone 3G, iPod Touch, or Droid A855 for the wi-fi connectivity.
All have the phone plugged into a charger. No fatalities.

Since the phone has no 'moving parts' unlike a computer, we are wondering if
this continuous playing all day of the phone is going to shorten its working
life ?

It won't hurt the phone in any way. However, the internal battery is
another story. For Li-Ion, battery life is shortened when the battery
is hot, and when it's left at full charge all the time. For details,
see:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
Most Li-ions are charged to 4.20V/cell and every reduction
of 0.10V/cell is said to double cycle life.
This is not much of a problem for easily replaceable inexpensive
batteries, such as in the Droid A855, but might be an issue with the
designed obsolescent iPhone series, where brain surgery is required to
replace the battery. Apple has therefore wisely elected to charge
their Li-Ion batteries to 4.1v or what I estimate to be 95% of full
capacity. This greatly extends the battery life and will delay when
you start cursing Apple products to about 3 years.
http://stephenwmoore.wordpress.com/2009/07/21/iphone-battery-life/

Someone mentioned having a phone with a dead wi-fi. I have two Apple
3G iPhones, both with intermittent wi-fi sections. If I turn the
power off on the iPhone for a day, the iPhones will have a working
wi-fi section for about 30 minutes. I also have a third working
iPhone 3G, where the wi-fi has never failed. I've been inside trying
to repair them, and failed.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

In article de99517e-e5e1-4f9d-91e0-
, George Herold wrote:
And that’s it. Repeated on and off means that the thin region has a
higher average temperature than the thick part of the filament. It
evaporates faster and fails sooner.

Won't a thin region of a lamp filament have a higher temperature than
the rest of it all the time, not just when the lamp is turning on?

Rod.
--

On Oct 5, 6:20*am, Roderick Stewart
wrote:
In article de99517e-e5e1-4f9d-91e0-

, George Herold wrote:
And that s it. *Repeated on and off means that the thin region has a
higher average temperature than the thick part of the filament. *It
evaporates faster and fails sooner.

Won't a thin region of a lamp filament have a higher temperature than
the rest of it all the time, not just when the lamp is turning on?

Rod.
--

Hmm, sure, maybe... I really have no idea. But I can't remember ever
seeing a bulb fail after being on for a while. (I'm sure it must
happen.) They almost always go when you turn them on, from which I
conclude that the turn on is more 'stressful'.

Say does Don Klipstein still lurk here? He may have some info on turn-
on failure.

http://donklipstein.com/

George H.

On Fri, 5 Oct 2012 07:43:56 -0700 (PDT), George Herold
wrote:

Say does Don Klipstein still lurk here? He may have some info on turn-
on failure.
http://donklipstein.com/
George H.

Thanks. He has a section on why and how bulbs burn out at:
http://donklipstein.com/bulb1.html#how

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 10/05/2012 06:20 AM, Roderick Stewart wrote:
In articlede99517e-e5e1-4f9d-91e0-
, George Herold wrote:
And that’s it. Repeated on and off means that the thin region has a
higher average temperature than the thick part of the filament. It
evaporates faster and fails sooner.

Won't a thin region of a lamp filament have a higher temperature than
the rest of it all the time, not just when the lamp is turning on?

Rod.
--


Thin spots will evaporate faster at all times, sure. The main question
as to whether George's mechanism explains the alleged effect is whether,
in a newish bulb, the inrush makes the hotspots exceed 2800K or whatever
the normal filament temperature is, before the the inrush current subsides.

I'd expect that to be more of a threshold effect, because the resistance
of the filament ought to be pretty linear with temperature, whereas the
evaporation essentially turns on at around 2500K, so the hot spots would
have to be pretty thin already for it to do much.

But as I say, I'm far from being a tungsten bulb expert myself.

Cheers

Phil Hobbs

On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs
wrote:

Yep. As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

Oscillating filament light bulb:
http://www.youtube.com/watch?v=t_DwwNVA-7Q
Whether the earths magnetic field is strong enough to induce such
oscillations is questionable.

While digging for the apparently mythical lifetime test data on
incandescent light bulbs, I've found numerous theories on why
filaments fail. Tungsten evaporation, causing hot spots, is the most
common. One suggested that thermal cycling hardens the tungsten and
makes it brittle. Another suggested that the inrush current causes a
mechanical shock if it hits at the 60Hz peak, instead of at the zero
crossing. Yet another speculates that the temperature differential
between the hot filament, and the relatively cold mounting structure
may cause cracking.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

George Herold wrote:

Hmm, sure, maybe... I really have no idea. But I can't remember ever
seeing a bulb fail after being on for a while.


It happens quite often in TV studios.

On Oct 5, 2:51*pm, Jeff Liebermann wrote:
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs

wrote:
Yep. *As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. *The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

Oscillating filament light bulb:
http://www.youtube.com/watch?v=t_DwwNVA-7Q
Whether the earths magnetic field is strong enough to induce such
oscillations is questionable.

While digging for the apparently mythical lifetime test data on
incandescent light bulbs, I've found numerous theories on why
filaments fail.

Grin, the internet as a 'fire hose' of information. I went searching
for something that contained "Philips tech. rev." and found a
reference to the following article,

H. Horster, E. Kauer and W. Lechner — The Burn-out Mechanism of
Incandescent Lamps Philips Technical Review 32,155-164, 1971.

It was referenced in "Illuminating Engineering - Page 32 - Google
Books"

But nothing about turn on failure... sigh.

Here is a patent by some of the same guys at Philips... lots of stuff
about the filament getting hottest in the middle.

http://www.freepatentsonline.com/3868159.html
(Actually a decently written patent.)

George H.



Tungsten evaporation, causing hot spots, is the most
common. *One suggested that thermal cycling hardens the tungsten and
makes it brittle. *Another suggested that the inrush current causes a
mechanical shock if it hits at the 60Hz peak, instead of at the zero
crossing. *Yet another speculates that the temperature differential
between the hot filament, and the relatively cold mounting structure
may cause cracking.

--
Jeff Liebermann * *
150 Felker St #D * *http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann * * AE6KS * *831-336-2558

G

Phil Hobbs wrote:

I've never had a package stolen, as far as I can recall.


Me, either. It's probably that their postal system won't come to
reasonable terms with the US postal system.

Jeff Liebermann wrote:

On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs
wrote:

Yep. As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

Oscillating filament light bulb:
http://www.youtube.com/watch?v=t_DwwNVA-7Q
Whether the earths magnetic field is strong enough to induce such
oscillations is questionable.

While digging for the apparently mythical lifetime test data on
incandescent light bulbs, I've found numerous theories on why
filaments fail. Tungsten evaporation, causing hot spots, is the most
common. One suggested that thermal cycling hardens the tungsten and
makes it brittle. Another suggested that the inrush current causes a
mechanical shock if it hits at the 60Hz peak, instead of at the zero
crossing. Yet another speculates that the temperature differential
between the hot filament, and the relatively cold mounting structure
may cause cracking.

--

All of those except the hot spot mechanism assume that the tungsten
work-hardens in the bulb and then fails from fatigue. However, that
isn't the case, because the annealing temperature of tungsten is about
1300 C, so the tungsten in a light bulb filament is always fully
annealed.

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
845-480-2058

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

George Herold wrote:

On Oct 5, 2:51 pm, Jeff Liebermann wrote:
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs

wrote:
Yep. As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

Oscillating filament light bulb:
http://www.youtube.com/watch?v=t_DwwNVA-7Q
Whether the earths magnetic field is strong enough to induce such
oscillations is questionable.

While digging for the apparently mythical lifetime test data on
incandescent light bulbs, I've found numerous theories on why
filaments fail.

Grin, the internet as a 'fire hose' of information. I went searching
for something that contained "Philips tech. rev." and found a
reference to the following article,

H. Horster, E. Kauer and W. Lechner — The Burn-out Mechanism of
Incandescent Lamps Philips Technical Review 32,155-164, 1971.

It was referenced in "Illuminating Engineering - Page 32 - Google
Books"

But nothing about turn on failure... sigh.

Here is a patent by some of the same guys at Philips... lots of stuff
about the filament getting hottest in the middle.

http://www.freepatentsonline.com/3868159.html
(Actually a decently written patent.)

George H.

Tungsten evaporation, causing hot spots, is the most
common. One suggested that thermal cycling hardens the tungsten and
makes it brittle. Another suggested that the inrush current causes a
mechanical shock if it hits at the 60Hz peak, instead of at the zero
crossing. Yet another speculates that the temperature differential
between the hot filament, and the relatively cold mounting structure
may cause cracking.


I can believe that the filament is hottest in the middle. It's
furtherst from the support, so whatever conductive heat sinking there is
will be less, but more than that, it sees the radiative input from the
rest of the filament on both sides instead of just one.

Sort of similar to the case of a long solenoid, whose B field at the
ends is half what it is in the middle.

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
845-480-2058

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

In article ,
Michael A. Terrell wrote:

Phil Hobbs wrote:

I've never had a package stolen, as far as I can recall.


Me, either. It's probably that their postal system won't come to
reasonable terms with the US postal system.

Other countries seem quite happy to use ordinary post to the UK. The US,
not. So explain that.

--
*Never put off until tomorrow what you can avoid altogether *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote:

In article ,
Michael A. Terrell wrote:

Phil Hobbs wrote:

I've never had a package stolen, as far as I can recall.

Me, either. It's probably that their postal system won't come to
reasonable terms with the US postal system.

Other countries seem quite happy to use ordinary post to the UK. The US,
not. So explain that.


Probably the War of 1812.

Coming from Canada, I can tell you that the USPS is very nearly flawless
when compared with Canada Post. Those morons can't find their rear ends
with both hands and a map.

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
845-480-2058

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

On Fri, 05 Oct 2012 19:00:56 -0400, Phil Hobbs
wrote:

George Herold wrote:

On Oct 5, 2:51 pm, Jeff Liebermann wrote:
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs

wrote:
Yep. As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

Oscillating filament light bulb:
http://www.youtube.com/watch?v=t_DwwNVA-7Q
Whether the earths magnetic field is strong enough to induce such
oscillations is questionable.

While digging for the apparently mythical lifetime test data on
incandescent light bulbs, I've found numerous theories on why
filaments fail.

Grin, the internet as a 'fire hose' of information. I went searching
for something that contained "Philips tech. rev." and found a
reference to the following article,

H. Horster, E. Kauer and W. Lechner — The Burn-out Mechanism of
Incandescent Lamps Philips Technical Review 32,155-164, 1971.

It was referenced in "Illuminating Engineering - Page 32 - Google
Books"

But nothing about turn on failure... sigh.

Here is a patent by some of the same guys at Philips... lots of stuff
about the filament getting hottest in the middle.

http://www.freepatentsonline.com/3868159.html
(Actually a decently written patent.)

George H.

Tungsten evaporation, causing hot spots, is the most
common. One suggested that thermal cycling hardens the tungsten and
makes it brittle. Another suggested that the inrush current causes a
mechanical shock if it hits at the 60Hz peak, instead of at the zero
crossing. Yet another speculates that the temperature differential
between the hot filament, and the relatively cold mounting structure
may cause cracking.


I can believe that the filament is hottest in the middle. It's
furtherst from the support, so whatever conductive heat sinking there is
will be less, but more than that, it sees the radiative input from the
rest of the filament on both sides instead of just one.

Aren't the filaments welded to the elements at the ends? It would seem that
this would cause a narrowing. ISTR most filaments broken near the supports,
which would be counter to the hotter-in-the-middle theory.

My theory is that bulbs tend to fail when turned on because of the thermal
shock but only because they were about to fail anyway. Cycling, itself,
doesn't have a huge effect on longevity, certainly not a factor of two.

Sort of similar to the case of a long solenoid, whose B field at the
ends is half what it is in the middle.

Do they only burn out when energized? ;-)

On Sat, 06 Oct 2012 00:11:01 +0100, "Dave Plowman (News)"
wrote:

In article ,
Michael A. Terrell wrote:

Phil Hobbs wrote:

I've never had a package stolen, as far as I can recall.


Me, either. It's probably that their postal system won't come to
reasonable terms with the US postal system.

Nope, not here either.

Other countries seem quite happy to use ordinary post to the UK. The US,
not. So explain that.

Follow the money.

"Dave Plowman (News)" wrote:

In article ,
Michael A. Terrell wrote:

Phil Hobbs wrote:

I've never had a package stolen, as far as I can recall.

Me, either. It's probably that their postal system won't come to
reasonable terms with the US postal system.

Other countries seem quite happy to use ordinary post to the UK. The US,
not. So explain that.


Sigh. Ask 'your' post office why the rates are so damn high. The
rates are agreed on between countries, and the British system is the
only that people constantly complain about. Likely high tarriffs on
imports from the US that are imposed on incoming goods.

In article ,
says...

On 2012-10-02, jim stone wrote:
Not being able to find a small internet radio to buy we liked, we got mobile
phone with which we link with wi-fi to a modem router, and use it as an
internet radio.

Keeping the phoned plugged into its charger all the time, we are using it to
play *all-day* background classical music through an amplifier and speakers.

Since the phone has no 'moving parts' unlike a computer, we are wondering if
this continuous playing all day of the phone is going to shorten its working
life ?

It may be bad for the battery

My favorite apps on my phone:

TuneIn, Pandora, ScannerRadioPro, EchoLink and RepeaterBook.

And that's kind of why I got the extended battery pack for the phone.

On 06/10/2012 00:15, Phil Hobbs wrote:
"Dave Plowman (News)" wrote:

In article ,
Michael A. Terrell wrote:

Phil Hobbs wrote:

I've never had a package stolen, as far as I can recall.

Me, either. It's probably that their postal system won't come to
reasonable terms with the US postal system.

Other countries seem quite happy to use ordinary post to the UK. The US,
not. So explain that.


Probably the War of 1812.

Coming from Canada, I can tell you that the USPS is very nearly flawless
when compared with Canada Post. Those morons can't find their rear ends
with both hands and a map.


The Americans do seem generally to be used to sending a lot by courier
when we would just put in the post. Tending to happen in the UK also
even though the Royal Mail / Parcelforce often give a better service and
of course do not charge extra to send further. There has been a big
campaign in the North of Scotland about companies charging extra for
many postcode areas.

In article ,
Michael A. Terrell wrote:

"Dave Plowman (News)" wrote:

In article ,
Michael A. Terrell wrote:

Phil Hobbs wrote:

I've never had a package stolen, as far as I can recall.

Me, either. It's probably that their postal system won't come to
reasonable terms with the US postal system.

Other countries seem quite happy to use ordinary post to the UK. The US,
not. So explain that.


Sigh. Ask 'your' post office why the rates are so damn high. The
rates are agreed on between countries, and the British system is the
only that people constantly complain about. Likely high tarriffs on
imports from the US that are imposed on incoming goods.

Sigh. Try reading what was said. Most US companies refuse to send anything
to the UK by normal post. They insist on using a courier service. If the
fault was at the UK end, this would apply to all other countries sending
things here. I know logic isn't your strong point - at least compared to
your blind patriotism - but even then...

--
*Don't squat with your spurs on *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
MB wrote:
The Americans do seem generally to be used to sending a lot by courier
when we would just put in the post.

Quite. And I was simply guessing at an explanation. Any better guesses
happily considered.

Tending to happen in the UK also
even though the Royal Mail / Parcelforce often give a better service and
of course do not charge extra to send further. There has been a big
campaign in the North of Scotland about companies charging extra for
many postcode areas.

It's what happens when private firms cherry pick the most profitable stuff.

--
*That's it! I‘m calling grandma!

Dave Plowman London SW
To e-mail, change noise into sound.

On 10/05/2012 07:47 PM, zzzzzzzzzz wrote:
On Fri, 05 Oct 2012 19:00:56 -0400, Phil Hobbs
wrote:

George Herold wrote:

On Oct 5, 2:51 pm, Jeff wrote:
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs

wrote:
Yep. As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

Oscillating filament light bulb:
http://www.youtube.com/watch?v=t_DwwNVA-7Q
Whether the earths magnetic field is strong enough to induce such
oscillations is questionable.

While digging for the apparently mythical lifetime test data on
incandescent light bulbs, I've found numerous theories on why
filaments fail.

Grin, the internet as a 'fire hose' of information. I went searching
for something that contained "Philips tech. rev." and found a
reference to the following article,

H. Horster, E. Kauer and W. Lechner — The Burn-out Mechanism of
Incandescent Lamps Philips Technical Review 32,155-164, 1971.

It was referenced in "Illuminating Engineering - Page 32 - Google
Books"

But nothing about turn on failure... sigh.

Here is a patent by some of the same guys at Philips... lots of stuff
about the filament getting hottest in the middle.

http://www.freepatentsonline.com/3868159.html
(Actually a decently written patent.)

George H.

Tungsten evaporation, causing hot spots, is the most
common. One suggested that thermal cycling hardens the tungsten and
makes it brittle. Another suggested that the inrush current causes a
mechanical shock if it hits at the 60Hz peak, instead of at the zero
crossing. Yet another speculates that the temperature differential
between the hot filament, and the relatively cold mounting structure
may cause cracking.


I can believe that the filament is hottest in the middle. It's
furtherst from the support, so whatever conductive heat sinking there is
will be less, but more than that, it sees the radiative input from the
rest of the filament on both sides instead of just one.

Aren't the filaments welded to the elements at the ends? It would seem that
this would cause a narrowing. ISTR most filaments broken near the supports,
which would be counter to the hotter-in-the-middle theory.

The feedthroughs are made of Dumet, which is basically 42Ni stainless
with a borated copper coating to bind to the glass. It's much
lower-melting than the tungsten, so spot-welding them together shouldn't
affect the tungsten much.

A necked-down hot spot is a stress concentration point, and ones nearer
the support would have more mass hanging off them. When the filament
jumps at turn-on, hot spots at the ends will probably more torque applied.


My theory is that bulbs tend to fail when turned on because of the thermal
shock but only because they were about to fail anyway. Cycling, itself,
doesn't have a huge effect on longevity, certainly not a factor of two.

Sort of similar to the case of a long solenoid, whose B field at the
ends is half what it is in the middle.

Do they only burn out when energized? ;-)

I've never seen one burn out that wasn't energized. But you're the
big-iron transmitter guy. Gotta run, I have a bunch of guys coming to
the lab in a few minutes, and I have to start the coffee pot!

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 10/06/2012 04:28 AM, MB wrote:
On 06/10/2012 00:15, Phil Hobbs wrote:
"Dave Plowman (News)" wrote:

In article ,
Michael A. Terrell wrote:

Phil Hobbs wrote:

I've never had a package stolen, as far as I can recall.

Me, either. It's probably that their postal system won't come to
reasonable terms with the US postal system.

Other countries seem quite happy to use ordinary post to the UK. The US,
not. So explain that.


Probably the War of 1812.

Coming from Canada, I can tell you that the USPS is very nearly flawless
when compared with Canada Post. Those morons can't find their rear ends
with both hands and a map.


The Americans do seem generally to be used to sending a lot by courier
when we would just put in the post. Tending to happen in the UK also
even though the Royal Mail / Parcelforce often give a better service and
of course do not charge extra to send further. There has been a big
campaign in the North of Scotland about companies charging extra for
many postcode areas.


That's mostly a business etiquette thing, I think. Sending somebody a
bunch of business documents in the snail mail sort of says that their
input isn't that urgent. Letter mail here is also very secure IME.

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 Fri, 05 Oct 2012 16:02:37 -0400, "Michael A. Terrell"
wrote:


Phil Hobbs wrote:

I've never had a package stolen, as far as I can recall.

Me, either. It's probably that their postal system won't come to
reasonable terms with the US postal system.

I've never had a package stolen from the USPS, but I *have*
had one stolen from UPS.

Back in 1974 I had some stereo equipment stolen in a
break-in, and ordered a replacement to be sent UPS. The
shipment arrived while I was at work, so they left a note
that they'd try the next day. I called and said I'd pick it
up from their office after I got off work.

It was December, so there was a long line. After an
interminable wait, they said they didn't have the package...
must've gone out for delivery again by mistake. Got home,
no note. Called again and repeated everything the next day.

They finally admitted that they couldn't find the package,
and blamed it on the seasonal help. They eventually paid
for a replacement, after a lot of paperwork.

In all the years since, though, I've never had a problem.
(Of course, I became gun-shy about ordering "good stuff" in
December!)

Best regards,


Bob Masta

DAQARTA v7.10
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE Signal Generator, DaqMusic generator
Science with your sound card!

In article ,
Phil Hobbs wrote:
The Americans do seem generally to be used to sending a lot by courier
when we would just put in the post. Tending to happen in the UK also
even though the Royal Mail / Parcelforce often give a better service
and of course do not charge extra to send further. There has been a
big campaign in the North of Scotland about companies charging extra
for many postcode areas.


That's mostly a business etiquette thing, I think. Sending somebody a
bunch of business documents in the snail mail sort of says that their
input isn't that urgent. Letter mail here is also very secure IME.

Fine if 'they' want to do this and pay for it. My complaint is buying
goods from the US where I'm paying the P&P and not having the choice of a
reasonably priced service. Why would I want to pay in some cases more than
the value of the goods for postage, if I'm in no rush to receive them?

--
*A conclusion is the place where you got tired of thinking *

Dave Plowman London SW
To e-mail, change noise into sound.

On 10/06/2012 09:08 AM, Dave Plowman (News) wrote:
In ,
Phil wrote:
The Americans do seem generally to be used to sending a lot by courier
when we would just put in the post. Tending to happen in the UK also
even though the Royal Mail / Parcelforce often give a better service
and of course do not charge extra to send further. There has been a
big campaign in the North of Scotland about companies charging extra
for many postcode areas.


That's mostly a business etiquette thing, I think. Sending somebody a
bunch of business documents in the snail mail sort of says that their
input isn't that urgent. Letter mail here is also very secure IME.

Fine if 'they' want to do this and pay for it. My complaint is buying
goods from the US where I'm paying the P&P and not having the choice of a
reasonably priced service. Why would I want to pay in some cases more than
the value of the goods for postage, if I'm in no rush to receive them?


Dunno. It may have something to do with package tracking and fraudulent
claims for loss or damage. The logistics companies give you one
tracking number that works anywhere in the world, whereas the post
offices all generate confusion and duplicated numbers that make it very
hard to establish whether something got delivered, and if not, where it
went.

Here, there's lots of competition in logistics, so the service is
generally excellent and the cost very reasonable.

US postal rates are also quite low, which may make it more difficult for
them to negotiate a revenue sharing agreement with higher cost
organizations. (Canada Post is the example I'm most familiar with--at
one point quite recently, all mail from the US to Canada had to go
through the central Toronto sorting facility, even if it was a letter
sent from Vancouver to Seattle.)

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 Sat, 06 Oct 2012 07:06:22 -0400, Phil Hobbs
wrote:

On 10/05/2012 07:47 PM, zzzzzzzzzz wrote:
On Fri, 05 Oct 2012 19:00:56 -0400, Phil Hobbs
wrote:

George Herold wrote:

On Oct 5, 2:51 pm, Jeff wrote:
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs

wrote:
Yep. As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

Oscillating filament light bulb:
http://www.youtube.com/watch?v=t_DwwNVA-7Q
Whether the earths magnetic field is strong enough to induce such
oscillations is questionable.

While digging for the apparently mythical lifetime test data on
incandescent light bulbs, I've found numerous theories on why
filaments fail.

Grin, the internet as a 'fire hose' of information. I went searching
for something that contained "Philips tech. rev." and found a
reference to the following article,

H. Horster, E. Kauer and W. Lechner — The Burn-out Mechanism of
Incandescent Lamps Philips Technical Review 32,155-164, 1971.

It was referenced in "Illuminating Engineering - Page 32 - Google
Books"

But nothing about turn on failure... sigh.

Here is a patent by some of the same guys at Philips... lots of stuff
about the filament getting hottest in the middle.

http://www.freepatentsonline.com/3868159.html
(Actually a decently written patent.)

George H.

Tungsten evaporation, causing hot spots, is the most
common. One suggested that thermal cycling hardens the tungsten and
makes it brittle. Another suggested that the inrush current causes a
mechanical shock if it hits at the 60Hz peak, instead of at the zero
crossing. Yet another speculates that the temperature differential
between the hot filament, and the relatively cold mounting structure
may cause cracking.


I can believe that the filament is hottest in the middle. It's
furtherst from the support, so whatever conductive heat sinking there is
will be less, but more than that, it sees the radiative input from the
rest of the filament on both sides instead of just one.

Aren't the filaments welded to the elements at the ends? It would seem that
this would cause a narrowing. ISTR most filaments broken near the supports,
which would be counter to the hotter-in-the-middle theory.

The feedthroughs are made of Dumet, which is basically 42Ni stainless
with a borated copper coating to bind to the glass. It's much
lower-melting than the tungsten, so spot-welding them together shouldn't
affect the tungsten much.

Welding5 is welding. Metal has to flow, no?

A necked-down hot spot is a stress concentration point, and ones nearer
the support would have more mass hanging off them. When the filament
jumps at turn-on, hot spots at the ends will probably more torque applied.

My theory is that bulbs tend to fail when turned on because of the thermal
shock but only because they were about to fail anyway. Cycling, itself,
doesn't have a huge effect on longevity, certainly not a factor of two.

Sort of similar to the case of a long solenoid, whose B field at the
ends is half what it is in the middle.

Do they only burn out when energized? ;-)

I've never seen one burn out that wasn't energized.

OK, perhaps I sh6ould have said *as* they-re energized (to keep th6e corollary
with light bulbs burning out when turned on).

But you're the big-iron transmitter guy.
^^^^^^^^^^^

Huh? I think you have me confused with someone else.

Gotta run, I have a bunch of guys coming to
the lab in a few minutes, and I have to start the coffee pot!

Most important. Get the good stuff.

On Sat, 06 Oct 2012 09:28:03 +0100, MB wrote:

On 06/10/2012 00:15, Phil Hobbs wrote:
"Dave Plowman (News)" wrote:

In article ,
Michael A. Terrell wrote:

Phil Hobbs wrote:

I've never had a package stolen, as far as I can recall.

Me, either. It's probably that their postal system won't come to
reasonable terms with the US postal system.

Other countries seem quite happy to use ordinary post to the UK. The US,
not. So explain that.


Probably the War of 1812.

Coming from Canada, I can tell you that the USPS is very nearly flawless
when compared with Canada Post. Those morons can't find their rear ends
with both hands and a map.


The Americans do seem generally to be used to sending a lot by courier
when we would just put in the post.

"Courier"? Do you mean "next day" services like FedEx and UPS? Yes, often
time is money. "Couriers" are sometimes (rarely) used for intra'-city
delivery when hours count. Intrest on a megabuck pays for courier service.

Tending to happen in the UK also
even though the Royal Mail / Parcelforce often give a better service and
of course do not charge extra to send further. There has been a big
campaign in the North of Scotland about companies charging extra for
many postcode areas.

Your point?

On 10/06/2012 11:14 AM, zzzzzzzzzz wrote:
On Sat, 06 Oct 2012 07:06:22 -0400, Phil Hobbs
wrote:

On 10/05/2012 07:47 PM, zzzzzzzzzz wrote:
On Fri, 05 Oct 2012 19:00:56 -0400, Phil Hobbs
wrote:

George Herold wrote:

On Oct 5, 2:51 pm, Jeff wrote:
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs

wrote:
Yep. As I understand it (possible wrong), AC filaments break in the
middle, mostly from vibration flexing.

I don't think so, because there's no mechanism for that, as I said. The
wire is fully annealed at all times, so there's no possibility of
progressive fatigue failure.

Oscillating filament light bulb:
http://www.youtube.com/watch?v=t_DwwNVA-7Q
Whether the earths magnetic field is strong enough to induce such
oscillations is questionable.

While digging for the apparently mythical lifetime test data on
incandescent light bulbs, I've found numerous theories on why
filaments fail.

Grin, the internet as a 'fire hose' of information. I went searching
for something that contained "Philips tech. rev." and found a
reference to the following article,

H. Horster, E. Kauer and W. Lechner — The Burn-out Mechanism of
Incandescent Lamps Philips Technical Review 32,155-164, 1971.

It was referenced in "Illuminating Engineering - Page 32 - Google
Books"

But nothing about turn on failure... sigh.

Here is a patent by some of the same guys at Philips... lots of stuff
about the filament getting hottest in the middle.

http://www.freepatentsonline.com/3868159.html
(Actually a decently written patent.)

George H.

Tungsten evaporation, causing hot spots, is the most
common. One suggested that thermal cycling hardens the tungsten and
makes it brittle. Another suggested that the inrush current causes a
mechanical shock if it hits at the 60Hz peak, instead of at the zero
crossing. Yet another speculates that the temperature differential
between the hot filament, and the relatively cold mounting structure
may cause cracking.


I can believe that the filament is hottest in the middle. It's
furtherst from the support, so whatever conductive heat sinking there is
will be less, but more than that, it sees the radiative input from the
rest of the filament on both sides instead of just one.

Aren't the filaments welded to the elements at the ends? It would seem that
this would cause a narrowing. ISTR most filaments broken near the supports,
which would be counter to the hotter-in-the-middle theory.

The feedthroughs are made of Dumet, which is basically 42Ni stainless
with a borated copper coating to bind to the glass. It's much
lower-melting than the tungsten, so spot-welding them together shouldn't
affect the tungsten much.

Welding5 is welding. Metal has to flow, no?

Sure, but not the tungsten, just the steel. The melting point
difference is more than that between copper and solder, so it's more
like brazing than normal welding.


A necked-down hot spot is a stress concentration point, and ones nearer
the support would have more mass hanging off them. When the filament
jumps at turn-on, hot spots at the ends will probably more torque applied.

My theory is that bulbs tend to fail when turned on because of the thermal
shock but only because they were about to fail anyway. Cycling, itself,
doesn't have a huge effect on longevity, certainly not a factor of two.

Sort of similar to the case of a long solenoid, whose B field at the
ends is half what it is in the middle.

Do they only burn out when energized? ;-)

I've never seen one burn out that wasn't energized.

OK, perhaps I sh6ould have said *as* they-re energized (to keep th6e corollary
with light bulbs burning out when turned on).

But you're the big-iron transmitter guy.
^^^^^^^^^^^

Huh? I think you have me confused with someone else.

Gotta run, I have a bunch of guys coming to
the lab in a few minutes, and I have to start the coffee pot!

Most important. Get the good stuff.

Stew Leonard's Espresso Roast, roasted fresh daily in sunny Yonkers.
Best beans I've ever come across, and worth the trip. Always a crowd
pleaser.

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