How to work out the gain of my op-amp diagram

Hi all, ive just started studying electronics an im struggling with a question.
im trying to find out how to work out the gain on my sensor circuit and the V-out .
The temp sensor has a resistance of 5k at 0degrees, 2.5k at 20degrees, 2k at 30degrees and finally 1.8k at 40degrees.
From what i can gather, the whole circuit can be split in 2, with an opamp in each section, but im not sure on this..
Ive been trying to figure this out for 3 days now, and have seen so many confusing ways, any help would be greatly appreciated, below is the link to the diagram in question.

The gain is the following:

5V * (( Rtheom/(Rtheom + 5K)) * 2, or 10V*((Rtheom/(Rtheom + 5k))

So lets say your thermistor (temp dependent resistor) is 10K at room temp 23C, that would make your output voltage 6.67V.

1st opamp has a gain of 2, the second is unity. Oh thanks for providing the schematic, schematics help so very much.

Hi earl, sorry but what is "Rtheom"? Is it the thermistor? Also, how is the gainnworked out to 2?

I understand the above as, V-In * thermistor/thermistor + 5k * gain ?

Many thanks, rich

Yes Rtheom is the variable resistor. I won't explain why the 1st amplifier has a gain of 2, you can do a Wilki search on non-inverting opamps to get that.

The output voltage on the 2nd opamp can go from zero to 10V assuming the opamp has a supply voltage greater than 10V although I am sure the thermistor doesn't vary from short to open. If you want to know what to expect you need to look up the value of the thermistor at the temperature endpoints you expect then just plug that in and you will get the output voltage you should see at those points.

Hope that helps.

Hi Earl, how did you get 6.67v output using the formula in your first reply with a 5 or 10volt input, as i seem to get 20v ?

# If your node at the thermistor & 5K resistor is 10V and your amplifier supply voltage is 20 volts you will get 20V.
Please ,m all node voltages and advise what those are especially the (+) & (-) nods to the amplifiers.

Hi, i got it now. Many thanks for your help.