On 6 Oct 2012 23:31:51 GMT, Jasen Betts wrote:

yeah, it would be a good project for the mythbusters, I'd love to see
a slow motion film of an incandescent lamp failing at turn-on.
but could they affor do dedicate their fast camera for long enough.

Due to the apparently lack of data and my curiosity, I was thinking of
throwing together a crude experiment. Two lamp bases, two 40 watt
clear envelope incandescent lamps, two SSS (solid state switches), and
some kind of pulse generator. 30 seconds on should be enough to get
the filament hot enough for sublimation. 30 seconds off should be
enough for it to cool down for a cold start (I need to check this with
an IR thermometer).

However, I have no intention of running this test for 1000+ hours.
Instead, an accelerated life test can be done with higher than normal
voltages.
http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3544HPX_Catalog_2_11_09.pdf
For halogen bulbs, they use:
Life = (Vdesign / Vapplied)^12.0 * Life at design voltage
For a 1000 hr lamp running at 120% of the rated voltage, the life
might be:
life = (1/1.2)^12 * 1000 = 112 hrs
which is more reasonable for my tinkering and for Mythbusters. With
power cycling, the life will be even less. I should have a Variac
somewhere in my junk pile.

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