Go Down

Topic: Measuring the resistance and thus temperature of an RTD (Read 1 time) previous topic - next topic


I have a soldering pencil which has an integrated PTC RTD built in. The temperature of the RTD can be represented using this equation y = 0.0056x^2+4.9382X-239.43 where x is the resistance of the RTD and y is the temperature in Celsius. The resistance would vary from 50 to 100 ohms (its a relatively low resistance for an RTD).

Could you please provide me with a way to measure the resistance of the RTD giving the greatest resolution to the arduino measuring it? (ie use all 1024 voltage levels measured with the arduino's analogRead() )

Thank you in advance.


You would not get much better resolution, if you 'd carefully scale input  to 0-5 range using OPA,  compare to simple R - RTD voltage divider.
Other options,  use external ADC, 16 - 24 bits, or you may dig for Atmel app. note explaining oversampling technics AVR121.
For update rate 3 Hz , which is (IMHO) o'k with temperature measurements, they give this numbers:

Voltage        Oversa-       Right      Ideal           Ideal voltage           Maximum
resolution     mpled      shifted decimated      representation         Bandwidth

~75 uV       4096X         6X        32413             2.4729V               ~3Hz (1)


Magician could you please explain to me the term OPA and the table you posted below?
Thanx again


Table from AVR121, google for it. OPA - operational amplifier: http://en.wikipedia.org/wiki/Operational_amplifier


Go Up

Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

via Egeo 16
Torino, 10131