Amplifier Circuit for Thermopile

Question

I would like to build a circuit for reading temperature from a thermopile temperature sensor. I found this application reference for the circuit (page 6, Single power supply type with thermistor). However I do not understand how to calculate the resistance value (Ra, Rb, Rc).

At step 2, it requires:

1) Measure the thermopile detector output voltage (Voutmin) at Tmax.

2) Measure the thermopile detector output voltage (Voutmax) at Tmin.

What does that mean? How can I measure the thermopile output voltage before I build the circuit?

Thank you very much

Answer 1

It looks like the circuit they're having you design is to compensate the output for the temperature of the thermopile itself.

I think what they want you to do, is the heat or cool the thermopile to the min and max operating temperatures, and measure it's output at those points (Like with a multi-meter). Then you take those values and use them to design the compensation circuit.

Answer 2

You might simply digitize the thermopile output voltage with a high-resolution ADC, and your task may become simpler. But the learning is probably the purpose of the project.