User Manual

Rev E Aug 2022
Page 1
Chapter 1 Overview
Chapter 1 Overview
This pre-amplification circuitry is designed to amplify resistance changes within a full Wheatstone bridge strain gauge, to produce
a signal suitable for monitoring and interpretation by the Thorlabs strain gauge reader or other piezo electronics with feedback.
This circuit can also be used in other custom applications.
The amplification circuitry uses a low power, general purpose instrumentation amplifier offering excellent accuracy suitable for
strain gauge bridge amplification. Current-feedback input circuitry provides wide bandwidth even at high gain (200kHz at G = 100).
A single external resistor sets any gain from 1 to 10,000. The INA128 amplifier component provides an industry standard gain
equation.
Under normal operating conditions the Thorlabs strain gauge reader anticipates a voltage range of >0v to 2V Pk-Pk for minimum
and maximum strain.
Note: There is no phase monitoring to determine bridge polarity. The bridge should only be used for positive strain, where the
bridge does not cross the balance point during operation.