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.
Rx has a nominal resistance, Rn of 100 Ω, Vs=10 V and α=0.00385 °C-1. Therefore RT = 138.5 Ω
Assuming RT is in the bottom right of a diamond circuit, R1 to the bottom left, and R2 and R3 are at the top, I have calculated that for a balanced equation R1=100 Ω and R2=R3=3608.1 Ω
The question asks us to vary the values of R2,3 and note the changes, such as if they are set
a low value i.e. R2,3=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 Rmax and Vmax mathematically, only approximate it.
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 Vs=10, Rx=138.5, R1=100 and assuming R2,3=R I have reduced the equation to:
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!
I've just noticed in the above equation R1 and R2 are reversed.