On Friday, March 21, 2014 7:29:09 PM UTC, Harry Bloomfield wrote:
After serious thinking Johny B Good wrote :
I'm afraid to say this, but that last paragraph is basically a load
of bull****. Regardless of 'poor quality of early filaments' the
design criteria is still affected by the same physical laws that
determine the life versus luminous efficacy trade offs made with
today's high quality filaments.
Is exactly right!
There has been little if any improvement or development in lamps and
filaments, since the 1950's maybe even back to the 1920's.

The improved quality of filament just allows for an improved luminous
efficacy for a given lamp life (1000 hours being the standard lamp
life arrived at all those years ago as offering the best TCO between
the electricity and lamp replacement costs).
They were quoting 1.00 hours back in the 1950's and coiled coils.

IIRC the last significant change was the coiled coil, introduced in the 1930s. If you buy vanilla GLS you're getting 1930s technology.

There have been other developments since, but either very minor (higher temp rated cement enabling smaller envelopes) or large enough to produce new lamp types, halogen & xenon.


NT