Need formulas for OP AMP calculation Vout

Thread Starter


Joined Aug 29, 2010
I've created in NI Multisim 11 project PT1000 and OP Amp TLC271CP for measuring temperature from-20C to +200 C. It should formula for calculation Vout and to check whether this model can work in reality. I am not electrician but my Hobby's electronics. Intervals Vout (ADC) is 0-5 V. Microcontroller was ATMega 16, but that does not meet, if resolution ADC ATMega 16 is not good I think to use SPI MCP3201 12-bit ADC. Further should formula for calculation RT (R7) on bases Vout.



Joined Aug 16, 2010
I'm having a little trouble understanding your post. Just a language problem I think.

I believe you are asking for a formula for the output voltage of your circuit as a function of R7.

The formula is: Vout = [48.55 / (1 + 6.19k/R7) ] - 6.1V

If you substitute the value for R7 given in your simulation, this formula gives 4.64V which is very close to the simulation result. The error is probably due to me rounding off values too early in the calculation. Its late and I'm tired so I don't want to go back and fix this right now.

If you want details of how to get this formula I'll be happy to share.