Re: temperature of filament

In article <y93k5l8yvrl.fsf@xxxxxxxxxxxxxxxxxxxx>, Allan Adler wrote:
Allan Adler <ara@xxxxxxxxxxxxxxxxxxxx> writes:

What is the easiest and cheapest method to determine the temperature of
a filiment in a light bulb or electron tube (vacuum or gas filled)?

I seem to think that usually the "best bet" is determining resistance at
room temperature and resistance at operating temperature. Find the ratio
of these, then find a "properties of tungsten" chart.

This will oversimplify things by assuming the filament temperature is
uniform from one connection point to the other, but my experience is that
this does better than anything else.
The main shortfall here is that not quite all of the filament will be at
"full operating temperature". I seem to think that actual "operating
region" of the filament will have temperature only a few to a few 10's
of K hotter than indicated by resistance ratio between hot and cold when
filament lenghth is nice and long so that no more than a small percentage
is greatly cooler than "operating temperature". The biggest error I found
here so far is contact resistance to lamps whose cold resistance is being
determined.

- Don Klipstein (don@xxxxxxxxx)
.

Relevant Pages

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