Wien bridge oscillator is an audio frequency sine wave oscillator of high stability and simplicity. Before that let us see what is oscillator An oscillator is a circuit that produces periodic electric signals such as sine wave or square wave. The application of oscillator includes sine wave generator, local oscillator for synchronous receivers et
c. Here we are discussing wein bridge oscillator using 741 op amp IC. It is a low frequency oscillator. The op-amp used in this oscillator circuit is working as non-inverting amplifier mode. Here the feedback network need not provide any phase shift. The circuit can be viewed as a wien bridge with a series RC network in one arm and parallel RC network in the adjoining arm. Resistors Ri and Rf are connected in the remaining two arms. At resonant frequency ( ’o), the inverting and non-inverting input voltages will be equal and in-phase so that the negative feedback signal will be cancelled out by the positive feedback causing the circuit to oscillate. From the analysis of the circuit, it can be seen that the feedback factor ²= 1/3 at the frequency of oscillation. Therefore for sustained oscillation, the amplifier must have a gain of 3 so that the loop gain becomes unity.