AVR-Chat

Hello Kathy,

The easy answer for me is : NTC in a half-bridge. I have used calibrated 
10k@25°C bead types from RS components to within 0.5°C, over a range 
10-40°C, and this without additional linearisation beyond the half-bridge.

RS databook characteristics support measurement to within 0.2°C  - i.e. 
this accuracy after calibrating with one then inserting another. I've 
also checked this - it's about right. I calibrated my circuits (with 
<50ppm/°C high stab resistors) with two NTCs in a water bath, then 
applied them to 32 NTCs fresh out of the packaging.

I am sure that your precision specification would be obtainable from 
individual sensor calibration (now, this may be a challenge...)

John Stiekema


Kathy Quinlan wrote:

> Hi all,
> 
> I need to measure tempretures around 36C with the best acuracy I can 
> get, I would like to measure with a precision of 0.1C so I guess I need 
> acuracy or ~0.05C.
> 
> I am looking at IR based units, but I can not see why a Type K 
> thermocouple can not be used and just calibrated Span is roughly 33-46C, 
> so linearisation is not such a big issue for such a small span I THINK, 
> correct me if I am wrong.
> 
> Any ideas ? will Type K get me there ? or do I need to do the IR probe ?
> 
> Cost will be a factor as we are looking at 1-100K units (I love vague 
> customers)
> 
> Regards,
> 
> Kat.