Oscillators

Table of Contents

Chapter 1: Introduction to Oscillators

Topics: Oscillation; Oscillators and amplifiers; Classes of oscillators; Common oscillator circuits

Learning Objectives:

• Describe the conditions needed to start and to sustain oscillation.
• Explain how positive feedback affects oscillation.
• Name three kinds of feedback networks used in oscillators.
• Discuss the advantages and disadvantages of tuned circuits, phase-shift oscillators, and crystal oscillators.
• Describe several common oscillator circuits.

Chapter 2: Flip-Flops

Topics: Square waves; Switching circuits; One-shots; Astable flip-flops (multivibrators); Frequency of multivibrators; Bistable flip-flops

Learning Objectives:

• Discuss the differences between sine wave oscillators and square wave switching circuits.
• Explain how rise time and the time constant affect flip-flop circuits.
• Compare the operation of discrete transistor one-shots and IC one-shots.
• Explain how IC pairs of one-shots or IC op amps form an astable multivibrator.
• Describe the operation of bistable flip-flops.

Chapter 3: Logic Clocks

Topics: Combinational and synchronous logic; Clock conditioning; Schmitt trigger circuit; Frequency dividers; Multiphase and real world logic clocks

Learning Objectives:

• Compare combinational logic, synchronous logic, and sequential logic.
• Explain how logic clocks are generated.
• Explain how negative resistance enables the UJT relaxation oscillator to be used as a logic clock.
• Discuss the effect of hysteresis on logic clock operation and describe the operation of the Schmitt trigger circuit.
• Describe the operation of ripple counters and other frequency dividers.
• Discuss problems caused by real-world (nonideal) logic clocks.

Chapter 4: Filters and Waveforms

Topics: Wave shaping; Simple, RC low-pass, RL low-pass, high-pass, band-pass, band-reject, and active filters; Time constants; Differentiators and integrators; Function generators

Learning Objectives:

• Discuss the composition of waveforms and explain how filters change the shapes of waveforms.
• Compare the frequency characteristics of low-pass and high-pass filters and of band-pass and band-reject filters.
• Discuss the calculation of time constants in timing circuits.
• Describe methods of creating and shaping complex waveforms, including the differentiator and integrator circuits.
• Explain briefly how digital waveforms are generated with a microprocessor.

Chapter 5: Troubleshooting Oscillators

Topics: Test equipment; Tracing oscillator operation; Troubleshooting multivibrators, one-shots, flip-flops, sequential logic circuits, clocks, and filters

Learning Objectives:

• Discuss the basic requirements of four kinds of equipment used to test oscillators.
• Describe good general practices in troubleshooting oscillator components and circuits.
• Describe the steps in tracing oscillator circuit operation and selecting test points for monitoring waveforms.
• Discuss the steps in troubleshooting multivibrators, one-shots, and flip-flops.
• Discuss troubleshooting methods for sequential logic circuits, including clocks.
• Discuss troubleshooting methods for frequency dividers and filters.

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