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Topic: NTC Thermistor vs LM35 (Read 4072 times) previous topic - next topic

Gadget999

Wanted to ask some opinions on the pro's and cons of each


RuggedCircuits

Thermistors are very cheap, in the ballpark of $0.20. They're not very precise and their resistance change with temperature is non-linear, so you have to do a little "work" in your software to figure out the temperature.

Active devices like the LM35 are more expensive (>$1) but are more precise and provide a linear voltage-vs-temperature characteristic making it easier to figure out the temperature.

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The Ruggeduino: compatible with Arduino UNO, 24V operation, all I/O's fused and protected

johnwasser

The LM35 is calibrated.  The thermistor has to be calibrated against some known-good temperature standards.
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illillillill

if you want the temperature in Celcius and i have the LM35, just use this code:

Code: [Select]
tempC = analogRead(tempPin);
  tempC = (5.0 * tempC * 100.0)/1024.0;


and u'r pretty much all set,  with the NTC/PTC u'll need to make a circuit and even then you wont be able to do anything nearly as simple as this code.

Gadget999

cheers for the code

is there any other alternative other than a thermocouple that can read a higher temperature

illillillill

you want to read above 155C ? 

you could try this:
http://www.omega.com/rtd.html

but i dont know anything about it. i can just see the ratings.  if you need more advanced help on temperature i can refer you to the sensor forum in arduino: http://arduino.cc/forum/index.php/board,10.0.html 

Gadget999

ty

looks like a good alternative

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