This circuit based project can be used to understand working of a differential amplifier circuit. A d**ifferential amplifier circuit **is an amplifier circuit which amplifies the voltage difference between two inputs. This amplification takes place according to the formula

V_{out}=[{(R_{f }+ R_{1})R_{g }}/{(R_{g}+R_{2})R_{1}}]V_{2 }-(R_{f}/R_{1})V_{1}

If all resistances are equal then differential gain becomes unity and Vout becomes V_{2}-V_{1}:

V_{out}= V_{2 }-V_{1}