PicDude wrote:
> I'm searching for a fast temp sensor for measuring ambient air temperature
> (with some overhead) -- say -10deg-C to 120deg-C.  1% accuracy or better.
> 
> There are a lot of sensors that meet this numerical criteria, but what types
> of temps sensors are *fast*?  I usually don't see response time listed in
> the datasheets (and not even sure what the parameter is for response time),
> and I don't have a specific value for how fast it should be, but I want to
> compare various sensor types and start investigating/experimenting with the
> fastest of these.
> 
> I did find "fast response RTD's" and wondering how they compare (speed-wise)
> to other alternatives such as semiconductor sensors.  I expect the plastic
> housings for TO-92 types and similar would be enough of an insulator to
> significantly increase the response time.  Will the metal can versions
> (TO-39 IIRC) be considerably faster?  Open element sensors and low-mass
> sensors should be fast.  But I'm sure I am missing a lot of other
> possibilities here.  
> 
> Any links/clues on this?
> 
> Thanks,
> -Neil.
> 

Find something in a very small package and then use more than one to
achieve high statistical accuracy.
i.e. n samples with 1 degree accuracy would give you 1/sqrt(n) accuracy
 IIRC.

You could possibly do a derivative calculation to achieve quicker
estimates of the ending reading
i.e: You read 105 degrees. The dT/dt is -4 degrees. You might predict
that the future sample is likely to be closer to 101 degrees or that the
ACTUAL temperature is lower than 105 because you can account for your
sensor's thermal mass.
"YMMV"

-
Martin
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