🚀 go-pugleaf

On Oct 5, 2:51 pm, Jeff Liebermann <je...@cruzio.com> wrote:
> On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs
>
> <pcdhSpamMeSensel...@electrooptical.net> 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     je...@cruzio.com
> 150 Felker St #D    http://www.LearnByDestroying.com
> Santa Cruz CA 95060http://802.11junk.com
> Skype: JeffLiebermann     AE6KS    831-336-2558

G