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What type of curve is this? Is there any formula to plot the curve?

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udhay_cit

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I need to display temperature by measuring the current (Indirect temperature measurement). The current to temperature readings are not perfect linear but its a very smooth curve. Now I need a mathematical formula to convert the current into temperature. All I need to enter the starting & end value. Is it possible? Can some one can give a simple formula, it will be very helpful to me.

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Udhay
 

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chuckey

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for a curve of this type I = mT + yT^k + C . i.e. the current may have a constant offset (C) and a component directly linked to T (mT) and an exponential component related to T (yT^k).
So replot I v T using logs, this gives you logI = (log m + logT) + {logy +( k LogT )} +log C. This will give you a linear "curve" whose slope is k. taking two extreme values you can work out the differences of the slope , hence giving you logm and logC.
Substitute these anti logged values into the original formula will give you the correct formula. I don't know how you are going to generate the exponential coefficient.
Frank
 

kripacharya

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If you really want a formula as an end result, then read this for pointers.

Alternately if you simply need to convert current to temperature on a uC or computer, it might be faster & easier to simply have a look-up table with your values, and use interpolation for intermediate values - keeping in mind that every interval has a different slope or conversion factor.
 
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