filament temperature 1

[230842]

I am looking for an easy to use and cheap method, or equipment, allowing to measure filament temperature in operating incandescent lamps (tungsten filaments). High accuracy in not requested; plus minus 100º celsius uncertainty is allowed. Julian

 

[nbucska]

100 degree seems to be fairly accurate to me...

You can measure the ratio of cold resistance to hot
resistance.

Better would be filter out two colors (e.g. blue/red )
and measure their ratio.

Wjy do you need it ? perhaps there is an other way...
<nbucska@pcperipherals.com>

 

[proff]

You used to be able to get diffraction gratings that could measure the temperature of a bulb filament accurate to 10 degrees or so, I think they were called Bragg gratings. They were film/glass with lines accurately spaced. Using two of these you could identify the wavelength of the light emanation and calculate the temperature. I haven't seen them for 30 years or so. They were very cheap and simple to use.

 

[hcfl]

Question for Proff:

What was the setup with the two Bragg gratings used to get the filament temperature?

 

[IRstuff]

To achieve the level of accuracy you're alluding to requires curve fitting the spectral output to the ideal blackbody, which requires a spectroradiometer and lots of time and money.

If it's a standard incandescent bulb, a diffraction grating gets you the spectrum, but you'll need the relative spectral output at each wavelength, which is what allows you to figure out the color temperature.

What is the specific need, e.g., what is the applicability of the information?

Are you looking for color temperature? Color temperatures of typical incandescent bulbs are all considerably lower than something like the 2856 K bulb used in high performance electro-optical testing.

TTFN

 

[230842]

My purpose was to teach my pupils, by Lab meassurements, the temperature dependence of electrical conductors getting practical curve resistance-temperature.
It seems to be a very dificult objective, so any other suggestion will be appreciated.

Julian

 

[IRstuff]

Perhaps either standard carbon resistors or platinum resistance thermistors (PRTs) might be more apropos. In fact, PRTs might be interesting in of themselves, since there's the interesting duality of setting the temperature vs. setting the power and inferring the same temperature.

This type effect is used in a number of electrically calibrated optical power instruments.

TTFN

 

[nbucska]

from cold to hot you can get easily 10 times variation
a voltmeter, an ammmeter and a variable power supply
should be enough.

<nbucska@pcperipherals.com>

 

[230842]

Thanks nbucska. The problem is to meassure temperature

Julian

 

[lilygaby1]

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lily