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Re: Light bulb science and technology



At 17:44 3/15/98 -0400, Ludwik wrote:
How do they manufacture tungsten filaments which are double-coiled?
Was it always like this? I remember seeing single coils when I was a kid.
But it did not occur to me to look through a magnifying glass.


They start with single-coiled wire!

Or (one step back) with a thick wire extruded or swaged to size.

Or ( two steps back) from a sintered tungsten powder bar, amalgamated
with extended Joule heating in an inert atmosphere, then hot worked.

Or (three steps back) from fine tungsten powder with a little thoria for
sag-resistance.

But let's get serious: begin with Wolframite or Scheelite....

Whatcott Altus OK