### Berkeley Electronic Interfaces Course – Robot Module 2 – Wheatstone Bridge

This second module on the EE40LX course is about using a Wheatstone bridge: any resistive sensor could be used in the bridge. The final robot we build in the course has two photocell “eyes.”

One key note on Wheatstone bridge is that, if one would like the swing of $V_{out}$ to include both positive and negative voltages, one will have to make sure the choices of R1, R2, R4 to have a value between the lower and upper limit of R3, which is a photocell (VT90N1) in this case.

Photocell used here is EXCELITAS TECH VT90N1 LDR, 200KOHM, 80MW, VT900 Series.