Here is an

**Operational amplifier based sine wave generator circuit**, it is basically a

**wein bridge oscillator**. Because of its simplicity and stability, one of the most commonly used audio frequency oscillator is wein-bridge. The wein bridge oscillator in which the weinbridge circuit is connected between the amplifier input and output terminals. The bridge has a series RC network in one arm and a parallel RC network in the adjoining arm. in the remaining arms of bridge, input resistor R1 and Feedback Resistor Rf is connected.

### CIRCUIT DIAGRAM

### COMPONENTS REQUIRED

Components | Rating | Quantity |

OP AMP | 741/351 | 1 |

Resistors | 12K | 1 |

3.3K | 2 | |

Pot | 24K | 1 |

Capacitors | 0.05uF | 2 |

Dual Voltage Power Supply | +/- 15V | 1 |

The phase angle criterion for oscillation is that the total phase shift around the circuit must be 0o. This condition occurs only when the bridge is balanced, that is, at Resonance. The frequency of oscillation F0 is exactly the resonant frequency of the balanced wein bridge and is given by:-

F0 = 1/(2"RC) = 0.159/RC

The resistors and capacitors in the reactive leg of wein bridge is same. At this frequency the gain required for sustained oscillation is given by:-

AV = 1/B = 3

It would be better 2 mention the cost of ckts;-)

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