What had to be solved
The task was to make a specialized analog module for static and dynamic strain-gauge measurements where bandwidth, stable setup and compatibility with different bridge configurations are important.
Projects / Measurements, sensors and data acquisition
500 kHz strain-gauge bridge amplifier
High-frequency amplifier for Wheatstone bridges: bridge excitation, amplification of small differential strain-gauge signals, hardware setup and analog outputs for test systems.
What the project reached
A compact measurement module was developed for laboratory and test-bench use. The board powers the bridge, amplifies the small signal and sends a conditioned analog output to the recording system.
Project materials
Photos and working materials
Engineering context
Important constraints
The device works with small signals from strain resistors.
It supports full-bridge, half-bridge with dummy gauge and quarter-bridge configurations.
The measurement path bandwidth is up to 500 kHz.
The output signals are intended for external recording and test equipment.
Work done
What was included
Analog path based on an instrumentation amplifier and high-speed operational amplifiers.
Bridge and board power from laboratory supplies.
On-board switching of bridge configurations.
Hardware adjustment of gain, bridge supply and balance.
PCB layout with attention to wideband analog signals.
Details
Engineering project description
Purpose
The device is intended to power a Wheatstone bridge, amplify small differential signals from strain gauges and pass the conditioned analog signal to measurement or test equipment.
Modes and parameters
- full bridge, half bridge with dummy gauge and quarter bridge
- bandwidth up to 500 kHz
- +/-10 V output signal and a separate 0...10 V output
- hardware gain switching x1000 / x2000
- bridge-supply and balance adjustment
Technical implementation
The analog path is built around an AD8421 instrumentation amplifier and LM7171 high-speed operational amplifiers. The board is intended for laboratory and bench applications where wide bandwidth and stable hardware adjustment before an experiment are important.
Contact
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