The Instrumental Amplifier is considerably an input impedence matching eliminator, thus being considered as a type of input buffer amplifier. Due to this fact, this instrument is very often in test equipment.
Output Voltage of this Instrumentation amplifier is found as follows:
Vo=(R4/R5) *(1+(2R)/Rg)*(V2-V1)
Where R=R1=R2 and R4=R6 and R3=R5.
Rg is the resistance in between R1 and R2 to which differential gain is found as (V2-V1). R4 is the feedback resistance of Op-Amp 3. R6 is the resistance connected directly from non-inverting pin of Op-Amp 3 to ground.
Testing (theoretical):
1) V1= 1V, V2= 2V then Vo= 10V
2) V1= -1V, V2= -2V then Vo= -10V
3) V1= 1V, V2= -0.3V then Vo= -13V
4) V1= - 1V, V2= 0.3V then Vo= 13V
This experiment has been tested practically in a Lab, and accurate practical readings have been found similar to this.
