Wien bridge oscillator multisim

ELEC 161 – Module 7 Laboratory - Page 1

ELEC 161 Electronics II Module 7 Lab: Analog Oscillators

Introduction.- In the previous lab we explored oscillator circuits that produce a square signal that can be used as a clock signal. In this laboratory experience, we will explore different circuits that can be used to generate an analog signal, typically a sine signal.

Procedure

1.- The Op-Amp based Phase Shift Oscillator

1.1 Build the circuit shown in Figure 7-1.

Figure 7- 1: Phase-shift oscillator

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1.2 Connect the Oscilloscope at Vout and run the simulation. If the circuit does not start oscillating within a few seconds, slightly change the value of the potentiometer until it starts oscillating. In real circuits, the electrical noise inherent to all circuits triggers the circuit to oscillate. In Multisim, we simulate this noise by the change in current created by changing the value of the potentiometer.

1.3 After the oscillation starts, modify the value of the potentiometer so there is no clipping in the output signal.

1.4 Measure the frequency of the output signal. Don’t forget to include screenshots as necessary.

1.5 Calculate the theoretical oscillation frequency using the formula form your textbook.

1.6 Modify the circuit to obtain an oscillation frequency of approximately 1500 kHz. Include screenshots of the circuit and oscilloscope.

2. Wien Bridge Oscillator

2.1 Build the circuit shown in Figure 7-2.

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Figure 7- 2: Wien Bridge Oscillator

2.2 Connect the Oscilloscope at Vout and run the simulation

2.4 Measure the frequency of the output signal. Don’t forget to include screenshots as necessary.

2.5 Calculate the theoretical oscillation frequency using the formula form your textbook.

2.6 Modify the circuit to obtain an oscillation frequency of approximately 1500 kHz. Include screenshots of the circuit and oscilloscope.

Laboratory Report Create a laboratory report using Word or another word processing software that contains at least these elements:

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- Introduction: what is the purpose of this laboratory experiment?

- Results for each section : Measured and calculated values, calculations, etc. following the outline. Include screenshots for the circuits and waveforms as necessary -- You can press Alt + Print_Screen inside Multisim or if using Windows 7, you can use the “Snipping tool”. Either way, you can paste these figures into your Word processor. Also include here the charts and graphs that you have created with the data you have collected.

- Conclusion : What area(s) you had difficulties with in the lab; what did you lean in this experiment; how it applies to your coursework and any other comments.