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Differential Amplifier Doubt

rdevendrakumar1989

Aug 9, 2012
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Hai friends,

Am design a circuit to measure resistance value interms of voltage by using differential amplifier... Am use voltage follower for each input.. But differential amplifier output comes only 70%. am also nullify the offset voltage.. Whats the reason for that.. Give me solution as soon as possible pls
 

Harald Kapp

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Give us a schematic as soon as possible pls.
 

rdevendrakumar1989

Aug 9, 2012
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03045.png



v1 and v2 are the 2 ends or resistor
 

Harald Kapp

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In principle the circuit should work. What are the voltages (supply, V1, V2, Vout)? What type of OpAmp are you using?
Are you sure the difference voltage at Vout is within the operational range of the OpAmps?

Also: The OpAmp has a (admittedly very) small input current.You need to provide a path to ground for this current. See this application note.
 
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