Figure 7 and Figure 8 is the circuit of the Wien bridge oscillator A resistor R4 is connected to the inverting terminal (2) of the operational amplifier from the ground Similarly a parallel combination of a resistance R2 and a capacitor C2 is connected to the non-inverting terminal (3) of the operational amplifier from the ground The output terminal (6) of the amplifier is fed back to inverting terminal (2) through a resistor R3 A series combination of a resistance R1 and a capacitor C1 is connected between non-inverting terminal (3) and the output of operational amplifier To observe the output wave form the output terminal (6) is connected to oscilloscope The terminals (7) and (4) of the op-amp are connected to +12v and -12v of the DC power supplies separately