DESIGN OF EXPERIMENT

RC PHASE SHIFT OSCILLATOR

Course: Section:

Group Number: Date Performed:

Name: Date Submitted:

Instructor:

1. Objective(s):
1. Apply knowledge in multisim to understand RC phase-shift oscillator
2. Identify, formulate, and gather data using multisim
3. Use techniques, skills, and multisim for engineering practices.
4. Show the graphically waveform produced by RC phase-shift oscillator
2. Intended Learning Outcomes (ILOs):
The students shall be able to:
2.1 Know the uniqueness of RC phase-shift oscillator from the other types of oscillator
circuits.
2.2 Grasp the idea on how the RC phase-shift oscillator works through the oscilloscope using
multisim.
2.3 Understand how the Resistors affects the oscillation.
2.4 Understand how the Capacitors affects the oscillation.
3. Discussion:

Simple Rc oscillators are commonly used in audio frequency applications that span the frequency range
from several hertz to several tens kilohertz. The two most commonly used oscillator circuits are the RC
phase-shift and Wien-bridge oscillators.

The phase-shift is one of the simplest oscillators to design and construct in the audio frequency range.
The oscillator exemplifies the simple principles and conditions of oscillation. A simple OpAmp-based
phase-shift oscillator is shown in the Figure 1.

Figure 3..1 : OpAmp-based phase-shift oscillator

The purpose of this simulation is to demonstrate the characteristics and operation of a phase shift
oscillator. Figure 3.1 uses a third order high-pass RC network feedback loop for its particular oscillator
circuit design. As in this case with all the oscillators, the barkhausen criteria specifying a required 360
degree phase shift from input to output and a total gain of one must be adhered to in the design of a
phase shift oscillator. In the figure, the inverting op amp provides a phase shift of 180 degrees. The RC
network must provide an additional 180 degrees for a total phase shift of zero degrees. Each section
provides an additional 180 degrees for a total phase shift of zero degrees. Each section provides
approximately 60 degrees of this requirement. The filter portion consisting of the RC network introduces
an attenuation that the op-amp must match in gain in order to achieve an overall gain of one.

The minimum gain required of the op-amp so that it sustains oscillations is 29. Keeping the gain as close
to 29 as possible will prevent the peaks of the waveform from being driven into the non-linear region.
This will minimize clipping of the sinusoidal input.

Formula:

Frequency of oscillation:

1
𝑓𝑐 =
2𝜋𝑅𝐶√6

In order to sustain

𝑅𝑓
= 29
𝑅

4. Resources

 Multisim

Test Equipment
 Oscilloscope
 Spectrum Analyzer

Parts
 DC supply
 Opamp: 741-DiV
 Resistors: 10k(3), 1M potentiometer
 Capacitor 10nf(3)
5. Procedure

RC PHASE SHIFT OSCILLATOR

1. Open multisim
2. Construct the circuit in figure 5.1

Figure 5.1

3. Double click the oscilloscope to view its display. Set the time base to 2ms/div, Channel A to
2v/Div and Channel B to 200mV/Div

Figure 5.2

4. Select and Simulate/Interactive Simulation settings, and select Set to zero for initial conditions
5. Start the simulation and place a spectrum Analyzer on the workspace and connect its input to
the output lead of the oscillator.
6. Double click to open the spectrum analyzer window.
7. Press set span. Set start = 0khz, End = 1khz, Amplitude = LIN and Range = 2v/div. click enter
 Figure 5.3

8. Restart the simulation. When the oscillator has stabilized, drag the red marker to the position of
the spectrum line observed. Note the frequency in the lower left corner of the spectrum analyzer
window.

F = _______________

9. Adjust the potentiometer to the point where oscillation begins. Measure the value of the
potentiometer resistance at this point and complete the table below
10. Open the oscilloscope window. Measure and note the phase shift at the oscilloscope inputs

Measured Value Calculated Value %Error

Frequency (Hz)
Rf/R at the point where
oscillation begins

Table 5.1
Draw the waveform

Figure 5.4
 11. For the circuit in figure 5.1 replace the existing simulated capacitor value to 1nf and 100nf.
12. Repeat the same procedure
13. Run the simulation and compare the output data with expected theoretical values.

1nf

Measured Value Calculated Value %Error

Frequency (Hz)
Rf/R at the point where
oscillation begins
Table 5.2

Draw the waveform

Figure 5.5

100nf

Measured Value Calculated Value %Error

Frequency (Hz)
Rf/R at the point where
oscillation begins
Table 5.3
Draw the waveform

Figure 5.6
6.Data and Results.

7. Observation

8. Interpretation

9.Question and Problem

1. Why are RC oscillators incapable of generating high frequency oscillations?

_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
 _____________________________________________________________

2. What are the applications of RC phase shift oscillators? Can you give a short explanation on
how that application works?
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________

3. At what phase shift does RC phase shift oscillator produce? 4 Why do we need a phase shift
between an input and output signal?
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________

4. How can we get a maximum phase angle of 90 degrees in RC phase shift oscillator?
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________

Conclusion
 DESIGN OF EXPERIMENT
RC PHASE SHIFT OSCILLATOR
Course: ECE402 Section:

Group Number: Date Performed:

Name: Date Submitted:

Instructor:

1. Objective(s):
5. Apply knowledge in multisim to understand RC phase-shift oscillator
6. Identify, formulate, and gather data using multisim
7. Use techniques, skills, and multisim for engineering practices.
8. Show the graphically waveform produced by RC phase-shift oscillator
3. Intended Learning Outcomes (ILOs):
The students shall be able to:
2.1 Know the uniqueness of RC phase-shift oscillator from the other types of oscillator
circuits.
2.2 Grasp the idea on how the RC phase-shift oscillator works through the oscilloscope using
multisim.
2.3 Understand how the Resistors affects the oscillation.
2.4 Understand how the Capacitors affects the oscillation.
6. Discussion:

Simple Rc oscillators are commonly used in audio frequency applications that span the frequency range
from several hertz to several tens kilohertz. The two most commonly used oscillator circuits are the RC
phase-shift and Wien-bridge oscillators.

The phase-shift is one of the simplest oscillators to design and construct in the audio frequency range.
The oscillator exemplifies the simple principles and conditions of oscillation. A simple OpAmp-based
phase-shift oscillator is shown in the Figure 1.

Figure 3..1 : OpAmp-based phase-shift oscillator

The purpose of this simulation is to demonstrate the characteristics and operation of a phase shift
oscillator. Figure 3.1 uses a third order high-pass RC network feedback loop for its particular oscillator
circuit design. As in this case with all the oscillators, the barkhausen criteria specifying a required 360
degree phase shift from input to output and a total gain of one must be adhered to in the design of a
phase shift oscillator. In the figure, the inverting op amp provides a phase shift of 180 degrees. The RC
network must provide an additional 180 degrees for a total phase shift of zero degrees. Each section
provides an additional 180 degrees for a total phase shift of zero degrees. Each section provides
approximately 60 degrees of this requirement. The filter portion consisting of the RC network introduces
an attenuation that the op-amp must match in gain in order to achieve an overall gain of one.

The minimum gain required of the op-amp so that it sustains oscillations is 29. Keeping the gain as close
to 29 as possible will prevent the peaks of the waveform from being driven into the non-linear region.
This will minimize clipping of the sinusoidal input.

Formula:

Frequency of oscillation:

1
𝑓𝑐 =
2𝜋𝑅𝐶√6

In order to sustain

𝑅𝑓
= 29
𝑅

7. Resources

 Multisim

Test Equipment
 Oscilloscope
 Spectrum Analyzer

Parts
 DC supply
 Opamp: 741-DiV
 Resistors: 10k(3), 1M potentiometer
 Capacitor 10nf(3)

8. Procedure

RC PHASE SHIFT OSCILLATOR

14. Open multisim
15. Construct the circuit in figure 5.1

Figure 5.1

16. Double click the oscilloscope to view its display. Set the time base to 2ms/div, Channel A to
2v/Div and Channel B to 200mV/Div

Figure 5.2

17. Select and Simulate/Interactive Simulation settings, and select Set to zero for initial conditions
18. Start the simulation and place a spectrum Analyzer on the workspace and connect its input to
the output lead of the oscillator.
19. Double click to open the spectrum analyzer window.
20. Press set span. Set start = 0khz, End = 1khz, Amplitude = LIN and Range = 2v/div. click enter
 Figure 5.3

21. Restart the simulation. When the oscillator has stabilized, drag the red marker to the position of
the spectrum line observed. Note the frequency in the lower left corner of the spectrum analyzer
window.

F = 343.63 Hz

22. Adjust the potentiometer to the point where oscillation begins. Measure the value of the
potentiometer resistance at this point and complete the table below
23. Open the oscilloscope window. Measure and note the phase shift at the oscilloscope inputs

Measured Value Calculated Value %Error

Frequency (Hz) 343.63 324.887 5.46%
Rf/R at the point where 700k ohm 700k ohm 0%
oscillation begins

Table 5.1
Draw the waveform

Figure 5.4
 24. For the circuit in figure 5.1 replace the existing simulated capacitor value to 1nf and 100nf.
25. Repeat the same procedure
26. Run the simulation and compare the output data with expected theoretical values.

1uf

Measured Value Calculated Value %Error

Frequency (Hz) 4.132hz 4.11 hz .5%
Rf/R at the point where 650k ohms 650k ohms 0%
oscillation begins
Table 5.2
Draw the waveform

Figure 5.5

100nf
Measured Value Calculated Value %Error
Frequency (Hz) 53.719 55.555 3.41%
Rf/R at the point where 450k ohms 450k ohms 0%
oscillation begins
Table 5.3
Draw the waveform
 Figure 5.6
6.Data and Results.

Calculated values:
@10nf
Frequency:
1
𝑓= = 𝟑𝟐𝟒. 𝟖𝟖𝟕𝒉𝒛
3.08

Percent error
324.887 − 343.324
| | 𝑥100 = 𝟓. 𝟒𝟔%
343.324

@1uf
Frequency:
1
𝑓= = 𝟒. 𝟏𝟏𝒉𝒛
242.01

Percent error
4.11 − 4.13
| | 𝑥100 =. 𝟓%
4.11

@1nf
Frequency:
1
𝑓= = 𝟓𝟓. 𝟓𝟓𝒉𝒛
18𝑚𝑠

Percent error
55.55 − 53.719
| | 𝑥100 = 𝟑. 𝟒𝟏%
53.719
7. Observation

For the experiment, we constructed an RC Phase-Shift circuit. It mainly focuses on the resistor and
capacitors that are basically a Reactive Phase-Shift Network. The simulation of the circuit gave us a
measured value of 343.63 Hz as frequency and the point where oscillation begins at 700k ohm. Using
the formula provided, we calculated the value of the frequency at 324.887 Hz and the oscillation point at
700k ohm. This gave us a percentage difference at 5.46 % and 0%. The waveform this made started
small, gaining traction until it stabilized at 700k ohm.
For the remainder of the experiment, we repeated the simulation but replaced the value of the capacitors
to 1nF and 100nF. With the new capacitors, percentage error we got for the frequencies were 0.5% and
3.41% and the oscillation point remained at 0% for both.

8. Interpretation

The experiment demonstrated the characteristics and operation of a phase shift oscillator. It produced a
leading phase shift or interchanged to produce a lagging phase shift that has an outcome that is still the
same as the sine wave oscillations which only occurs at the frequency at which the overall phase-shift is
360 degrees.
One of the most important features of an RC oscillator is its frequency stability which is its ability to
provide a constant frequency sine wave output under varying load conditions. This feature is noticeable
in the data collected during the experiment. The output frequency is proportional to 1/RC.

9.Question and Problem

1. Why are RC oscillators incapable of generating high frequency oscillations?

- At high frequencies, resistors look like inductors or capacitors so the equations that govern
oscillation in RC oscillators no longer apply. In other words, because of those parasitic
components, it gets more and more difficult to make a stable RC oscillator as frequencies
go up. At some point it becomes easier and more stable to use other types of oscillators .

2. What are the applications of RC phase shift oscillators? Can you give a short explanation on
how that application works?

- RC phase shift oscillators are mostly used at audio frequencies. Other than this, electronic
organs makes use of this oscillator such as electronic musical instruments like pianos. Also
used in equipment that emits beeps. Example, many GPS units beeps when they performs
an action. Also used in voice synthesis.
 3. At what phase shift does RC phase shift oscillator produce? 4 Why do we need a phase shift
between an input and output signal?

- RC phase shift oscillator produces a phase shift of 180 degrees between output and input
signal. In the phase-shift oscillator, at least three RC sections are needed to give the
required 180-degree phase shift for regenerative feedback. The values of resistance and
capacitance are generally chosen so that each section provides about a 60-degree phase
shift. To obtain the regenerative feedback in the phase-shift oscillator, we need a phase
shift of 180 degrees between the output and the input signal. An RC network consists of
three RC sections which provides the proper feedback and phase inversion to provide this
regenerative feedback. Each section shifts the feedback signal 60 degrees in phase.

4. How can we get a maximum phase angle of 90 degrees in RC phase shift oscillator?

- By changing the resistance to zero, we can get a maximum phase angle of 90 degrees. But
since we cannot develop voltage across zero resistance, so a 90 degree phase shift is not
possible.

Conclusion

By effectively following through the procedures of the experiment, we safely applied the knowledge in
Multisim to understand RC phase-shift oscillator. With Multisim we were able to produce a graphical
waveform of the RC phase-shift oscillator.
The data we gathered was accurate to within less than 6% with the oscillation point being at a consistent
0%. This means that the measured values we got for the experiment was not far off from the calculated
or true value of the circuit. It produced a leading phase shift or interchanged to produce a lagging phase
shift that has an outcome that is still the same as the sine wave oscillations which only occurs at the
frequency at which the overall phase-shift is 360 degrees.
One of the most important features of an RC oscillator is its frequency stability which is its ability to
provide a constant frequency sine wave output under varying load conditions. This feature is noticeable
in the data collected during the experiment. The output frequency is proportional to 1/RC.
 TECHNOLOGICAL INSTITUTE OF THE PHILIPPINES
RUBRIC FOR ENGINEERING KNOWLEDGE
(Engineering Programs)

Student Outcome (a): Apply knowledge of mathematics, science, and engineering to solve complex engineering problems.

Program: Course: _______________ Section: Semester School Year ____________

Unsatisfactory Satisfactory Exemplary

Performance Indicators Score
1 2 3
1. Choose the appropriate mathematical, The student does not know any The student can identify but fails to The student correctly applies an
science, and engineering principles in mathematical, science, and apply an appropriate mathematical, appropriate mathematical,
solving problems in engineering. engineering principle that can be science, and engineering principle to science, and engineering principle
used to solve a given engineering solve an engineering problem. to solve an engineering problem.
problem.

2. Examine different approaches in The student uses a wrong approach The student can solve the problem The student is able to solve the
solving problems in engineering and in solving problems in engineering. using a single approach. problem correctly using multiple
choose the most effective approach. approaches.

3. Apply the appropriate mathematical, The student cannot solve a given The student applies mathematical, The student applies the correct
science, and engineering principles to engineering problem. science, and engineering principle mathematical, science, and
arrive at a solution but does not arrive at the correct engineering principle to solve the
answer. problem and arrives at the correct
answer.

Total Score
Mean Score = (Total Score / 3)
Percentage Rating = (Total Score / 9) x 100%
Evaluated by:

Printed Name and Signature of Faculty Member Date

 TECHNOLOGICAL INSTITUTE OF THE PHILIPPINES
RUBRIC FOR ENGINEERING PROJECTS
(Engineering Programs)

Student Outcome (b): Identify, formulate and solve complex engineering problems.

Program: Course: _______________ Section: Semester School Year

____________

Unsatisfactory Satisfactory Exemplary

Performance Indicators Score
1 2 3
4. Ability to identify an engineering The problem is not identified The problem is stated but not The statement of the problem
problem clearly identified has been clearly and fully
(Statement of the Problem) identified.
5. Ability to formulate engineering Unable to formulate an Presents a general approach to Presents a detailed step by step
solutions to a given problem appropriate solution to the solve an engineering problem solution to solve an engineering
(Design/Research Methodology) problem problem
6. Ability to apply the best solution Not able to solve the given The solution to the problem The correct solution to the
to an engineering problem engineering problem has not been fully elaborated problem has been clearly
(Summary and Conclusion) derived and presented

Total Score
Mean Score = (Total Score / 3)
Percentage Rating = (Total Score / 9) x 100%

Evaluated by:

Printed Name and Signature of Faculty Member Date

 TECHNOLOGICAL INSTITUTE OF THE PHILIPPINES

RUBRIC FOR CONDUCT OF EXPERIMENTS

(Engineering Programs)

Student Outcome (d1): Design and conduct experiments, as well as to analyze, and interpret data, and synthesize information to provide valid conclusions for
investigating complex problems.

Program: Course: _______________ Section: Semester School Year ____________

Group Members:

Beginner Acceptable Proficient

Performance Indicators 1 2 3 Score
1. Conduct experiments in accordance with Members do not follow good Members follow good and safe Members follow good and safe
good and safe laboratory practice. and safe laboratory practice in laboratory practice most of the laboratory practice at all times in
the conduct of experiments. time in the conduct of the conduct of experiments.
experiments.
2. Operate equipment and instruments with Members are unable to operate Members are able to operate Members are able to operate the
ease the equipment and instruments. equipment and instrument with equipment and instruments with
supervision. ease and with minimum
supervision.
3. Analyze data, validate experimental values The group has incomplete data. The group has complete data but The group has complete data,
against theoretical values to determine has no analysis and valid validates experimental values
possible experimental errors, and provide conclusion. against theoretical values, and
valid conclusions. provides valid conclusion.
Total Score
Mean Score = (Total Score / 3)
Percentage Score = (Total Score / 9) x 100%
Evaluated by:

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 TECHNOLOGICAL INSTITUTE OF THE PHILIPPINES

RUBRIC FOR FINAL LABORATORY PROJECT

(Engineering Programs)

Student Outcome (d2): Design and conduct experiments, as well as to analyze, and interpret data, and synthesize information to provide valid conclusions for
investigating complex problems.

Program: Course: _______________ Section: Semester School Year _____________

Group Members:

Beginner Acceptable Proficient

Performance Indicators 1 2 3 Score
1. Identify the procedures involved in designing Fails to design an experiment Designs an experiment Designs an experiment exceeding
an experiment following given procedures. satisfying the minimum the requirements of the
requirements of the procedures. procedures.

2. Develop a protocol to conduct an experiment Fails to develop a protocol to Develops a protocol to conduct Develops a protocol to conduct an
conduct an experiment. an experiment satisfying experiment exceeding the
minimum requirements. requirements.

Total Score
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Evaluated by:

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 RUBRIC FOR MODERN TOOL USAGE
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Program: Course: _______________ Section: Semester School Year ____________

Unsatisfactory Developing Satisfactory Very Satisfactory

Performance Indicators 1 2 3 4 Score

7. Apply appropriate Fails to identify any modern Identifies modern techniques Identifies modern techniques Applies the most appropriate
techniques, skills, and techniques to perform but fails to apply these in and is able to apply these in modern technique in performing
modern tools to perform a discipline-specific performing discipline-specific performing discipline-specific discipline-specific engineering
discipline-specific engineering task. engineering task. engineering task. task exceeding the requirements.
engineering task.
8. Demonstrate skills in Fails to apply any modern Attempts to apply modern tools Shows ability to apply Shows ability to apply the most
applying different techniques tools to solve engineering but has difficulties to solve fundamental procedures in appropriate and effective modern
and modern tools to solve problems. engineering problems. using modern tools when tools to solve engineering
engineering problems. solving engineering problems. problems.
9. Recognize the benefits and Does not recognize the Recognizes some benefits and Recognizes the benefits and Recognizes the need for benefits
constraints of modern benefits and constraints of constraints of modern constraints of modern and constraints of modern
engineering tools. modern engineering tools. engineering tools. engineering tools and shows engineering tools and makes good
intention to apply them for use of them for engineering
engineering practice. practice.
Total Score

Mean Score = (Total Score / 3)

Percentage Rating = (Total Score / 12) x 100%

Evaluated by:

Printed Name and Signature of Faculty Member Date

 TECHNOLOGICAL INSTITUTE OF THE PHILIPPINES

RUBRIC FOR PROJECT MANAGEMENT

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Student Outcome (k): Demonstrate knowledge and understanding of engineering and management principles and apply these to one’s own work, as a
member and leader in a team, to manage projects and in multidisciplinary environments.
Program: Course: _______________ Section: Semester School Year ____________
Performance Indicators Unsatisfactory Satisfactory Exemplary
1 2 3 Score
1. Understands engineering and Team members do not Team members demonstrate some Team members are knowledgeable
management principles demonstrate awareness of any knowledge of engineering and about engineering and management
engineering and management management principles principles
principles
2. Applies engineering and Team members do not Team members accept a designated Team members accepted and executed
management principles to an demonstrate willingness to role in an assigned task and in with full competence a designated role in
assume a designated role in a multidisciplinary environments but the an assigned task and in multidisciplinary
assigned task and in multidisciplinary environments beyond the expected output
environments group project expected output was not fully
completed
3. Manages assigned projects in Project does not meet minimum Project meets the minimum Project exceeds the minimum
multidisciplinary environments requirement and/or shows requirement and shows some requirement and demonstrates
insufficient evidence of good evidence of good management skills. consistent, efficient, and thoughtful use
management skills. of time and skills.
Total Score

Mean Score = (Total Score / 3)

Percentage Rating = (Total Score /9 ) x 100%

Evaluated by:

Printed Name and Signature of Faculty Member Date