Measuring the output of strain gauges
In this video I show you what are the challenges of measuring the tiny changes in the resistance of a strain gauge. The resistance of an unloaded strain gauge is around 350 Ohm (at least the one I use in this video) and a loaded one's is 1-2 Ohms smaller or larger. This is a small change, it is difficult to measure it and it is even more difficult when it is a change in the resistance of something. To make this value into a more comprehensive one, I use a Wheatstone bridge to convert the change in the resistance into a change in voltage. The obtained voltage change is still tiny (few tens of microvolts), therefore I use the built-in PGA (Programmable Gain Amplifier) of an ADS1256 AD converter to resolve this tiny change.
Schematics
A simple sketch of the circuit I was using in the demonstration. One of the 350R resistors (upper right) in the Wheatstone bridge is replaced by a strain gauge. The potmeter allows you to adjust the input voltage of the Wheatstone bridge. The input voltage of the regulator is 12 V. The capacitors are 10 uF capacitors. The output voltage of the Wheatstone bridge is used for further analysis.
