artofelectronics ch1
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Questions and Answers

What is the field of electronics considered to be?

  • A declining field of study
  • One of the great success stories of the 20th century (correct)
  • A relatively new field of study
  • A minor field of study

    • What was the primary technology used in the first half-century of electronics?

  • Solid-state electronics
  • Vacuum-tube electronics (correct)
  • Integrated circuits
  • Transistors

    • What is the term used to describe the integration of many transistors in a single chip?

  • SI (Small-Scale Integration)
  • MSI (Medium-Scale Integration)
  • LSI (Large-Scale Integration)
  • VLSI (Very Large-Scale Integration) (correct)

    • What is the trend observed in the cost of electronic microcircuits?

    <p>The cost decreases to a fraction of its initial cost</p> Signup and view all the answers

    What is the primary focus of this book?

    <p>To convey the excitement and know-how of electronics</p> Signup and view all the answers

    What is the term used to describe the combination of displays, lasers, and other components?

    <p>Optoelectronics</p> Signup and view all the answers

    What is the result of the manufacturing process being perfected in electronic microcircuits?

    <p>Decreased cost</p> Signup and view all the answers

    What was the cost of an IBM 650 mid-century computer?

    <p>$300,000</p> Signup and view all the answers

    What is the primary application of solid-state electronics?

    <p>All of the above</p> Signup and view all the answers

    What is the main challenge in understanding electricity?

    <p>It is difficult to visualize</p> Signup and view all the answers

    Why is the first chapter considered the most mathematical?

    <p>Because it is an introduction to circuit design and behavior</p> Signup and view all the answers

    What is the purpose of including intuition-aiding approximations in the new edition?

    <p>To foster a good intuitive understanding of circuit design and behavior</p> Signup and view all the answers

    What is the benefit of introducing active components early in the textbook?

    <p>It makes it possible to jump into exciting applications</p> Signup and view all the answers

    What is the assumption made about the reader's prior knowledge of electronics in this chapter?

    <p>The reader has no prior knowledge of electronics</p> Signup and view all the answers

    What is the main focus of the chapter after the foundations of electronics are established?

    <p>Active circuits</p> Signup and view all the answers

    What is the weight of the IBM 650 mid-century computer?

    <p>2.7 tons</p> Signup and view all the answers

    What is the power rating of the vitreous enamel resistor with leads in the top row?

    <p>20W</p> Signup and view all the answers

    What is the type of resistor shown at the bottom of the image?

    <p>Metal-film</p> Signup and view all the answers

    What is the correct equation for instantaneous power?

    <p>P = V * I</p> Signup and view all the answers

    What is the term that should not be used to describe current?

    <p>Amperage</p> Signup and view all the answers

    What type of resistors are shown in the middle row?

    <p>Wirewound power resistors</p> Signup and view all the answers

    What is the term that should not be used to describe resistance?

    <p>Ohmage</p> Signup and view all the answers

    What is the unit of measure for voltage?

    <p>Volt</p> Signup and view all the answers

    What is the equivalent of moving a unit charge from the more negative point to the more positive point?

    <p>Work done</p> Signup and view all the answers

    What is the rate of flow of electric charge past a point?

    <p>Current</p> Signup and view all the answers

    How many electrons are approximately equal to 1 coulomb of charge?

    <p>6×10^18</p> Signup and view all the answers

    What is the energy released when a unit charge moves from the higher potential to the lower potential?

    <p>1 J</p> Signup and view all the answers

    What is the equivalent of a current of 1 amp?

    <p>A flow of 1 coulomb of charge per second</p> Signup and view all the answers

    What is the term used to describe a potential difference?

    <p>Electromotive Force</p> Signup and view all the answers

    What is the unit of energy when moving a unit charge through a potential difference of 1 V?

    <p>Joule</p> Signup and view all the answers

    What is the direction of current flow in a circuit?

    <p>From a more positive point to a more negative point</p> Signup and view all the answers

    What is the correct way to refer to voltage in a circuit?

    <p>Between two points</p> Signup and view all the answers

    What is the purpose of an oscilloscope?

    <p>To visualize voltages or currents as a function of time</p> Signup and view all the answers

    What is the sum of the currents into a point in a circuit?

    <p>Equal to the sum of the currents out</p> Signup and view all the answers

    What is the voltage across devices connected in parallel?

    <p>The same for each device</p> Signup and view all the answers

    What is the formula for power consumed by a circuit device?

    <p>P = V I</p> Signup and view all the answers

    What is the unit of power?

    <p>Joules per second</p> Signup and view all the answers

    What happens to the power consumed by a circuit device?

    <p>It is converted into heat, mechanical work, or radiated energy</p> Signup and view all the answers

    What is the assumption about the voltage on a wire in a circuit?

    <p>It is the same at every point on the wire</p> Signup and view all the answers

    What is Kirchhoff's voltage law?

    <p>The sum of the voltage drops around a closed circuit is zero</p> Signup and view all the answers

    What is the relationship between voltage and current in a resistor?

    <p>I is proportional to V</p> Signup and view all the answers

    What type of devices control the current that can flow between a pair of terminals by the voltage applied to a third terminal?

    <p>Transistors</p> Signup and view all the answers

    What is an example of a temperature-dependent resistor?

    <p>Thermistor</p> Signup and view all the answers

    What is the name of the resistor shown in Figure 1.3?

    <p>A resistor</p> Signup and view all the answers

    Why is the term 'amperage' not preferred in electronics?

    <p>Because it is only used by power engineers</p> Signup and view all the answers

    What is the term that should not be used to describe resistance?

    <p>Ohmage</p> Signup and view all the answers

    What is the equivalent form of Ohm's law that relates power, voltage, and resistance?

    <p>P = I²R</p> Signup and view all the answers

    What is the minimum wall-plug voltage according to the ANSI standard C84.1?

    <p>110 V</p> Signup and view all the answers

    What is the ratio of measured output to applied input in an amplifier circuit?

    <p>Transfer function</p> Signup and view all the answers

    What is the resistance of a heavy power cable made of pure copper per foot?

    <p>0.05 μΩ</p> Signup and view all the answers

    What is the unit of measure for the energy released when a unit charge moves from a higher potential to a lower potential?

    <p>Joule</p> Signup and view all the answers

    What is the power lost per foot due to I²R losses in a cable?

    <p>P = I²R per foot</p> Signup and view all the answers

    What is the term used to describe a circuit that accepts an input and produces a corresponding output?

    <p>Input-output circuit</p> Signup and view all the answers

    What is the purpose of a voltage divider circuit?

    <p>To reduce an input voltage</p> Signup and view all the answers

    What is the primary function of resistors in amplifiers?

    <p>To act as loads for active devices</p> Signup and view all the answers

    What is the range of resistances available in resistors?

    <p>0.0002 Ω through 1012 Ω</p> Signup and view all the answers

    What is the most common type of resistor used?

    <p>Metal-film resistor</p> Signup and view all the answers

    What is the effect of putting resistors in series?

    <p>The total resistance increases</p> Signup and view all the answers

    What is the formula for the resistance of several resistors in parallel?

    <p>R = 1/R1 + 1/R2 + 1/R3 + ...</p> Signup and view all the answers

    What is the concept of using a large resistor in series with a small resistor to 'trim' the value of a resistor?

    <p>Shortcut #1</p> Signup and view all the answers

    What is the formula for the resistance of two resistors in parallel?

    <p>R = R1R2 / (R1 + R2)</p> Signup and view all the answers

    What is the unit of measurement for resistance?

    <p>Ohms</p> Signup and view all the answers

    What is the unit of conductance?

    <p>Siemens</p> Signup and view all the answers

    What is the formula for the power dissipated by a resistor?

    <p>P = IV</p> Signup and view all the answers

    What is the purpose of resistors in power circuits?

    <p>To reduce voltages by dissipating power</p> Signup and view all the answers

    What is the limitation of resistors?

    <p>They have variations in resistance with temperature, voltage, time, and humidity</p> Signup and view all the answers

    Why should beginners avoid computing resistor values to many significant places?

    <p>Because the components themselves are of finite precision</p> Signup and view all the answers

    What is the effect of putting resistors in parallel?

    <p>The total resistance decreases</p> Signup and view all the answers

    What is the benefit of using intuition and shortcuts in circuit design?

    <p>It allows for faster and more intuitive circuit design</p> Signup and view all the answers

    What is the notation used to represent a 4.7 kΩ resistor?

    <p>4.7k</p> Signup and view all the answers

    What is the term for the integration of multiple resistors connected across the same voltage?

    <p>Parallel resistance</p> Signup and view all the answers

    What is the relationship between resistance and conductance?

    <p>Conductance is the reciprocal of resistance</p> Signup and view all the answers

    What is the purpose of using approximate calculations in circuit design?

    <p>To simplify the design process</p> Signup and view all the answers

    Why is it beneficial to design circuits that are insensitive to precise component values?

    <p>Because it makes the circuit more reliable</p> Signup and view all the answers

    What is the definition of resistance in terms of voltage and current?

    <p>R = V/I</p> Signup and view all the answers

    What is the unit of measure for voltage?

    <p>Volts</p> Signup and view all the answers

    What is the purpose of resistors in a circuit?

    <p>To convert a voltage to a desired level</p> Signup and view all the answers

    What is the range of values for typical resistors?

    <p>1 ohm to 10 megohms</p> Signup and view all the answers

    What is the prefix for 10^(-6)?

    <p>micro</p> Signup and view all the answers

    What is the term for a device that is characterized by its resistance?

    <p>Resistor</p> Signup and view all the answers

    What is the typical power rating of commonly used resistors?

    <p>1/4 W or 1/8 W</p> Signup and view all the answers

    What is the factor that affects the resistance of a conductor?

    <p>Temperature</p> Signup and view all the answers

    What is the unit of power?

    <p>Watts</p> Signup and view all the answers

    What is the range of values for the prefix 'mega'?

    <p>10^6 to 10^9</p> Signup and view all the answers

    What is the purpose of a voltage divider in a circuit?

    <p>To generate a particular voltage from a larger fixed or varying voltage</p> Signup and view all the answers

    What is the characteristic of a voltage divider circuit?

    <p>The output voltage is always less than or equal to the input voltage</p> Signup and view all the answers

    What type of device can exhibit negative incremental resistances?

    <p>Tunnel diode</p> Signup and view all the answers

    What is the purpose of a potentiometer in a circuit?

    <p>To act as a volume control</p> Signup and view all the answers

    What can be used to represent the output of an amplifier in a voltage divider circuit?

    <p>The input voltage and upper resistance</p> Signup and view all the answers

    What is the advantage of using a voltage divider circuit?

    <p>It can generate a particular voltage from a larger fixed or varying voltage</p> Signup and view all the answers

    What type of circuit can be used to represent a voltage divider circuit?

    <p>Amplifier circuit</p> Signup and view all the answers

    What is the benefit of using a potentiometer in a voltage divider circuit?

    <p>It can generate a varying output voltage</p> Signup and view all the answers

    What is the primary function of a voltage divider circuit?

    <p>To produce a predictable fraction of the input voltage as the output voltage</p> Signup and view all the answers

    What is the relationship between the current and voltage in a voltage divider circuit?

    <p>The current decreases as the voltage decreases</p> Signup and view all the answers

    What is the formula for the output voltage of a voltage divider circuit?

    <p>Vout = Vin × (R2 / (R1 + R2))</p> Signup and view all the answers

    What is the advantage of using an adjustable voltage divider circuit?

    <p>It allows for a variable voltage ratio</p> Signup and view all the answers

    What is the purpose of the signal names 'in' and 'out' in a voltage divider circuit?

    <p>To indicate the input and output voltage levels</p> Signup and view all the answers

    What is the assumption made about the voltage source in a voltage divider circuit?

    <p>The voltage source is fixed</p> Signup and view all the answers

    What is the purpose of the equation I = Vin / (R1 + R2) in a voltage divider circuit?

    <p>To calculate the current flowing through the circuit</p> Signup and view all the answers

    What is the advantage of using a series chain of equal-value resistors with electronic switches in a voltage divider circuit?

    <p>It allows for electrical adjustment of the voltage ratio</p> Signup and view all the answers

    What is the primary characteristic of a real-life voltage source?

    <p>It has an equivalent series resistance.</p> Signup and view all the answers

    What is the purpose of the Thevenin equivalent circuit?

    <p>To simplify a complex circuit.</p> Signup and view all the answers

    What is the typical use of batteries in electronic devices?

    <p>They are used in portable devices only.</p> Signup and view all the answers

    What is the typical characteristic of a battery at the end of its life?

    <p>Its voltage decreases and internal resistance increases.</p> Signup and view all the answers

    What is the advantage of constructing voltage sources using feedback?

    <p>They have far better characteristics.</p> Signup and view all the answers

    What is a characteristic of a perfect voltage source?

    <p>It maintains a fixed voltage drop across its terminals regardless of load resistance.</p> Signup and view all the answers

    What is the behavior of a real voltage source?

    <p>It behaves like a perfect voltage source with a small resistance in series.</p> Signup and view all the answers

    What is the maximum current that a standard 9 volt alkaline battery can provide?

    <p>3 amps</p> Signup and view all the answers

    What is the characteristic of a perfect current source?

    <p>It supplies a constant current regardless of load resistance or applied voltage.</p> Signup and view all the answers

    What is the limitation of a real current source?

    <p>It has a limit to the voltage it can provide.</p> Signup and view all the answers

    What is the preference of a voltage source in terms of load?

    <p>It likes an open-circuit load and hates a short-circuit load.</p> Signup and view all the answers

    What is the preference of a current source in terms of load?

    <p>It likes a short-circuit load and hates an open-circuit load.</p> Signup and view all the answers

    What is the symbol used to indicate a voltage source?

    <p>The symbol shown in Figure 1.9.</p> Signup and view all the answers

    According to Thevenin's theorem, what is the equivalent circuit for a two-terminal network of resistors and voltage sources?

    <p>A single voltage source V in series with a single resistor R.</p> Signup and view all the answers

    How do you find the Thevenin equivalent resistance RTh for a given circuit?

    <p>By dividing the open-circuit voltage by the short-circuit current.</p> Signup and view all the answers

    What is the open-circuit voltage of a voltage divider circuit?

    <p>Vin * (R2 / (R1 + R2))</p> Signup and view all the answers

    What is the short-circuit current of a voltage divider circuit?

    <p>Vin / R1</p> Signup and view all the answers

    What is the Thevenin equivalent resistance of a voltage divider circuit?

    <p>R1 * R2 / (R1 + R2)</p> Signup and view all the answers

    Why is a voltage divider not a good battery?

    <p>Because its output voltage drops severely when a load is attached.</p> Signup and view all the answers

    What is the purpose of Thevenin's theorem?

    <p>To simplify a complex circuit into a simpler equivalent circuit.</p> Signup and view all the answers

    What is the Norton equivalent circuit?

    <p>A current source in parallel with a resistor.</p> Signup and view all the answers

    What is the primary use of a multimeter in a circuit?

    <p>To measure the voltage, current, and resistance of a circuit</p> Signup and view all the answers

    What is the ideal input resistance of a voltmeter?

    <p>Infinite Ω</p> Signup and view all the answers

    What is the purpose of a resistor in a traditional VOM multimeter?

    <p>To put the basic movement in series with the circuit</p> Signup and view all the answers

    What is the typical input resistance of a digital multimeter (DMM) when measuring voltage?

    <p>10 MΩ to 1000 MΩ</p> Signup and view all the answers

    What is the ideal characteristic of a current-measuring meter?

    <p>Zero input resistance</p> Signup and view all the answers

    How do multimeters measure resistance?

    <p>By supplying a small current and measuring the voltage drop</p> Signup and view all the answers

    What is the typical range of voltage measurement in a multimeter?

    <p>From a volt (or less) to a kilovolt (or more)</p> Signup and view all the answers

    What is the typical range of current measurement in a multimeter?

    <p>From 50 μA (or less) to an amp (or more)</p> Signup and view all the answers

    Why is it important to read the specifications of a digital multimeter carefully?

    <p>To understand the input resistance of the meter on different ranges</p> Signup and view all the answers

    What is the purpose of a small resistor in a multimeter when measuring current?

    <p>To create a voltage drop corresponding to the chosen full-scale current</p> Signup and view all the answers

    What is the term used to describe the reduction of the open-circuit voltage by the load?

    <p>Circuit loading</p> Signup and view all the answers

    What should be the ideal relationship between the load resistance and the internal resistance of a source?

    <p>Rload = Rinternal</p> Signup and view all the answers

    What is a common mistake that can lead to a blown-out meter?

    <p>Measuring the current of a voltage source</p> Signup and view all the answers

    What is the result when the load resistance is equal to the internal resistance of the source?

    <p>Maximum power is transferred to the load</p> Signup and view all the answers

    What is the purpose of using a shunt resistance in a meter?

    <p>To convert the meter to a 0-1 A meter</p> Signup and view all the answers

    What is the purpose of making the load resistance high compared to the internal resistance of the source?

    <p>To reduce the attenuation of the signal source</p> Signup and view all the answers

    What is the advantage of using a digital multimeter in measuring extremely low currents?

    <p>It has a very high internal resistance, allowing it to measure low currents</p> Signup and view all the answers

    What is the Thevenin equivalent circuit of a voltage divider?

    <p>A voltage source in series with a resistor</p> Signup and view all the answers

    What is the term used to describe the internal resistance of a signal source?

    <p>All of the above</p> Signup and view all the answers

    What is an example of a device that should have a high resistance load?

    <p>Oscilloscope</p> Signup and view all the answers

    What is the effect of attaching a load resistor to a voltage divider?

    <p>The output voltage decreases</p> Signup and view all the answers

    What is the purpose of using active components like transistors or operational amplifiers in constructing a voltage source?

    <p>To make the voltage source more stiff and resistant to load</p> Signup and view all the answers

    What happens when the load resistance is less than or comparable to the internal resistance of the source?

    <p>The output voltage is decreased</p> Signup and view all the answers

    What is the purpose of maximizing the power transferred to the load?

    <p>To optimize the energy transfer between the source and the load</p> Signup and view all the answers

    What is the result of using a voltage divider with very small resistors?

    <p>The output voltage becomes more stable</p> Signup and view all the answers

    What is the equivalent circuit of a 10k-10k voltage divider driven by a perfect 30 volt battery?

    <p>A perfect 15 volt battery in series with a 10k resistor</p> Signup and view all the answers

    What is the result when the load resistance is equal to zero or infinity?

    <p>Zero power is transferred to the load</p> Signup and view all the answers

    What is the condition for maximum power transfer to the load?

    <p>Rload = Rinternal</p> Signup and view all the answers

    What is the term used to describe a voltage source that does not bend under load?

    <p>Stiff voltage source</p> Signup and view all the answers

    What is the advantage of using a voltage source with a very low internal resistance?

    <p>It is less prone to load changes</p> Signup and view all the answers

    Why is it sometimes not useful to talk about resistance in electronic devices?

    <p>Because I is not proportional to V</p> Signup and view all the answers

    What is the term used to describe the slope of the V–I curve?

    <p>Dynamic resistance</p> Signup and view all the answers

    What is the primary use of a zener diode?

    <p>To create a constant voltage</p> Signup and view all the answers

    What is the dynamic resistance of a zener diode used to quantify?

    <p>Its voltage-regulating ability</p> Signup and view all the answers

    What is the result of a 10% change in applied current on a zener diode with a dynamic resistance of 10 Ω at 10 mA?

    <p>A change in voltage of 10 mV</p> Signup and view all the answers

    What is the unit of the dynamic resistance?

    <p>Ohms</p> Signup and view all the answers

    Why is the dynamic resistance important to know in zener diodes?

    <p>To determine its voltage-regulating ability</p> Signup and view all the answers

    What is the purpose of providing a zener diode with a roughly constant current?

    <p>To create a constant voltage</p> Signup and view all the answers

    What is the ideal behavior of a diode?

    <p>A perfect conductor for current flow in one direction and a perfect insulator for current flow in the same direction.</p> Signup and view all the answers

    What is the function of a zener diode in a circuit?

    <p>To act as a voltage regulator and provide a stable output voltage.</p> Signup and view all the answers

    What is the dynamic resistance of a zener diode?

    <p>It varies roughly in inverse proportion to current.</p> Signup and view all the answers

    What is the advantage of using a current source to drive a zener diode?

    <p>It provides better regulation and makes the zener diode behave more like a perfect voltage source.</p> Signup and view all the answers

    What is the characteristic of low-voltage zener diodes?

    <p>They behave poorly in terms of constancy of voltage versus current.</p> Signup and view all the answers

    What is the alternative to using a zener diode for voltage regulation?

    <p>Using a two-terminal voltage reference.</p> Signup and view all the answers

    What is the equation that relates the change in output voltage to the change in input voltage and current in a zener regulator circuit?

    <p>ΔVout = Rdyn(ΔVin - ΔVout) / (R + Rdyn)</p> Signup and view all the answers

    What is the characteristic of ICs designed to substitute for zener diodes?

    <p>They have a low dynamic resistance.</p> Signup and view all the answers

    What is the purpose of the comparator in the temperature-sensing circuit?

    <p>To switch its output according to the relative voltages at its two input terminals</p> Signup and view all the answers

    What is the characteristic of low-voltage zeners?

    <p>They are pretty dismal, as seen in their measured I vs. V curves</p> Signup and view all the answers

    What is the function of the voltage divider R3R4 in the temperature-sensing circuit?

    <p>To provide a temperature-insensitive reference voltage</p> Signup and view all the answers

    What is the behavior of the LED in the temperature-sensing circuit?

    <p>It behaves like a 1.6 V zener diode</p> Signup and view all the answers

    What is the purpose of the series resistor R5 in the temperature-sensing circuit?

    <p>To limit the current through the LED</p> Signup and view all the answers

    What is the temperature at which the resistance of R4 changes?

    <p>25°C</p> Signup and view all the answers

    What is the characteristic of zener diodes in the neighborhood of 6 V?

    <p>They have a very steep voltage-current curve</p> Signup and view all the answers

    What is the resistance of R4 at 25°C?

    <p>10kΩ</p> Signup and view all the answers

    What type of signals are the most popular around?

    <p>Sinusoidal signals</p> Signup and view all the answers

    What is the unit of frequency in a sinusoidal signal?

    <p>Hertz (Hz)</p> Signup and view all the answers

    What is the mathematical expression for a sinusoidal signal?

    <p>V = Asin(2πft + φ)</p> Signup and view all the answers

    What is the purpose of a comparator in the circuit shown in Figure 1.18?

    <p>To compare the voltage signals at X and Y</p> Signup and view all the answers

    What is the characteristic of a thermistor?

    <p>Its resistance decreases with increasing temperature</p> Signup and view all the answers

    What is the angular frequency measured in?

    <p>Radians per second</p> Signup and view all the answers

    What is the expression for a sinusoidal signal using angular frequency?

    <p>V = Asin(ωt)</p> Signup and view all the answers

    What is the phase of a sinusoidal signal?

    <p>The angle of the signal at time t = 0</p> Signup and view all the answers

    What is the fundamental relation between ω and f?

    <p>ω = 2π f</p> Signup and view all the answers

    What is the characteristic of a linear circuit?

    <p>It always responds with a sinewave</p> Signup and view all the answers

    What is the typical frequency range of sinewaves in electronics?

    <p>From a few hertz to a few tens of megahertz</p> Signup and view all the answers

    What is the purpose of describing the behavior of a circuit by its frequency response?

    <p>To describe the way the circuit alters the amplitude of an applied sinewave as a function of frequency</p> Signup and view all the answers

    What is the frequency range of microwaves?

    <p>Above 2 GHz</p> Signup and view all the answers

    What is the advantage of sinewaves in electronics?

    <p>They are the solutions to certain linear differential equations that describe many phenomena in nature</p> Signup and view all the answers

    What is the result of driving a linear circuit with a sinewave?

    <p>The circuit responds with a sinewave output, but with a changed amplitude and phase</p> Signup and view all the answers

    What is the frequency range of sinewaves that can be generated with special transmission-line techniques?

    <p>Up to 2000 MHz and above</p> Signup and view all the answers

    What is the definition of 0 dB SPL in acoustic measurements?

    <p>A wave with an rms pressure of 20 μPa</p> Signup and view all the answers

    What is the voltage corresponding to 1 mW into a 50 Ω load impedance?

    <p>0.22 V rms</p> Signup and view all the answers

    What is the relationship between Vavg and Vrms for a sinewave?

    <p>Vavg = Vrms/1.11</p> Signup and view all the answers

    What is the term used to describe random noise of thermal origin?

    <p>All of the above</p> Signup and view all the answers

    What is the shape of the amplitude distribution of band-limited white Gaussian noise?

    <p>Gaussian</p> Signup and view all the answers

    What is the type of waveform shown in Figure 1.20A?

    <p>Ramp</p> Signup and view all the answers

    What is the term used to describe a signal that looks like a symmetrical ramp?

    <p>Triangle</p> Signup and view all the answers

    What is the unit of measure for power per hertz in a frequency spectrum?

    <p>Watts</p> Signup and view all the answers

    What is a characteristic of a square wave signal?

    <p>Peak amplitude and rms amplitude are the same</p> Signup and view all the answers

    What is the purpose of specifying a reference amplitude when stating amplitudes in decibels?

    <p>To provide a clear understanding of the measurement</p> Signup and view all the answers

    What is the relationship between the peak-to-peak amplitude and the root-mean-square amplitude of a sine wave?

    <p>The peak-to-peak amplitude is twice the root-mean-square amplitude</p> Signup and view all the answers

    What is the rise time of a step waveform?

    <p>The time required for the signal to go from 10% to 90% of its total transition</p> Signup and view all the answers

    What is the term used to describe a signal that is a combination of a desired signal and random noise?

    <p>Mixed signal</p> Signup and view all the answers

    What is the unit of voltage that is typically used to specify the nominal voltage across the terminals of a wall socket in the United States?

    <p>volts rms</p> Signup and view all the answers

    What is a pulse signal defined by?

    <p>Amplitude and pulse width</p> Signup and view all the answers

    What is the duty cycle of a pulse signal?

    <p>The ratio of pulse width to repetition period</p> Signup and view all the answers

    What is the definition of the decibel (dB) in terms of power?

    <p>dB = 10log10(P2 / P1)</p> Signup and view all the answers

    What is the equivalent decibel change for a signal that is twice the amplitude of another signal?

    <p>+6 dB</p> Signup and view all the answers

    What are the two states present in a digital circuit?

    <p>HIGH and LOW</p> Signup and view all the answers

    What is the input decision threshold of the '74LVC' digital logic family?

    <p>1.5 V</p> Signup and view all the answers

    What is the equivalent decibel change for a signal that is 10 times the amplitude of another signal?

    <p>+20 dB</p> Signup and view all the answers

    What is the equivalent decibel change for a signal that is one-tenth the amplitude of another signal?

    <p>-20 dB</p> Signup and view all the answers

    What is a step function?

    <p>A part of a square wave</p> Signup and view all the answers

    What is the purpose of specifying legal HIGH and LOW states in digital electronics?

    <p>To distinguish between the two possible states</p> Signup and view all the answers

    What is the formula for calculating the decibel change in terms of amplitude?

    <p>dB = 20log10(A2 / A1)</p> Signup and view all the answers

    What is the purpose of using a logarithmic measure like the decibel in electronics?

    <p>To deal with ratios as large as a million</p> Signup and view all the answers

    What is the main advantage of using a synthesizer for frequency generation?

    <p>It provides accurate frequency generation</p> Signup and view all the answers

    What is the typical frequency range of a function generator?

    <p>0.01 Hz to 30 MHz</p> Signup and view all the answers

    What is the purpose of a pulse generator?

    <p>To generate pulses with adjustable parameters</p> Signup and view all the answers

    What is the advantage of a programmable function generator?

    <p>It provides increased flexibility and stability</p> Signup and view all the answers

    What is the primary use of capacitors in electronic circuits?

    <p>To filter and block signals</p> Signup and view all the answers

    What is the characteristic of a traditional function generator?

    <p>It uses analog circuitry</p> Signup and view all the answers

    What is the feature of a contemporary function generator?

    <p>It uses digital circuitry</p> Signup and view all the answers

    What is the purpose of a pulse generator in digital circuitry?

    <p>To generate pulses with adjustable parameters</p> Signup and view all the answers

    What is the advantage of using a function generator in electronic circuits?

    <p>It is more flexible than a pulse generator</p> Signup and view all the answers

    What is the primary application of capacitors in electronic circuits?

    <p>To filter, block, and bypass signals</p> Signup and view all the answers

    What is the basic form of a capacitor?

    <p>A pair of closely-spaced metal plates, separated by some insulating material</p> Signup and view all the answers

    What is the relationship between capacitance and plate area?

    <p>Capacitance is proportional to plate area</p> Signup and view all the answers

    What is the unit of capacitance?

    <p>Farad</p> Signup and view all the answers

    What is the purpose of a capacitor in a circuit?

    <p>To block dc signals and allow ac signals to pass</p> Signup and view all the answers

    What is the dielectric constant of air?

    <p>1</p> Signup and view all the answers

    What is the term used to describe a capacitor that allows a varying signal to pass while blocking its average dc level?

    <p>Coupling capacitor</p> Signup and view all the answers

    What is the purpose of a capacitor in a circuit, as shown in Figure 8.80A?

    <p>To suppress signals on the dc supply voltages</p> Signup and view all the answers

    What is the equivalent of a capacitor at high frequencies?

    <p>A short circuit</p> Signup and view all the answers

    What is a typical feature of signal generators?

    <p>Provision for precise control of amplitude using an attenuator</p> Signup and view all the answers

    What is the primary application of capacitors in electronic circuits?

    <p>Bypass and coupling</p> Signup and view all the answers

    What is the formula for capacitance of a simple parallel-plate capacitor?

    <p>C = 8.85×10^−14 εA/d</p> Signup and view all the answers

    What is the term used to describe varying the output amplitude of a signal generator in time?

    <p>Amplitude Modulation</p> Signup and view all the answers

    What is the primary component of a frequency synthesizer that generates sinewaves of precise frequencies?

    <p>Quartz-crystal oscillator</p> Signup and view all the answers

    What is the range of amplitude of the programmable SG384 signal generator from Stanford Research Systems?

    <p>-110 dBm to +16.5 dBm</p> Signup and view all the answers

    What is the purpose of a sweep generator in testing circuits?

    <p>To test circuits whose properties vary with frequency</p> Signup and view all the answers

    What is the frequency range of the programmable SG384 signal generator from Stanford Research Systems?

    <p>1 μHz to 4 GHz</p> Signup and view all the answers

    What is a common feature of modern signal generators and test instruments?

    <p>Programmability from a computer or digital instrument</p> Signup and view all the answers

    What is the purpose of an attenuator in a signal generator?

    <p>To provide precise control of the output amplitude</p> Signup and view all the answers

    What is a common material used for the dielectric in capacitors?

    <p>Polycarbonate</p> Signup and view all the answers

    Where are tantalum capacitors typically used?

    <p>Where greater capacitance is needed</p> Signup and view all the answers

    What is the purpose of electrolytic capacitors?

    <p>To filter power supplies</p> Signup and view all the answers

    Which type of capacitor is often used in demanding applications?

    <p>Polycarbonate capacitors</p> Signup and view all the answers

    What is the general configuration of a capacitor?

    <p>A plate of conductive material on a thin insulating material</p> Signup and view all the answers

    What is the unit of capacitance, in which you usually deal with?

    <p>Microfarads (μF)</p> Signup and view all the answers

    What happens to the voltage across a capacitor when a current flows through it?

    <p>It changes</p> Signup and view all the answers

    What is the energy stored in a charged capacitor?

    <p>UC = 1/2CV^2</p> Signup and view all the answers

    What is the rate of flow of energy into a capacitor?

    <p>V I</p> Signup and view all the answers

    What is the purpose of a capacitor in a circuit?

    <p>To store energy</p> Signup and view all the answers

    What happens to the voltage across a capacitor when you charge it up?

    <p>It increases linearly</p> Signup and view all the answers

    What is the relationship between the current flowing through a capacitor and the voltage across it?

    <p>I = C dV/dt</p> Signup and view all the answers

    What is the effect of omitting bypass capacitors from a circuit?

    <p>It can cause the circuit to malfunction</p> Signup and view all the answers

    What is the purpose of a capacitor in a circuit, besides storing energy?

    <p>All of the above</p> Signup and view all the answers

    What is the unit of capacitance that is commonly used in electronic circuits?

    <p>Picofarads (pF)</p> Signup and view all the answers

    What is the formula for the total capacitance of several capacitors connected in parallel?

    <p>Ctotal = C1 + C2 + C3 + ...</p> Signup and view all the answers

    What is the formula for the total capacitance of two capacitors connected in series?

    <p>Ctotal = C1C2 / (C1 + C2)</p> Signup and view all the answers

    What is the characteristic of the current that flows in a capacitor during charging?

    <p>It is proportional to the rate of change of voltage</p> Signup and view all the answers

    What happens to the power associated with capacitive current?

    <p>It is stored as energy in the capacitor's internal electric field</p> Signup and view all the answers

    What is the approach to dealing with AC circuits in the time domain?

    <p>Talk about V and I versus time</p> Signup and view all the answers

    What is the feature of capacitors that allows them to store energy?

    <p>Their internal electric field</p> Signup and view all the answers

    What is the difference between capacitive current and resistive current?

    <p>Capacitive current is proportional to the rate of change of voltage, while resistive current is proportional to voltage</p> Signup and view all the answers

    What is the purpose of studying RC circuits?

    <p>To understand the behavior of AC circuits in the time domain</p> Signup and view all the answers

    What is the role of the first buffer in the circuit shown in Figure 1.37?

    <p>To provide a replica of the input signal with low source resistance</p> Signup and view all the answers

    What determines the delay in the output pulse in the circuit shown in Figure 1.37?

    <p>The time constant of the RC circuit</p> Signup and view all the answers

    What is the purpose of the RC circuit in Figure 1.37?

    <p>To produce a delayed pulse</p> Signup and view all the answers

    What happens to the output of the RC circuit 10 μs after the input transitions?

    <p>It reaches 50% of the input voltage</p> Signup and view all the answers

    What is the function of the output buffer in the circuit shown in Figure 1.37?

    <p>To switch the output HIGH or LOW depending on the input</p> Signup and view all the answers

    Why is the Thevenin equivalent useful in analyzing RC circuits?

    <p>It allows us to simplify complex circuits</p> Signup and view all the answers

    What is the main advantage of using the Thevenin equivalent in analyzing RC circuits?

    <p>It reduces the complexity of the circuit</p> Signup and view all the answers

    What is the relationship between the time constant of the RC circuit and the delay in the output pulse?

    <p>The time constant is directly proportional to the delay</p> Signup and view all the answers

    What is the product RC referred to as in the context of RC circuits?

    <p>Time constant</p> Signup and view all the answers

    What is the shape of the discharge curve of a capacitor in an RC circuit?

    <p>Exponential</p> Signup and view all the answers

    What is the equation for the voltage across a capacitor in an RC circuit during charging?

    <p>V = Vf(1 - e^(-t/RC))</p> Signup and view all the answers

    What is the time required for a capacitor to reach a voltage V on the way to the final voltage Vf?

    <p>t = RC loge(Vf / (Vf - V))</p> Signup and view all the answers

    What is the effect of changing the battery voltage to a new value in an RC circuit?

    <p>The capacitor voltage decays to the new value</p> Signup and view all the answers

    What is the rule of thumb for the time required for a capacitor to charge or discharge to within 1% of its final value?

    <p>5RC</p> Signup and view all the answers

    What is the waveform of the output voltage across a capacitor when driven by a square wave input through a resistor?

    <p>Exponential</p> Signup and view all the answers

    What is the function of the RC circuit in terms of the input voltage?

    <p>Averager</p> Signup and view all the answers

    What is the equation for the rise time of an RC circuit?

    <p>t = 2.2RC</p> Signup and view all the answers

    What is the purpose of the RC circuit in terms of the frequency domain?

    <p>To filter out high frequencies</p> Signup and view all the answers

    What is the primary function of the comparator in the 'One Minute of Power' circuit?

    <p>To drive the output to either V+ or ground</p> Signup and view all the answers

    What is the purpose of the voltage divider R3R4 in the 'One Minute of Power' circuit?

    <p>To hold the (-) input at a fixed reference voltage</p> Signup and view all the answers

    What happens to the comparator's output when the START button is pushed in the 'One Minute of Power' circuit?

    <p>It switches to +5V</p> Signup and view all the answers

    What is the time constant of the RC circuit in the 'One Minute of Power' circuit?

    <p>10 ms</p> Signup and view all the answers

    What is the maximum current that the comparator can drive in the 'One Minute of Power' circuit?

    <p>20 mA</p> Signup and view all the answers

    What is the purpose of the capacitor C1 in the 'One Minute of Power' circuit?

    <p>To store energy and control the timing of the circuit</p> Signup and view all the answers

    What is the output of the comparator in the 'One Minute of Power' circuit when the input is more positive than the reference voltage?

    <p>V+</p> Signup and view all the answers

    What is the duration of the output of the 'One Minute of Power' circuit?

    <p>1 minute</p> Signup and view all the answers

    What is the time constant of the capacitor discharging exponentially toward ground?

    <p>1 minute</p> Signup and view all the answers

    What is the purpose of adding a resistor R1 in the circuit of Figure 1.38?

    <p>To limit the peak current while charging the capacitor</p> Signup and view all the answers

    What is the term used to describe the process of reinforcing the switching in a comparator output?

    <p>Positive feedback</p> Signup and view all the answers

    What is the benefit of using a solid-state relay (SSR) to switch on and off industrial machinery?

    <p>It is electrically isolated from the input circuit</p> Signup and view all the answers

    What is the effect of omitting R1 in the circuit of Figure 1.38?

    <p>There will be a large transient current when the capacitor is initially connected</p> Signup and view all the answers

    What is the purpose of bypassing the dc supply with one or more capacitors?

    <p>To reduce the noise in the dc supply</p> Signup and view all the answers

    How long does the output of the timer circuit remain at +5 V after the button is pushed?

    <p>1 minute</p> Signup and view all the answers

    What is the effect of the comparator output bouncing around a bit when the (+) input crosses the reference voltage?

    <p>It causes the output to switch rapidly</p> Signup and view all the answers

    What is the advantage of using an electromechanical relay over a solid-state relay?

    <p>It is not commonly used in industrial applications</p> Signup and view all the answers

    What is the purpose of connecting a resistor in series with an LED when using it as a load in the timer circuit?

    <p>To reduce the current through the LED</p> Signup and view all the answers

    What is the cause of the signals shown in Figure 1.45?

    <p>All of the above</p> Signup and view all the answers

    What is the effect of unintentional capacitive coupling on a signal line?

    <p>It causes a differentiated signal to appear on the signal line</p> Signup and view all the answers

    What is the solution to unintentional capacitive coupling on a signal line?

    <p>Add a resistor termination to the signal line</p> Signup and view all the answers

    What is the effect of a broken connection in a circuit on the signal?

    <p>It differentiates the signal</p> Signup and view all the answers

    What is the cause of the signal shown in the second case of Figure 1.45?

    <p>A broken connection in the circuit</p> Signup and view all the answers

    What is the purpose of identifying unintentional capacitive coupling in a circuit?

    <p>To find and eliminate the problem</p> Signup and view all the answers

    What is the purpose of adding a small resistor from the low side of the capacitor to ground in a differentiator circuit?

    <p>To act as a current-sensing resistor</p> Signup and view all the answers

    What is the output of a differentiator circuit proportional to?

    <p>The derivative of the input signal</p> Signup and view all the answers

    What is the effect of making the product RC small in a differentiator circuit?

    <p>It ensures that the output is proportional to the derivative of the input signal</p> Signup and view all the answers

    What is the purpose of using a buffer in a differentiator circuit?

    <p>To convert the spikes to short square-topped pulses</p> Signup and view all the answers

    What is the effect of driving a differentiator circuit with a square wave?

    <p>It produces spikes at the transitions of the input signal</p> Signup and view all the answers

    What is the advantage of using a differentiator circuit in digital circuitry?

    <p>It detects leading edges and trailing edges in pulse signals</p> Signup and view all the answers

    What is the condition for a differentiator circuit to be a perfect mathematical differentiator?

    <p>The voltage across the capacitor is equal to the input voltage</p> Signup and view all the answers

    Why is the negative spike small in a leading-edge detector circuit?

    <p>Because of the diode in the buffer</p> Signup and view all the answers

    What is the typical value of the resistor used in high-speed circuits?

    <p>50 Ω</p> Signup and view all the answers

    What is the purpose of using a capacitor in a differentiator circuit?

    <p>To generate a current proportional to the derivative of the input signal</p> Signup and view all the answers

    Study Notes

    The Development of Electronics

    • The field of electronics has been a great success story of the 20th century, evolving from crude spark-gap transmitters and "cat's-whisker" detectors to sophisticated vacuum-tube electronics and eventually solid-state electronics.
    • The first half of the 20th century saw the development of vacuum-tube electronics, which found applications in communications, navigation, instrumentation, control, and computation.
    • The latter half of the 20th century brought significant advances in solid-state electronics, first with discrete transistors and later with integrated circuits (ICs), leading to compact and inexpensive consumer products.

    Advances in Electronics

    • Modern electronics have enabled the creation of compact and inexpensive consumer products that contain millions of transistors in VLSI (very large-scale integration) chips.
    • These products can process sounds, images, and data, and permit wireless networking and access to the Internet.
    • The cost of an electronic microcircuit decreases significantly as the manufacturing process is perfected, often to a fraction of its initial cost.

    The Focus of this Book

    • This book aims to convey the excitement and know-how of electronics, starting with the basics of voltage, current, power, and electronic components.
    • The book will cover the laws, rules of thumb, and tricks that constitute the art of electronics.
    • The first chapter will focus on the foundations of electronics, which may require some abstraction and dependence on visualizing instruments like oscilloscopes and voltmeters.

    Voltage and Current

    • Voltage (V) is the energy required to move a unit of positive charge from a more negative point to a more positive point in a circuit.
    • Voltage is also known as potential difference or electromotive force (EMF).
    • The unit of voltage is the volt (V), with common expressions in volts (V), kilovolts (kV), millivolts (mV), or microvolts (μV).
    • A joule (J) of work is done in moving a coulomb (C) of charge through a potential difference of 1 V.
    • Current (I) is the rate of flow of electric charge past a point.
    • The unit of current is the ampere (A), with common expressions in amperes (A), milliamperes (mA), microamperes (μA), nanoamperes (nA), or picoamperes (pA).
    • A current of 1 A equals a flow of 1 C of charge per second.
    • By convention, current flows from a more positive point to a more negative point in a circuit.
    • Important: voltage is applied across two points in a circuit, and current flows through a device or connection in a circuit.

    Voltage and Current Relationships

    • Voltages are generated by doing work on charges in devices such as batteries, generators, and solar cells.
    • Currents are obtained by placing voltages across things.
    • The oscilloscope is a useful tool for visualizing voltage and current in a circuit as a function of time.

    Rules for Voltage and Current

    • The sum of the currents into a point in a circuit equals the sum of the currents out (conservation of charge), also known as Kirchhoff's current law (KCL).
    • In a series circuit, the current is the same everywhere.
    • Things connected in parallel have the same voltage across them, and the sum of the "voltage drops" from one point to another via any path is equal to the sum via any other route.
    • The power (energy per unit time) consumed by a circuit device is P = V I, where P is in watts (W), V is in volts, and I is in amps.

    Resistor Types

    • Various types of resistors are available, including wirewound ceramic power resistors, wirewound power resistors, carbon composition resistors, surface-mount thick-film resistors, and surface-mount resistor arrays.

    Relationship between Voltage and Current: Resistors

    • The current through a metallic conductor (or other partially conducting material) is proportional to the voltage across it.
    • This is an interesting fact, but not a universal law for all objects, e.g., the current through a neon bulb is a highly nonlinear function of the applied voltage.

    Resistors

    • A resistor is made out of some conducting stuff (carbon, metal, or carbon film) with a wire or contacts at each end.
    • It is characterized by its resistance (R = V/I), measured in ohms (Ω) for V in volts and I in amps.
    • Ohm's law states that R is constant for a given resistor, but it can vary with temperature, voltage, time, and humidity.
    • Resistors are used to convert a voltage to a current, and vice versa.

    Types of Resistors

    • Metal-oxide film, metal film, or carbon film resistors are the most frequently used type.
    • They come in values from 1 ohm (1 Ω) to about 10 megohms (10 MΩ).
    • They are also characterized by power rating, physical size, tolerance, temperature coefficient, noise, and voltage coefficient.

    Resistors in Series and Parallel

    • The resistance of two resistors in series (R1 and R2) is R = R1 + R2.
    • The resistance of two resistors in parallel (R1 and R2) is R = R1R2 / (R1 + R2) or R = 1 / (1/R1 + 1/R2).

    Power in Resistors

    • The power dissipated by a resistor (or any other device) is P = IV.
    • Using Ohm's law, P can be expressed as P = I²R or P = V² / R.

    Voltage Dividers

    • A voltage divider is a circuit fragment that accepts an input voltage and produces a corresponding output voltage.
    • The transfer function H is the ratio of output voltage to input voltage.
    • With only resistors, we can already look at a voltage divider, which can be used as a "de-amplifier".

    Voltage Dividers

    • A voltage divider is a circuit that produces a predictable fraction of the input voltage as the output voltage.
    • The simplest voltage divider consists of two resistors (R1 and R2) connected in series, with the input voltage (Vin) applied across them.
    • The output voltage (Vout) is the voltage across R2, which is smaller than the input voltage.

    How Voltage Dividers Work

    • The current (I) through the circuit is the same everywhere, assuming no load on the output.
    • The current is calculated by: I = Vin / (R1 + R2)
    • The output voltage is calculated by: Vout = IR2 = (R2 / (R1 + R2)) * Vin

    Characteristics of Voltage Dividers

    • The output voltage is always less than or equal to the input voltage.
    • Voltage dividers can be used to generate a particular voltage from a larger fixed or varying voltage.

    Adjustable Voltage Dividers

    • An adjustable voltage divider can be made using a fixed and variable resistor, or a potentiometer.
    • The output voltage can be adjusted by changing the value of the variable resistor.

    Applications of Voltage Dividers

    • Voltage dividers are often used in circuits to generate a particular voltage from a larger fixed or varying voltage.
    • They can be used as "volume controls" to adjust the voltage level of a signal.
    • They can also be used to represent the output of an amplifier and the input of a following stage.

    Other Types of Voltage Dividers

    • Some contemporary circuits use a long series chain of equal-value resistors with electronic switches to choose the output voltage.
    • This design allows for electrical adjustment of the voltage ratio.

    Voltage Sources

    • A perfect voltage source is a two-terminal device that maintains a fixed voltage drop across its terminals, regardless of load resistance.
    • A real voltage source has a limited maximum current it can supply and behaves like a perfect voltage source with a small resistance in series.
    • A voltage source "likes" an open-circuit load and "hates" a short-circuit load.
    • The symbols used to indicate a voltage source are shown in Figure 1.9.
    • A real-life approximation to a voltage source is a battery.
    • A standard 9-volt alkaline battery behaves approximately like a perfect 9-volt voltage source in series with a 3 Ω resistor.
    • A battery can provide a maximum current when shorted, but this will drain the battery quickly.

    Current Sources

    • A perfect current source is a two-terminal device that maintains a constant current through the external circuit, regardless of load resistance or applied voltage.
    • A real current source has a limit to the voltage it can provide, called the output-voltage compliance, and does not provide absolutely constant output current.
    • A current source "likes" a short-circuit load and "hates" an open-circuit load.
    • The symbols used to indicate a current source are shown in Figure 1.10.

    Characteristics of Batteries

    • A standard D-size flashlight cell has a terminal voltage of 1.5 V, an equivalent series resistance of about 0.25 Ω, and a total energy capacity of about 10,000 watt-seconds.
    • The characteristics of a battery gradually deteriorate with use, affecting its voltage and internal series resistance.

    Thevenin Equivalent Circuit

    • The Thevenin equivalent circuit is represented in Figure 1.11.
    • It is a major topic of Chapter 9.

    Thevenin Equivalent Circuit

    • Thevenin's theorem states that any two-terminal network of resistors and voltage sources can be equivalent to a single resistor R in series with a single voltage source V.
    • This means that a complex circuit can be simplified into a single resistor and voltage source.
    • To find the Thevenin equivalent circuit, you need to calculate the open-circuit voltage (VTh) and the short-circuit current (RTh).
    • The formula to calculate RTh is RTh = V (open circuit) / I (short circuit).

    Example of Thevenin Equivalent Circuit

    • The voltage divider circuit can be simplified into a Thevenin equivalent circuit.
    • The open-circuit voltage is V = Vin * R2 / (R1 + R2).
    • The short-circuit current is Vin / R1.
    • The Thevenin equivalent circuit is a voltage source VTh = Vin * R2 / (R1 + R2) in series with a resistor RTh = R1 * R2 / (R1 + R2).

    Multimeters

    • Multimeters are instruments used to measure voltage, current, and resistance.
    • There are two types of multimeters: analog multimeters (VOM) and digital multimeters (DMM).
    • Analog multimeters use a meter movement that measures current, and they respond slowly to changing voltages.
    • Digital multimeters use electronic amplification and have a high input resistance, making them ideal for measuring voltage, current, and resistance.
    • Multimeters can have several voltage and current ranges, and they can also measure resistance.

    Loading Effects

    • Loading effects occur when a load resistor is attached to a circuit, causing the output voltage to drop.
    • The Thevenin equivalent circuit can be used to calculate the output voltage and current with a load resistor.
    • To minimize loading effects, the load resistance should be much greater than the source resistance.
    • The concept of equivalent internal resistance applies to all sources, not just batteries and voltage dividers.

    Power Transfer

    • The maximum power is transferred to the load when the load resistance is equal to the source resistance.
    • If the load resistance is too low or too high, the power transferred to the load is zero.

    Important Notes

    • Circuits are usually designed so that the load resistance is much greater than the source resistance.
    • Anthropomorphizing, or attributing human-like qualities to circuits, is a common pitfall in engineering and science.

    Small-signal Resistance

    • Small-signal resistance (incremental resistance or dynamic resistance) is the ratio of a small change in applied voltage to the resulting change in current, ΔV/ΔI (or dV/dI).
    • It has the units of resistance (ohms) and is used in many calculations.
    • Small-signal resistance substitutes for resistance in devices where I is not proportional to V.

    Zener Diodes

    • Zener diodes are used to create a constant voltage inside a circuit.
    • They are provided with a roughly constant current derived from a higher voltage within the circuit.
    • The I–V curve of a zener diode shows a narrow range of voltages corresponding to a range of applied currents.
    • Dynamic resistance is specified for a zener diode at a certain current, e.g., 10 Ω at 10 mA and 5 V.
    • A 10% change in applied current results in a change in voltage of ΔV = RdynΔI.
    • Zener diodes have good voltage-regulating ability, e.g., a 10% change in current results in a 0.2% change in voltage.

    Zener Regulator Circuit

    • The zener current is typically obtained through a resistor from a higher voltage available in the circuit.
    • The circuit behaves like a voltage divider, with the zener replaced by a resistor equal to its dynamic resistance at the operating current.
    • The output-voltage regulation can be estimated using the dynamic resistance of the zener diode.

    Characteristics of Zener Diodes

    • Dynamic resistance of a zener diode varies roughly in inverse proportion to current.
    • Low-voltage zener diodes (e.g., 3.3 V) behave poorly in terms of constancy of voltage versus current.
    • Two-terminal voltage references (ICs) are designed to substitute for zener diodes, with superior performance (e.g., much lower dynamic resistance and excellent temperature stability).

    Temperature-Sensing Circuit

    • A temperature-sensing circuit can be created using a voltage divider, a comparator, and an LED to indicate when the room temperature exceeds 30°C (86°F).

    Components and Their Functions

    • R4: temperature-sensing device that decreases in resistance by about 4%/°C, with a resistance of 10kΩ at 25°C.
    • Comparator: a device that switches its output according to the relative voltages at its two input terminals.
    • LED: behaves electrically like a 1.6 V zener diode, and lights up when current is flowing.

    Voltage Divider and Comparator

    • The voltage divider (R3R4) has an output that is compared with the temperature-insensitive divider (R1R2).
    • When the temperature is above 30°C, the comparator output is pulled to ground.

    LED and Resistor

    • The LED is connected to the output of the comparator, with a series resistor (R5) sized to allow 5 mA of current when the comparator output is at ground.
    • R5 is calculated as 3.4 V/5 mA, or 680 Ω.

    Adjustable Setpoint and Hysteresis

    • The setpoint can be made adjustable by replacing R2 with a 5k pot in series with a 5k fixed resistor.
    • Adding hysteresis to the comparator is recommended to encourage decisive switching.

    Ratiometric Techniques

    • The circuit is insensitive to the exact power supply voltage because it compares ratios, making it a good design technique.
    • Ratiometric techniques will be seen again in later applications.

    Signals

    • Signals are voltages that change in time in a particular way, and are essential for understanding alternating-current (ac) circuits.

    Sinusoidal Signals

    • Sinusoidal signals are the most common type of signal, and are what you get out of a wall plug.
    • They are described by the equation: V = Asin(2πft) or V = Asin(2πft + φ), where A is the amplitude, f is the frequency in hertz, and φ is the phase.
    • The angular frequency ω is measured in radians per second, and is related to the frequency f by the equation: ω = 2πf.
    • Sinewaves are the solutions to certain linear differential equations that describe many phenomena in nature and the properties of linear circuits.
    • Linear circuits have the property that their output, when driven by the sum of two input signals, equals the sum of its individual outputs when driven by each input signal in turn.

    Properties of Sinewaves

    • A linear circuit driven by a sinewave always responds with a sinewave, although the phase and amplitude may be changed.
    • No other periodic signal can make this statement.
    • The frequency response of a circuit describes how it alters the amplitude of an applied sinewave as a function of frequency.
    • Sinewave frequencies can range from a few hertz to a few tens of megahertz, and higher frequencies can be generated with special techniques.

    Real-World Applications

    • A stereo amplifier, for instance, should be characterized by a "flat" frequency response over the range 20 Hz to 20 kHz.
    • Lower frequencies, down to 0.0001 Hz or lower, can be generated with carefully built circuits, if needed.
    • Higher frequencies, up to say 2000 MHz (2 GHz) and above, can be generated, but they require special transmission-line techniques.

    Signal Amplitudes and Decibels

    • Signal amplitude can be characterized by peak-to-peak amplitude (pp amplitude) and root-mean-square amplitude (rms amplitude)
    • For sinewaves, rms amplitude (Vrms) is related to amplitude (A) by Vrms = (1/√2)A = 0.707A
    • The nominal voltage across a wall socket in the US is 120 volts rms, 60 Hz, with an amplitude of 170 volts and a peak-to-peak amplitude of 339 volts

    Decibels

    • Decibels (dB) are used to compare the relative amplitudes of two signals
    • The ratio of two signals in decibels is defined as dB = 10log10(P2/P1), where P1 and P2 are the power in the two signals
    • For signals with the same waveform, dB = 20log10(A2/A1), where A1 and A2 are the signal amplitudes
    • Examples of decibel ratios:
      • +6 dB: a signal with twice the amplitude of another signal
      • +20 dB: a signal 10 times as large as another signal
      • -20 dB: a signal one-tenth as large as another signal
    • Decibels can be used as an absolute measure of amplitude by assuming a reference signal level and expressing other levels in decibels relative to it

    Other Signals

    Ramp

    • A ramp is a signal that rises (or falls) at a constant rate
    • It can be approximated by a finite ramp or a periodic ramp (sawtooth)

    Triangle

    • A triangle wave is a symmetrical ramp

    Noise

    • Noise is a catch-all phrase that usually applies to random noise of thermal origin
    • Noise voltages can be specified by their frequency spectrum (power per hertz) or by their amplitude distribution
    • Band-limited white Gaussian noise is a type of noise that has equal power per hertz in some band of frequencies and exhibits a Gaussian distribution of amplitudes

    Square Wave

    • A square wave is a signal that varies in time with a constant amplitude and frequency
    • It is characterized by amplitude and frequency (and perhaps phase)
    • The peak amplitude and the rms amplitude of a square wave are the same

    Pulses

    • A pulse is a signal that has a defined amplitude and pulse width
    • Pulses can have positive or negative polarity and can be positive-going or negative-going
    • The pulse repetition rate and duty cycle can be defined for a train of periodic pulses

    Steps and Spikes

    • Steps and spikes are signals that are used to describe what happens in a circuit
    • They can be used to describe a square wave or a sudden jump in voltage

    Logic Levels

    • Pulses and square waves are used in digital electronics to represent two possible states (HIGH and LOW)
    • Each digital logic family specifies legal HIGH and LOW states and an input decision threshold

    Signal Sources

    • Signal sources are essential for testing circuits and come in three types: signal generators, pulse generators, and function generators.
    • Signal generators:
      • Are sinewave oscillators with a wide range of frequency coverage.
      • Can modulate (vary) output amplitude or frequency.
      • Can be sweep generators, which repeatedly sweep output frequency over a range.
      • Often have digital frequency synthesizers as the signal source.
    • Pulse generators:
      • Make only pulses, but with adjustable parameters such as pulse width, repetition rate, amplitude, polarity, and rise time.
      • Can generate pulse pairs with settable spacing and repetition rate.
      • Often have logic-level outputs for easy connection to digital circuitry.
    • Function generators:
      • Are the most flexible signal sources.
      • Can generate sine, triangle, and square waves over a wide frequency range.
      • Can control amplitude and dc offset.
      • Often have provision for frequency sweeping, modulation, and pulse outputs.

    Capacitors and AC Circuits

    • Capacitors are essential components in AC circuits, used for waveform generation, filtering, and blocking and bypass applications.
    • Capacitors have two wires and the property Q = CV, where Q is the stored charge and C is the capacitance.
    • The capacitance of a parallel-plate capacitor is proportional to the area and inversely proportional to the spacing.

    Capacitors

    • A capacitor is a device that stores energy in its internal electric fields.
    • The energy stored in a capacitor is UC = 1/2 CV^2, where UC is the energy in joules, C is the capacitance in farads, and V is the voltage in volts.
    • Capacitors come in various shapes and sizes, including parallel-plate, cylindrical, and film capacitors.
    • Different types of capacitors have unique properties, such as ceramic, polyester, polycarbonate, polystyrene, polypropylene, Teflon, and glass dielectric.
    • Capacitors are used in various applications, including filtering, energy storage, and resonant circuits.

    Math and Capacitors

    • The derivative of the defining equation Q = CV is I = CdV/dt, which shows that the current is proportional to the rate of change of voltage.
    • The capacitance of a capacitor can be calculated using the formula C = 8.85 x 10^-14 εA/d, where ε is the dielectric constant, A is the plate area, and d is the spacing.

    Capacitors in Parallel and Series

    • The capacitance of several capacitors in parallel is the sum of their individual capacitances.
    • The formula for capacitance in parallel is: Ctotal = C1 + C2 + C3 + …

    Capacitors in Series

    • The formula for capacitance in series is: Ctotal = 1 / (1/C1 + 1/C2 + 1/C3 + …)
    • For two capacitors in series, the formula is: Ctotal = (C1C2) / (C1 + C2)

    Capacitors Charging and Discharging

    • The current that flows in a capacitor during charging is not proportional to voltage, but rather to the rate of change of voltage.
    • The power associated with capacitive current is not turned into heat, but is stored as energy in the capacitor's internal electric field.
    • The energy stored in a capacitor is returned when it is discharged.

    RC Circuits: V and I versus Time

    • When dealing with AC circuits, there are two approaches: talking about V and I versus time, or amplitude versus signal frequency.
    • The simplest RC circuit is described by the equation: CdV/dt = I = -V/R
    • The solution to this equation is: V = Ae^(-t/RC)
    • The product RC is called the time constant of the circuit.

    Time Constant

    • The time constant is in seconds, for R in ohms and C in farads.
    • A microfarad across 1.0k has a time constant of 1 ms.

    RC Charging Circuit

    • The equation for the RC charging circuit is: I = CdV/dt = Vf - Vout / R
    • The solution to this equation is: Vout = Vf + Ae^(-t/RC)
    • The constant A is determined by initial conditions, such as V = 0 at t = 0.
    • The final equation is: Vout = Vf(1 - e^(-t/RC))

    Decay to Equilibrium

    • Eventually, V reaches Vf, which is the final voltage.
    • The "5RC rule of thumb" states that a capacitor charges or decays to within 1% of its final value in five time constants.

    Simplification by Thevenin Equivalents

    • Thevenin equivalents can be used to simplify more complicated circuits.
    • By using the Thevenin equivalent of a voltage divider, the output V(t) can be found.

    Circuit Example: Time-Delay Circuit

    • The circuit uses an RC and a pair of CMOS buffers to produce a delayed digital waveform.
    • The first buffer provides a replica of the input signal, with low source resistance, to prevent input loading by the RC.
    • The RC output has the characteristic decays and causes the output buffer to switch 10 μs after the input transitions.

    One Minute of Power Circuit

    • The circuit uses a comparator, powered from a positive dc voltage, to drive its output either to V+ or to ground.
    • The comparator has three important properties: it doesn't draw current from its inputs, it drives loads up to 20mA, and its output is either HIGH (at V+) or LOW (ground).
    • The circuit uses a voltage divider (R3R4) to set a reference voltage, which is 37% of the supply voltage.
    • When the START button is pushed, the capacitor C1 charges quickly, causing the comparator's output to switch to +5V.
    • After the button is released, the capacitor discharges exponentially, with a time constant of τ = R2C1, which is set to 1 minute.

    Applications of the One Minute of Power Circuit

    • The output can be used to drive an LED, a piezo beeper, or an electromechanical relay to control a load.
    • The relay provides electrical isolation between the timing circuit and the load.
    • The circuit can be used to make a self-stopping flashlight key fob, a noise-making device, or an electromechanical relay to control a load.

    Details of the Circuit

    • The addition of R1 limits the peak current to 5mA when charging the capacitor.
    • The comparator output may bounce around due to electrical noise, which can be fixed by adding hysteresis (positive feedback) to the circuit.
    • It's a good idea to bypass the dc supply with a capacitor to prevent noise and voltage droop.

    Differentiators

    • A differentiator circuit produces an output proportional to the rate of change of the input waveform (dVin/dt).
    • The ideal differentiator circuit is impractical, but a simple RC circuit can approximate the function.
    • The output of the differentiator is proportional to the input waveform's rate of change, but with a small error due to the resistor's presence.

    Applications of Differentiators

    • Differentiators can detect leading edges and trailing edges in pulse signals.
    • They can be used in digital circuitry to generate short pulses in response to input transitions.

    Unintentional Differentiators

    • Capacitive coupling between signals can cause unintentional differentiators, which can be recognized by their output waveforms.
    • Broken connections can also cause unintentional differentiators, which can be diagnosed by recognizing the characteristic output waveforms.

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    This quiz covers the introduction to the field of electronics, its history, and development from vacuum-tube to solid-state electronics.

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