PHYS245 Electricity and Electronics Syllabus - Classes - Assignments - Laboratory - Resources Class 34: Review of Amplifiers, etc.

Review of Special Problem 8.1

The examination of the Wheatstone bridge reviews simple circuit analysis concepts, the examination of the capacitive coupling reviews simple filter concepts, and the examination of the amplifier reviews simple amplifier concepts in preparation for the next quiz on amplifiers.

A motor with an eccentric load is turning at 1200 rpm. A strain gauge is used to monitor the vibration in the motor mounting. The Wheatstone bridge and amplifier produce an output voltage proportional to the strain in the mounting. The capacitor blocks the dc component from the bridge, ac-coupling the amplifier.

1. Assuming that the strain gauge resistance, R_sg, is nominally 1k, find the value of the capacitance that will set the characteristic frequency of the coupling to one-third of the frequency of vibration.

2. Choose A_v so that a 1.0% change in the strain gauge resistance produces a 5 V change in the output of the amplifier.

This problem is from Roadstrum and Wolaver Ch. 8, Problem 9.