Hello Jigar,

Namaste and Greetings!

The data loggers usually have input range or +/-5V, +/-10V etc.or even some times down to +/-2.5V. The signals from the strain gauges are in the typical range of +/-20mV.

A simple instrumentation amplifier for the gauges should solve your problem. Just check also the excitation for the strain gauges. Almost all data logger do not have power supply output or even if available, will be at limited currents. SO you will have to have a separate power supply for the excitation.

Hope this solves your problem. Please do let me know if my solution has helped you or not?

Wish you all the best!

Refer Tech notes of Micro Measurements which gives guide lines . Always note if you are Looking for low frequency or almost static stress analysis use AC excitation. Else DC excitation is better

Refer Tech notes on System 5000 Data Acquisition System of Micro Measuremnts a Vishay Precision Group subsdiary. They have real good solutions

Mandar,

I suggested a solution to be used with a compact, low cost USB based data acquisition systems. This should be a starting point to get the feel as how the system is working and what sort of behavioral data we can expect.

Sophisticated systems such as you suggested will always come at a later stage.

Let's hear from Jigar as what are the developments at his end.

Yes Mr Jigar. I always used simple Instrumentation amplifier with standard low cost 5 V DC supply for excitation. One should note in order to avoid unbalance a balanced Wheatstone's Bridge formation must be used. The outputs are in mV and hence need use stable output multimeter, typical of standard company such as of Agilent, Tektronix or Fluke.

Mandar,

I think it is better to excite the bridge (strain-gauges) with a dual polarity supply such as +/-5 VDC. As I have stated above, the output is +/- 2mV or +/-20mV depending upon your selection. Then it becomes pretty straight forward to use either a differential amplifier (using one op-amp would also work) or use the classic three op-amp instrumentation amplifier. You need to have some OFFSET adujstments and a low-pass filter at the output typically designed for

This is good and would probably have very low offset

but amplifier with High Input Impedance having high CMRR are essential to decipher the very low amplitude stress signal and then amplify. Hence Instrumentation amplifiers are preferred suitable for job . use AD 520/522/524/ either of these

thanks for reply