- #1

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Wikipedia shows the formula on this page (http://en.wikipedia.org/wiki/Callendar-Van_Dusen_equation) but I don't know how to figure out any of the coefficients or anything.

Thanks for any help I can get!

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- Thread starter ISX
- Start date

- #1

- 120

- 0

Wikipedia shows the formula on this page (http://en.wikipedia.org/wiki/Callendar-Van_Dusen_equation) but I don't know how to figure out any of the coefficients or anything.

Thanks for any help I can get!

- #2

- 1,255

- 3

Do you mean using a thermistor, or just by plugging into any random piece of electronics?... I am trying to figure out how to make a calculator to figure out what temperature something is at based on the ohm reading I get....

The answer depends sensitively on your situation.

- #3

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Guess it would be this equation then. http://en.wikipedia.org/wiki/Steinhart–Hart_equation

Temperature range of interest would be -40 to 212F. I just need help on the coefficient stuff.

- #4

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- #5

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73.00 5.0

65.00 6.6

56.00 13.0

39.00 28.0

25.80 43.0

24.57 46.2

18.96 53.7

- #6

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- #7

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It is a thermistor..

- #8

Q_Goest

Science Advisor

Homework Helper

Gold Member

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Hi ISX

For the values you provided, the chart is rather limited and I wouldn't suggest using it for values outside the tested limits, but attached is what you'd get. I'd suggest getting some more measurements, especially at the limits of your intended range (ie: test in boiling water, 212 F, and at -40 F).

Another alternative is to get an equation from the thermistor manufacturer.

Do you have Excel or some other spreadsheet program? Just put the numbers you have for temperature and resistance and have the program do the curve fit to a polynomial for you.I just need help on the coefficient stuff.

For the values you provided, the chart is rather limited and I wouldn't suggest using it for values outside the tested limits, but attached is what you'd get. I'd suggest getting some more measurements, especially at the limits of your intended range (ie: test in boiling water, 212 F, and at -40 F).

Another alternative is to get an equation from the thermistor manufacturer.

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