Scope Waveform Analysis (1963) -- Contents and Intro

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CONTENTS:

1. INTRODUCTION

Unexplained Hum Interference - Pulsating Pattern - Scope Oscillates - Hooked Base Line - Spurious Pip on Sine-wave Deflection - Waveform Changes with Step-attenuator Setting - Low-capacitance Probe Distorts Waveform - Probe Weakens Signal Excessively - Getting Acquainted with Waveforms

2. FUNDAMENTAL CONCEPTS

Capabilities of the Oscilloscope - Basic Electrical Quantities - What is a Waveform? - Sine-Wave Voltage Sources - Marking Time and Instantaneous Voltages - Synchronization -Frequency Versus Repetition Rate - General Waveform Characteristics - Pattern Brightness Versus Beam Speed - Waveform Proportions - Basic Facts of Complex Waveforms -Waveforms Containing Straight Lines - Principles of Wave Analysis - Ringing Out the Harmonics in a Waveform - What is Rise Time? - Rise Time Versus Frequency Response

3. BASIC WAVEFORM CHARACTERISTICS

Peak-to-peak, RMS, and DC Values - Resistance Waveforms - Principles of Differentiation - Basics of RC Circuit Analysis - Kirchhoff's Law - Voltage and Current Waveforms -Differentiation and Integration of Sine Waves - Transient and Steady States of Sine Waves - Elimination of the Transient Interval - Combined Differentiation and Integration

4. WAVESHAPING PRINCIPLES AND ANALYSES

Waveshaping with Resonant Circuits - scope Frequency Response - Time Markers from Ringing Circuit - Waveshaping with RC Circuitry - Waveshaping by Nonlinear Resistance - Linearizing Waveshapers - Waveshaping for Impedance Load- Differential Mixer - Waveshapers in Radar Timers

5. WAVEFORM TYPES AND ASPECTS

Aspects of a Waveform - Meaning of Power Factor - Mixed Waveforms – Non-recurrent Transient Waveforms - Frequency Indication - Aspect Control - One Scope Checks Another - Modulation Cyclogram Aspects - Transistor Characteristics -Tube Characteristics - Hum in Waveforms - Color Waveform Aspects

6. WAVEFORM MEASUREMENTS

How to Measure db with a Scope - Percentage Overshoot -Harmonics and Ringing Frequency - Analysis of Odd and Even Harmonics - Q Value of a Coil - AC Resistance - Untuned Transformer - Leakage Reactance - Delay Time - Use of Expanded Display - Waveforms for Large Inductances -Viewing Total Harmonic Distortion - Measurement of DC Component - Chroma Phase Measurement - Phase Checks with Keyed-Rainbow Signal

7. WAVEFORM DISTORTION ANALYSIS

Reactance Versus Frequency - Stray-field Pickup Considerations - Waveform Distortion Due to Nonuniform Tube Characteristics - Evaluating Small Amounts of Distortion -Transient Distortion - Waveform Deterioration - Waveform Contamination - Sync Separation - Color-burst Waveform - When Waveshape is Important - Band-width Versus Sync-pulse Reproduction - Color-bar Signal in Black-and-White Tests - Peak-to-peak Voltages Versus DC Voltages - Troubleshooting by Waveform Aspect - Interference Pickup Versus Circuit Impedance



This guide is based on the above Sams 1963/1965 book.

The oscilloscope is an indispensable tool for analyzing electronic circuit operation. The full value of the scope can only be realized, however, if the operator is able to properly analyze and interpret the waveforms he obtains on the scope screen. Analysis of waveforms requires on understanding of the fundamentals of scope operation, as well as a knowledge of the nature of the waveforms themselves and of the circuit, in which they are found.

Providing complete coverage of the subject, the content of this book begins with a general introduction to the subject of scope waveform displays, and fundamental concepts of waveforms and circuits. Subsequent Sections discuss in more detail basic waveform characteristics, waveshaping principle, and analyses, waveform type, and aspect waveform measurements, and waveform distortion analysis. These Sections describe the characteristic, of waveforms, circuit. for producing them, the way they ore d by the scope, and how waveforms give indication, of the nature of circuit defect.

Concentrating heavily on the practical aspect of obtaining and analyzing electronic circuit waveforms, this volume is a reference handbook of value to all electronic technicians and engineer.

AUTHOR: Bob Middleton is one of the few full-time professional free-lance technician writers in the electronics field. His many books have proven invaluable to technicians and engineers because they are based on his own practical experience. His home workshop is filled with a wide variety of test instruments, receivers, and other equipment which he uses In develop faster and easier ways to diagnose electronic equipment troubles.

PREFACE:

Whenever you use an oscilloscope you must be able to analyze and interpret the waveform patterns; otherwise, observations provide no information. If you are adept at pattern analysis, a scope provides much more data than any other basic electronic instrument. In the simplest cases, analysis consists merely of noting the pattern amplitude. Usually, you will be concerned with the waveshape, which may be as uncomplicated as an ideal sine or square wave. When accompanied by some type of distortion (for example, a sine wave might be clipped) it may be mixed with identifiable interference; it may display a parasitic "bulge"; it may show the effects of crossover distortion; or its contour may differ slightly from the ideal.

A square wave might display overshoot, perhaps accompanied by ringing; the top may be tilted, curved, or both; corners might be rounded; an interval of parasitic oscillation may be observed; the rise time of the square wave might be slow; the wave may be mixed with hum voltage or other spurious interference; or a reproduced square wave might be distorted due to circuit nonlinearity. Circuit response at one square-wave repetition rate is usually different from its response at some other repetition rate.

There is a vital consideration behind all waveform distortions and attenuations. Every effect has its cause and if you know how to analyze the effect, you can proceed without hesitation to its cause. There is no easy road to scope trace analysis. Proficient analysis is based on an understanding of Ohm's law, both for DC and AC circuits. In some cases recourse must also be made to Kirchhoff's law. When dealing with AC circuits, you will find that Ohm's law involves phase and frequency, as well as voltage, current, and resistance. Frequency and phase enter into the analysis when reactance is present, as in inductive or capacitive circuits.

In general, you can do better work with better tools. A "sophisticated" scope with extended bandwidth and DC response provides more information than an AC scope with limited bandwidth. Still more data is provided by advanced operating features, such as calibrated and triggered sweeps. However, this book is concerned chiefly with waveforms displayed by the better class of low-cost scopes. A scope with reasonably flat response out to 4 mhz is satisfactory for most work, including the analysis of color-TV waveforms.

Patterns can be completely misleading, unless the scope is applied properly. Circuit loading will be a problem unless a low-capacitance probe is used to test medium- and high-impedance circuits. Certain classes of tests cannot be made without the use of a demodulator probe. Inasmuch as these requirements are incidental to the main topic of this book, beginners are directed to specialized texts for information on scope probes and applications.

By ROBERT G. MIDDLETON; April, 1963


Also see:

Troubleshooting With the Oscilloscope

Transistor Circuits (1964)

Advanced Radio Control (1965)

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