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## Homework Statement

Currently writing a report about a Wheatstone Bridge circuit with RTD sensor. The sensor is to work between 0°C and 100°C and output 0 mV to 10 mV.

R

_{x}has a nominal resistance, R

_{n}of 100 Ω, V

_{s}=10 V and α=0.00385 °C

^{-1}. Therefore R

_{T}= 138.5 Ω

Assuming R

_{T}is in the bottom right of a diamond circuit, R

_{1}to the bottom left, and R

_{2}and R

_{3}are at the top, I have calculated that for a balanced equation R

_{1}=100 Ω and R

_{2}=R

_{3}=3608.1 Ω

The question asks us to vary the values of R

_{2,3}and note the changes, such as if they are set

a low value i.e. R

_{2,3}=10 Ω, the output loses it's linearity.

I also noticed that the peak output voltage occurs around 118 Ω, and have a graph to show this, however I don't have the knowledge to calculate the R

_{max}and V

_{max}mathematically, only approximate it.

## Homework Equations

## The Attempt at a Solution

My inclination was to reduce the formula to a polynomial of one variable and solve for 0 as you would for a quadratic equation. Inserting the values V

_{s}=10, R

_{x}=138.5, R

_{1}=100 and assuming R

_{2,3}=R I have reduced the equation to:

385R/(R

^{2}+238.5R+13850)

I have no idea where to go from here. Even mathcad sputters to a halt when trying to graph the equation.

Many thanks for any help!

Edit:

I've just noticed in the above equation R

_{1}and R

_{2}are reversed.

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