On 2/1/08, Phillip Coiner <pcoiner@gpssource.com> wrote:
> Hi all
>
> I need to measure temperature of a chemical reaction that I'm told can reach
> as high as 400F (204C)
>
> I have done something similar before in a couple of designs using
> thermistors with a voltage across them and an AD converter to read the
> voltage change with temp.
>
> This was only to tell me if the temp gets higher than 150C to report an
> error/failure so it wasn't the most accurate temperature measurement ever
> made of that I'm certain.
>
> It worked fine but I only learned enough/remember enough to get into trouble
> now.
>
> This time I need a fairly quick response time and I need to have less than
> one degree of error across the range i.e. 0 to 204C.   (Lets say 0 to 250C
> for the sake of discussion)
>
>
>
> I know nothing about selecting a thermistor verses a thermocouple but I was
> told that for temps above 150C that I might need to use a thermocouple.
>
> Can any of the resident wise men direct me to some resources to read or
> offer any advice for selecting a thermistor vs a thermocouple?
>
> I'm going to go to the microchip web site later today and grep around for
> any application notes?
>
> I be grateful for any advice or direction anyone here has to offer.

There are some good solid state RTDs (looking like a diode and acting
like a RTD).
But for 1C accuracy over 200C will need calibration.
Search for KTY84 (but there are also too from Siemens, Infineon, NXp etc).

Vasile
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