From: jim.richards65@yahoo.com   
      
   Ralph,   
      
   I haven't heard of  "resistance temperature detector" are they also   
   referred to as thermistors(sp)?   
      
   Curbie   
   >   
   >"Curbie"  wrote in message   
   >news:lsb7g7hop74d4fjt9144pn9gb18fe6i65c@4ax.com...   
   >> Hi Jim,   
   >>   
   >> Good stuff as always.   
   >>   
   >> I did tried multiple thermocouples to even out the variations in their   
   >> alloy compositions and statistical averaging to average out noise on   
   >> the wires, then calibrated with temperature sensors, and was never   
   >> able to get the thermal couples to maintain <1C in relation to the   
   >> temperature sensors. Probably just me, through I got 2 batches a 3   
   >> DS18B20 temperature sensors from 2 two different sources and they read   
   >> <.5C between all senses between both batches, just cheapo   
   >> thermocouples I guess.   
   >>   
   >> Curbie   
   >>   
   >>   
   >   
   >The TC is not very accurate.  Where I work we have instruments tracable to   
   >the NIST (think that is the right leters).  We have in usage several   
   >thousand TCs.  Mostly J types.  The place we get most of them from specify   
   >the accuarcy of  plus/minus 3 deg C at 300 deg C for us.  They ordered a big   
   >roll of TC wire for us and most of them are cut from the same roll.  This is   
   >done so that hopefully they will all be off by about the same ammount.  Some   
   >are dual and triple elements in the same tube that is less than 1/4 of an   
   >inch in diameter.  Sometimes they are very close, but I have measured them   
   >to be about 2 deg C differant at close to 300 deg C.   
   >   
   >We do use some RTDs.( resistance temperature detector).  They are suspose to   
   >be more accurate,but do not seem to be as reliable and you must make sure   
   >the connections are very good.   
   >   
      
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