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10/14/10 13:51
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 		 #179108 - Thermistors aren't such bad...
Responding to: ???'s previous message
Per said:
First off you must separate precision from resolution. A therminstor has lousy precision. The tolerances are large. The drift is large.

A good NTC for temperature measurement has a long term drift deltaR25/R25 of less than 2%. This gives an error of less than 0.5°C at 25°C, which is good enough for many applications:

http://docs-europe.origin.electrocomponents.com/webdocs/0...e29342.pdf

If actually a precision of 0.1°C is needed, I would use a platinum RTD.

Kai Klaas

List of 24 messages in thread
TopicAuthorDate
Measure temperature @0.1deg resolution using thermistor            01/01/70 00:00      
   Sorry - doesn't work            01/01/70 00:00      
      Thermistors aren't such bad...            01/01/70 00:00      
         Remember the original requirement of 0.1°C            01/01/70 00:00      
   Resolution is not there...            01/01/70 00:00      
      What about the Termistor            01/01/70 00:00      
      RE: Resolution is not there...            01/01/70 00:00      
         one-wire sensors are still quite expensive than thermistors            01/01/70 00:00      
            Thermistor Vs one-wire sensor cost            01/01/70 00:00      
               Your processor has a voltage reference good enough?            01/01/70 00:00      
                  Voltage reference            01/01/70 00:00      
                     That voltage reference has large error...            01/01/70 00:00      
                  Vref is Not Needed            01/01/70 00:00      
                     Depends            01/01/70 00:00      
                        Ah but,            01/01/70 00:00      
                           Still not trivial            01/01/70 00:00      
         The normal fluke doesn't give 0.1C correct readings            01/01/70 00:00      
         I think your customer ...            01/01/70 00:00      
            quite common problem with resolution/precision            01/01/70 00:00      
         linearing only solves one issue            01/01/70 00:00      
            Precision            01/01/70 00:00      
               hm            01/01/70 00:00      
               Not an opamp            01/01/70 00:00      
               Comparison with Fluke a big problem            01/01/70 00:00      

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