Wien bridge oscillator is an audio frequency sine wave oscillator of high stability and simplicity. An oscillator is a circuit that produces periodic electric signals such as sine waves or square waves. The application of oscillators includes sine wave generators, local oscillators for synchronous receivers, etc.

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. Wien bridge circuit is simply a series RC network in one arm and a parallel RC network in the adjoining arm. Resistors Ri and Rf are connected in the remaining two arms.

## Wien Bridge Oscillator Circuit Diagram

## Components Required

- Resistors (1KΩ, 1.5KΩ x2)
- Potentiometer(4.7KΩ)
- Capacitor(0.1µF x2)
- 741 Op amp

## Output Waveform

## Working of Wein bridge Oscillator

- The feedback signal in this oscillator circuit connects the non-inverting input terminal so that the op-amp works as a non-inverting amplifier.
- The condition of zero phase shift around the circuit is achieved by balancing the bridge, zero phase shift is essential for sustained oscillations.
- The frequency of oscillation is the resonant frequency of the balanced bridge and the expression is fo = 1/2πRC
- At resonant frequency ( ƒo), the inverting and non-inverting input voltages is equal and “in-phase” so that the negative feedback signal will cancell out by the positive feedback causing the circuit to oscillate.
- From the analysis of the circuit, it is clear that the feedback factor β= 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.
- For an inverting amplifier the gain is set by the feedback resistor network Rf and Ri and is given as the ratio -Rf/Ri.

## Conclusion

Wein bridge oscillator is one of the most common circuits in electronics projects. To deal with a different kind of frequency wave, this is a must. By following the above tutorial, constructing a wein bridge oscillator will not be a big problem at all in the future.

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