Electronic Measurements & Instrumentation

Description

Cover Brief Contents Contents Foreword Preface Acknowledgements About the Author Chapter 1: Measurements and Instruments 1.1 Introduction 1.2 Terminology 1.2.1 Advantages of Instrumentation Systems 1.2.2 Block Schematics of Measuring Systems 1.2.3 Other Systems 1.2.4 Objectives of Measurement 1.2.5 Comparison between Analog and Digital Instruments 1.2.6 Factors for the Selection of Analog and Digital Equipments 1.3 Performance Characteristics 1.3.1 Definitions 1.4 Significant Figures 1.5 Dynamic Characteristics 1.6 Types of Errors 1.6.1 Gross Errors 1.6.2 Systematic Errors 1.6.3 Random Errors 1.7 Statistical Analysis 1.7.1 Probability of Errors and Gaussian Curve 1.8 Measurement Standards 1.9 Suspension Galvanometer 1.10 D’Arsonval Movement 1.10.1 Taut-Band Suspension 1.10.2 Temperature Compensation 1.10.3 Shunt Resistor 1.10.4 Ayrton Shunt 1.11 Direct Current Meters 1.12 D’Arsonval Meter Movement Used in DC Voltmeters 1.12.1 Ammeter Loading Effect 1.13 DC Voltmeters 1.13.1 Multirange Voltmeter 1.14 Ohmmeter 1.14.1 Series-Type Ohmmeter 1.14.2 Shunt-Type Ohmmeter 1.14.3 D’Arsonval Meter Movement Used in Ohmmeter 1.14.4 Multiple Range Ohmmeters 1.14.5 Electrolyte Capacitor Leakage Tests 1.14.6 For Non-Electrolyte Capacitors 1.15 Multimeter 1.16 Alternating Current-Indicating Instruments 1.16.1 Electrodynamometer 1.17 Rectifier-Type Instruments 1.18 Meter Protection 1.19 Extension of Range 1.20 Frequency Compensation 1.21 Electronic Voltmeter (for DC) 1.22 Electronic Voltmeter (for AC) 1.22.1 Average Reading Voltmeter 1.22.2 Peak Reading Voltmeter 1.22.3 Peak-To-Peak Detector 1.23 DC Meter with Amplifier 1.24 Chopper-Stabilised Amplifier 1.25 AC Voltmeter using Rectifiers 1.26 True RMS-Responding Voltmeter 1.27 Balanced Bridge Voltmeter (VTVM) 1.27.1 Advantages 1.27.2 Disadvantages 1.28 Transistor Voltmeter (TVM) 1.29 Electronic Multimeter 1.29.1 Resistance Ranges 1.30 AC Current Measurement 1.30.1 Differential Voltmeter 1.31 Differential Amplifier 1.32 Alternating Current Instruments (AC Meters) 1.32.1 D’Arsonval Meter Movement for AC Circuit 1.32.2 Modified Circuit for AC Measurements 1.32.3 D’Arsonval Meter Movement Circuit (FWR) 1.33 Electrodynamometer Movement 1.33.1 Transfer Instruments 1.33.2 Iron Vane-Meter Movement 1.34 Thermocouple Meter 1.34.1 Constant Voltage Source 1.34.2 Constant Current Source 1.34.3 Volt Box 1.34.4 Factors to be Considered in the Selection of an Analog Voltmeter 1.35 Digital Voltmeters 1.35.1 General Specifications 1.36 Ramp-Type DVM 1.37 Staircase Ramp-Type DVM 1.38 Dual Slope Integrating-Type DVM 1.39 Successive-Approximation Conversion (SAC) 1.39.1 Block Schematic 1.40 Continuous Balance-Type DVM 1.41 Automatic Polarity Indication for DVM 1.42 Autoranging for DVM 1.42.1 Typical Case 1.43 3 3 4 Digit Display 1.44 Picoammeter 1.44.1 Applications 1.45 Low-Current Ammeter Applications 1.45.1 Wafer-Level Photodiode Testing 1.45.2 Monitoring and Control of Focused Ion Beam Currents 1.46 High-Resistance Measurements 1.47 Summary Points to Remember Objective-type Questions Review Questions Unsolved Problems Chapter 2: Waveform Generators 2.1 Introduction 2.2 Considerations in Choosing an Oscillator or Signal Generator 2.3 Sine Wave Generator 2.4 Oscillator Circuit 2.5 Attenuator 2.6 Frequency-Synthesised Signal Generator 2.7 Sweep-Frequency Generator 2.8 Pulse and Square Wave Generator 2.9 Function Generator 2.10 Arbitrary Waveform Generator 2.10.1 Applications 2.11 Video Signal Generator 2.12 Summary Points to Remember Objective-type Questions Review Questions Unsolved Problems Chapter 3: Signal Analysers 3.1 Introduction 3.2 Wave Analyser 3.3 AF Wave Analyser 3.4 High-Frequency Wave Analyser 3.4.1 Frequency Mixers 3.5 Harmonic Distortion 3.5.1 Tunable Selective Circuit 3.5.2 Disadvantages 3.5.3 Heterodyne Wave Analyser (Wavemeter) 3.5.4 Fundamental Suppression Method of Distortion Measurement 3.6 Heterodyne Wave Analyser 3.6.1 Applications of Wave Analysers 3.7 Tuned Circuit Harmonic Analyser 3.8 Heterodyne Harmonic Analyser or Wavemeter 3.9 Fundamental Suppression Harmonic Distortion Analyser 3.10 Spectrum Analyser 3.10.1 Characteristics of a Spectrum Analyser 3.10.2 Applications of a Spectrum Analyser 3.10.3 Basic Spectrum Analyser 3.10.4 Factors to be Considered in a Spectrum Analyser 3.11 Low-Frequency Spectrum Analyser 3.11.1 Applications 3.12 Power Analyser 3.12.1 Communications Signal Analyser 3.12.2 Logic Analysers 3.12.3 Network Monitoring System 3.12.4 System Architecture 3.12.5 Features 3.12.6 Applications 3.13 Capacitance–Voltage Analysers 3.14 Oscillators 3.14.1 Considerations in Choosing an Oscillator 3.15 Summary Points to Remember Objective-type Questions Review Questions Unsolved Problems Chapter 4: Oscilloscopes 4.1 Introduction 4.2 Cathode Ray Oscilloscope 4.3 Block Diagram of a CRO 4.4 Cathode Ray Tube (CRT) 4.5 Graticules 4.6 Electrostatic Deflection Sensitivity 4.6.1 Design Criteria 4.7 Different Controls in a CRO 4.7.1 How to Operate a CRO 4.8 Time Base Generators 4.8.1 Time Base Circuits 4.9 Triggered Mode 4.9.1 Free-Running Mode 4.9.2 Synchronisation of the Sweep Circuit 4.9.3 Types of CROS 4.9.4 Sections of CRTs 4.9.5 Deflection Sensitivity Equation 4.10 Neon Time Base Circuit 4.10.1 Frequency of Neon Time Base 4.10.2 Neon Lamp 4.10.3 Free-Running Mode of CRO 4.10.4 Using CRO in Triggered Mode 4.10.5 Automode of Sweep 4.10.6 Normal Mode 4.11 Time Base Circuit for a General-Purpose CRO 4.11.1 Synchronisation Issues 4.11.2 Line Synchronisation 4.12 Lissajous Figures 4.13 Types of CRO Probes 4.13.1 Direct Probe 4.13.2 High-Impedance Probe 4.13.3 Detector Probe 4.13.4 High-Voltage Probe 4.14 High-Frequency CRO Considerations 4.15 Delay Lines in CROs 4.15.1 Lumped Parameter Delay Line 4.15.2 Distributed Parameter Delay Line 4.16 Applications of CRO 4.17 Summary Points to Remember Objective-type Questions Review Questions Unsolved Problems Chapter 5: Special Types of CROs 5.1 Special Types of Oscilloscopes 5.2 Dual Beam CRO 5.3 Dual Trace CRO 5.4 Sampling Oscilloscope 5.4.1 Sampling Oscilloscopes — Vertical and Time Base 5.4.2 Sampling Vertical 5.4.3 Sampling Time Base 5.5 Storage Oscilloscopes 5.5.1 Mesh Storage 5.5.2 Variable Persistence 5.5.3 Phosphor Storage 5.5.4 Phosphor Characteristics 5.5.5 Persistence of Phosphor Materials 5.5.6 CRO Subsystems 5.6 Digital Storage CRO 5.6.1 CRO Probes 5.7 Frequency/Period-Timer/Counter Circuit 5.8 Frequency Measurement 5.9 Period Measurement 5.9.1 Advantages 5.10 Errors in Frequency/Period Measurements 5.10.1 Errors Because of Crystal Stability 5.11 Universal Counters 5.12 Extending the Range of Frequency Counters 5.13 Glossary 5.14 The ABC’s of Oscilloscopes 5.15 Summary Points to Remember Objective-type Questions Review Questions Unsolved Problems Chapter 6: DC and AC Bridges 6.1 Introduction 6.2 DC Bridges 6.3 Wheatstone Bridge 6.3.1 Operation 6.3.2 Measurement Errors 6.3.3 Thevenin’s Equivalent Circuit 6.4 Kelvin Bridge 6.4.1 Kelvin Double Bridge 6.4.2 Applications 6.5 Strain Gauge Bridge Circuit 6.6 AC Bridges 6.6.1 General Form of Bridge Circuit 6.7 Maxwell Bridge 6.7.1 Phasor Diagram for the Maxwell Bridge 6.8 Hay Bridge 6.8.1 Phasor Diagram for Hay Bridge 6.9 Schering Bridge 6.9.1 Phasor Diagram for a Schering Bridge 6.10 Wien Bridge 6.10.1 Phasor Diagram for the Wien Bridge 6.11 Anderson Bridge 6.12 Resonance Bridge 6.13 Similar Angle Bridge 6.14 Radio Frequency Bridge (Subtitution Technique) 6.15 Wagner’s Ground Connection 6.16 Twin-T Null Network 6.17 Bridged-T Network 6.18 Detectors for AC Bridges 6.19 Phasor Diagrams 6.20 Recorders 6.20.1 Introduction 6.21 Strip-Chart Recorders 6.21.1 Galvanometric Recorders 6.21.2 Sensitivity 6.21.3 Transient Response 6.22 Pen-Driving Mechanism 6.23 Other Features 6.24 Servorecorders 6.25 Servobalancing Potentiometric Recorder 6.26 Characteristics of Typical Servorecorders 6.27 Oscillographic Recorders 6.28 Magnetic Tape Recorders 6.28.1 Direct AM Recording 6.28.2 Frequency Modulation Recording 6.29 Recorders (Contd.) 6.29.1 X–Y Recorders 6.29.2 Self-Balancing Potentiometers 6.29.3 Working of a Servotype Motor 6.29.4 Chopper 6.29.5 Servotype X–Y Recorders 6.29.6 Y-Scale 6.30 Galvonometer Oscillographs 6.30.1 Applications 6.31 Summary Points to Remember Objective-type Questions Review Questions Unsolved Problems Chapter 7: Transducers 7.1 Introduction 7.1.1 Examples 7.2 Classification of Transducers 7.3 Active and Passive Transducers 7.3.1 Factors that Affect the Performance of a Transducer 7.3.2 Applications 7.4 Force and Displacement Transducers 7.4.1 Potentiometer 7.4.2 Potentiometric Transducer 7.4.3 Loading Effect on a Potentiometer 7.4.4 Resolution 7.4.5 Linear Potentiometers 7.4.6 Non-Linear Potentiometers 7.4.7 Noise 7.5 Resistance Strain Gauges 7.6 Bonded-Type Strain Gauges 7.6.1 Filament Construction 7.6.2 Materials of the Filament Wire 7.6.3 Base Carrier Material 7.6.4 Strain Gauge Cements 7.6.5 Temperature Effect on Strain Gauges 7.6.6 Measurement of Strain 7.6.7 Strain Gauge Circuitry 7.6.8 The Ballast Circuit 7.6.9 The Wheatstone Bridge Circuit 7.6.10 Circuit for Calibration 7.6.11 Mounting of Strain Gauges 7.6.12 Commercial Strain-Measuring Systems 7.6.13 Stress Measurement on Rotating Members 7.6.14 Special Problems in Strain Gauge Applications 7.6.15 Semiconductor Strain Gauges 7.7 Summary Points to Remember Objective-type Questions Review Questions Unsolved Problems Chapter 8: Other Types of Transducers 8.1 Introduction 8.2 Resistance Thermometers 8.2.1 Self-Heating 8.2.2 Advantages of Wire Resistance Thermometers 8.2.3 Disadvantages 8.3 Semiconducting-Resistance Temperature Transducers (Thermistors) 8.3.1 Circuit Employed 8.3.2 Advantages 8.3.3 Disadvantages 8.4 Hot Wire Anemometer 8.4.1 Constant Current Type 8.4.2 Measurement of Direction of Average Flow 8.5 Other Variable Resistance Transducers 8.5.1 Contact Pressure Transducer 8.5.2 Humidity Measurement 8.5.3 Light 8.6 Variable Inductance Transducers 8.6.1 Linear Variable Differential Transformer (LVDT) 8.6.2 Applications of LVDT 8.6.3 LVDT Load Cells 8.7 Synchros 8.8 Variable Reluctance Accelerometer 8.8.1 Microsyn 8.9 Temperature Measurement 8.9.1 Electric Methods 8.9.2 Electrical Methods 8.10 Thermocouples 8.10.1 Thermocouple Junction 8.10.2 Thermocouple Insulation 8.10.3 Soldered, Drawn, or Rolled Sheathed Thermocouple Construction 8.10.4 Disposable-Tip Thermocouples 8.10.5 Homogeneity of Thermocouple Wires 8.10.6 Installation of Thermocouples 8.10.7 Cold Junction Compensation 8.10.8 Resistance Thermometry 8.11 Platinum Resistance Th ermometers 8.12 Special Resistance Thermometer 8.12.1 Performance and Testing Procedure 8.12.2 Insulation Resistance 8.12.3 Vibration Resistance 8.13 Thermistors 8.13.1 Thermistor Construction Techniques 8.13.2 Thermistor Performance Characteristics 8.13.3 Applications of Thermistor 8.13.4 Sensistors 8.14 Digital Temperature-Sensing System 8.15 Miscellaneous Transducers 8.15.1 Flow Measurements 8.15.2 Ultrasonic Flow Meters 8.15.3 Electromagnetic Flow Meter 8.15.4 Theory of Head Flow Meters 8.15.5 Various Tap Connections 8.15.6 Advantages and Limitations 8.15.7 Characteristics of Head Flow Meters 8.16 Area Flow Meters 8.16.1 Rotameters 8.16.2 Piston-Type Area Meter 8.16.3 Laser Doppler Anemometer (LDA) 8.17 Positive Displacement Meters 8.17.1 Basic Requirements 8.17.2 Nutating Piston Meters 8.17.3 Rotating Meters 8.17.4 Oscillating Piston Meters 8.18 Magnetic Flow Meter 8.18.1 Flow Meter Requirements 8.19 Variable Capacitance Transducers 8.19.1 Advantages of Capacitance Transducers 8.19.2 Practical Capacitor Pickups 8.19.3 Feedback-Type Capacitance Pickup 8.19.4 Carbon Microphone 8.19.5 Circuitry for Capacitance Transducers 8.19.6 Frequency-Modulating Oscillator Circuit 8.19.7 Circuits Using DC Excitation 8.19.8 AC Bridges for Amplitude Modulation 8.19.9 Pulsewidth-Modulating Circuit 8.20 Piezoelectric Transducer 8.20.1 Materials 8.20.2 Equivalent Circuit 8.20.3 Piezoelectric Coefficients 8.20.4 Modes of Deformation 8.20.5 Multiple Arrangements (Stacks) 8.20.6 Bimorphs 8.20.7 Bimorph Twisters 8.20.8 General Form of Piezoelectric Transducers 8.20.9 Available Typical Piezoelectric Accelerometers 8.20.10 Shock Accelerometer 8.20.11 Environmental Effects 8.21 Magnetostrictive Transducers 8.21.1 Magnetostrictive Materials 8.21.2 Practical Forms of Transducers 8.21.3 Magnetostrictive Torque Transducers 8.21.4 Errors 8.21.5 Temperature 8.21.6 Variation of Supply Voltage 8.21.7 Eddy Currents 8.21.8 Input Impedance 8.22 Liquid-Level Measurement 8.22.1 Direct Methods 8.22.2 Indirect Liquid-Level Measurement 8.22.3 Capacitance-Level Gauge 8.23 Ultrasonic-Level Gauge 8.24 Measurement of Humidity and Moisture 8.25 Photoconductive Cells 8.26 Photo Pulse Pickup 8.27 Digital Encoders and Encoder Transducers 8.27.1 Shaft Position Encoders 8.27.2 Encoder Transducers 8.28 Fibre Optic Displacement Transducer 8.28.1 Absolute Motion Devices 8.28.3 Measurement of Velocity 8.28.4 Translational Velocity Transducer Moving Coil Pickup 8.29 DC Tachometer Generators for Rotary Velocity Measurement 8.29.1 AC Tachogenerator for Rotary Velocity Measurement 8.30 Force Measurements 8.30.1 Balance 8.30.2 Elastic Force Devices 8.31 Electromechanical Methods 8.32 Measurement of Pressure 8.32.1 Moderate Pressure Measurement 8.32.2 Manometers 8.33 Elastic Transducers 8.34 High-Pressure Measurement 8.35 Low-Pressure Measurement (Vacuum Measurement) 8.35.1 Thermal Conductivity Gauge or Pirani Gauge 8.36 Temperature Measurements 8.37 Data Acquisition Systems 8.38 Summary Points to Remember Objective-type Questions Review Questions Unsolved Problems Appendix A: Answers to Objective-Type Questions References Index