Lecture Notes - Chapter 9
Oscillators
(These Lecture Notes are for courses using the book the Complete Electronics Self-Teaching Guide with Projects. Instructors of courses using that text are permitted to use these Lecture Notes as-is or adapt them for their use).
- Understanding Oscillators
- Discuss the three sections of an oscillator.
- Introduce the term: negative feedback (figure 9.3).
- Introduce the term: positive feedback (figure 9.4).
- Positive feedback can cause an amplifier to oscillate even when there is no external input.
- Introduce the term: resonant load (figure 9.8).
- Feedback
- Discuss the feedback method used in a Colpitts oscillator (figure 9.11 (1)).
- Discuss the feedback method used in a Hartley oscillator (figure 9.11 (2)).
- Discuss the feedback method used in an Armstrong oscillator (figure 9.11 (3)).
- The Colpitts Oscillator
- Discuss the Colpitts oscillator circuit (figure 9.15).
- Feedback is taken from a connection between the two capacitors in the resonant circuit.
- Review the equation used to calculate the resonance frequency of a Colpitts oscillator.
- Review the equation used to determine the fraction of the output voltage used as feedback in the Colpitts oscillator.
- Project 9.1: The Colpitts Oscillator
- Discuss the objective of the project.
- Review the circuit diagrams (figure 9.18 and 9.19).
- Review the test setup (figure 8.21).
- Discuss how to calculate the frequency from the measured period.
- The Hartley Oscillator
- Discuss the Hartley oscillator circuit (figure 9.27).
- Feedback is taken from a tap partway down the coil, or if two inductors are used, a connection between the two inductors in the resonant circuit.
- Discuss the Hartley oscillator circuit (figure 9.27).
- Project 9.2: The Hartley Oscillator
- Discuss the objective of the project.
- Review the circuit diagram (figure 9.30).
- Review the test setup (figure 9.32)
- The Armstrong Oscillator
- Discuss the Armstrong oscillator circuit (9.35).
- Simple Colpitts Oscillator Design Procedure
- Review the equation to determine the value of C1.
- Discuss the calculation to determine the value of C2.
- Discuss the calculation to determine the value of RC.
- Discuss the calculation to determine the value of CC and CB.
This page includes material extracted, by permission of the publisher, Wiley Publishing, from Complete Electronics Self-Teaching Guide with Projects, ISBN: 9781118217320.
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