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 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 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 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

Phil Hobbs wrote:
[......]

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

Sorry to hijack this thread but I have an actual electronics repair
question: how do I go about getting my old AIWA CX-NA10 stereo system to
read CD's again? Is the lazer bad? It detects the cd and spins up but
wont play it.



--
http://howlingforjustice.wordpress.com
www.snuhwolf.9f.com|www.savewolves.org
_____ ____ ____ __ /\_/\ __ _ ______ _____
/ __/ |/ / / / / // // . . \\ \ |\ | / __ \ \ \ __\
_\ \/ / /_/ / _ / \ / \ \| \| \ \_\ \ \__\ _\
/___/_/|_/\____/_//_/ \_@_/ \__|\__|\____/\____\_\

On 10/06/2012 12:51 PM, §ñühwö£f wrote:
Phil Hobbs wrote:
[......]

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

Sorry to hijack this thread but I have an actual electronics repair
question: how do I go about getting my old AIWA CX-NA10 stereo system to
read CD's again? Is the lazer bad? It detects the cd and spins up but
wont play it.



You're no fun anymore.

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

Phil Hobbs wrote:
On 10/06/2012 12:51 PM, §ñühwö£f wrote:
Phil Hobbs wrote:
[......]

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

Sorry to hijack this thread but I have an actual electronics repair
question: how do I go about getting my old AIWA CX-NA10 stereo system to
read CD's again? Is the lazer bad? It detects the cd and spins up but
wont play it.



You're no fun anymore.

Cheers

Phil Hobbs


Uh huh. I fixed it somewhat by fiddling with the screw behind the back
cover. G00gle told me how. You lot are obviously quite useless.

nods


--
http://howlingforjustice.wordpress.com/
www.friendsofanimals.org |www.snuhwolf.9f.com|
_____ ____ ____ __ /\_/\ __ _ ______ _____
/ __/ |/ / / / / // // . . \\ \ |\ | / __ \ \ \ __\
_\ \/ / /_/ / _ / \ / \ \| \| \ \_\ \ \__\ _\
/___/_/|_/\____/_//_/ \_@_/ \__|\__|\____/\____\_\

On Sat, 06 Oct 2012 10:51:47 -0600, §ñühwö£f
wrote:

Phil Hobbs wrote:
[......]

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

Sorry to hijack this thread but I have an actual electronics repair
question: how do I go about getting my old AIWA CX-NA10 stereo system to
read CD's again? Is the lazer bad? It detects the cd and spins up but
wont play it.

Have you taken it apart yet? Try cleaning the lens. In a dirty,
smoky or wet environment the lenses can become coated with stuff.

default wrote:
On Sat, 06 Oct 2012 10:51:47 -0600, §ñühwö£f
wrote:

Phil Hobbs wrote:
[......]

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

Sorry to hijack this thread but I have an actual electronics repair
question: how do I go about getting my old AIWA CX-NA10 stereo system to
read CD's again? Is the lazer bad? It detects the cd and spins up but
wont play it.

Have you taken it apart yet? Try cleaning the lens. In a dirty,
smoky or wet environment the lenses can become coated with stuff.


I had it "working" a little after all that and an adjustment to the
potentiometer on the back of the lazer as instructed. However it would
only read one specific CD and scratched some CD's when it went thru its
ejection cycle (disks would not spin down before ejection!) so I removed
the tray and wont use it anymore. Further research indicated AIWA was
part of a class action lawsuit in the 90's due to their CD players being
crap. They're out of business now anyway. Good riddance.

--
http://howlingforjustice.wordpress.com
www.snuhwolf.9f.com|www.savewolves.org
_____ ____ ____ __ /\_/\ __ _ ______ _____
/ __/ |/ / / / / // // . . \\ \ |\ | / __ \ \ \ __\
_\ \/ / /_/ / _ / \ / \ \| \| \ \_\ \ \__\ _\
/___/_/|_/\____/_//_/ \_@_/ \__|\__|\____/\____\_\

"Phil Hobbs" wrote in message
m...
SNIP

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.

Just crimped over AFAIK. Should work fine - the softer metal will cold form
around the tungsten see

http://upload.wikimedia.org/wikipedi...8/Filament.jpg


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

They can, but no very often.

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