The Input Impedance of this module is very high and is
symmetric. This circuit can be used for strain gauges and for four wire
measurements. If inputs are in mV use OP07. The merit is that it uses
only 2 OpAmps yet has high differential Input Impedance.
Get Dual Differential Amp Tutorial
The Variable Resistor or Sliding Potentiometer for Rf and Ri are present for Gain Setting. Slide them to vary Rf and Ri, Assume both Rf values vary in tandem, when you slide the Rf Pot. Like a Ganged Pot or Dual Pot. Even Ri is a Dual Pot that varies both Ri Simultaneously. Now set the mV of Vp and Vn using the mV Sources provided. Just Hover Mouse pointer over buttons, variation ramps up if mouse pointer is left on the buttons. No pressing Buttons here. Take the Vout readings, tabulate the Results.
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