RC Phase Shift Oscillator & Wien Bridge Oscillator
Experiment 4
Aim:
To Design and construct Wien Bridge Oscillator & RC Phase Shift Oscillator Circuit using IC 741 and observe its output waveforms
Apparatus Required:
Theory:
RC Phase Shift Oscillator: A phase shift oscillator is a simple sine wave electronic oscillator. It contains an inverting amplifier, and a feedback filter, which 'shifts' the phase by 180 degrees at the oscillation frequency. The filter must be designed so that at frequencies above and below the oscillation frequency, either more or less than 180 degrees shifts the signal. This results in constructive superposition for signals at the oscillation frequencies, and destructive superposition for all other frequencies. The mathematics for calculating the oscillation frequency and oscillation criteria for this circuit are surprisingly complex, due to each R-C stage loading the previous ones. The calculations are greatly simplified by setting all the resistors (except the negative feedback resistor) and all the capacitors to
Wien Bridge Oscillator: A Wien bridge oscillator is a type of electronic oscillator that generates sine waves without having any input source. It can output a large range of frequencies. The bridge comprises four resistors and two capacitors. The circuit is based on a network originally developed by Max Wien in 1891.In Wien bridge oscillator, wien bridge circuit is connected between the amplifier input terminals and output terminals. The bridge has a series RC network in one arm and parallel network in the adjoining arm. In the remaining 2 arms of the bridge resistors R1and Rf are connected. To maintain oscillations total phase shift around the circuit must be zero and loop gain unity. First condition occurs only when the bridge is balanced. Assuming that the resistors and capacitors are equal in value, the resonant frequency of balanced bridge is given by / the frequency of oscillation is given by:
Design
Circuit Diagram
Observations
Procedure
Construct the circuit as per Circuit diagram shown in figure.
Switch On the equipment and observe the Output waveform on CRO.
Note the readings and verify its frequency with theoretical frequency.
Draw the waveform on Graph Sheet.
Link to experiment
Go here and select Experiment 4
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