Needs help to understand this opamp circuit

Thread Starter

sid7007

Joined Nov 18, 2015
1
upload_2016-12-1_14-47-15.png


R12 is the 10K thermister, I need to understand that how we derive equation for the relationship between R12 and Vout for firmware design in software.

Thanks in advance for your help
 

#12

Joined Nov 30, 2010
18,224
Between R4 as positive feedback and an undefined V2, I don't know what to make of this. The way I did it, R4 doesn't exist. Depending on accuracy required, you might need the chart for the thermistor. Use that to make a look-up table, or a linearizing circuit as per the thermistor manufacturer. Your U2 (without R4) is a simple gain of 2 followed by a 0.05 second time constant and a buffer amplifier.
 
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