by Earl Boysen
Summary
This chapter introduced the following concepts and calculations related to power supplies:
The effects of diodes on AC signals
Methods of rectifying an AC signal
Half-wave and full-wave rectifier circuit designs
The calculations you can use to determine component values for half-wave and full-wave rectifier power supply circuits
Self-Test
These questions test your understanding of the information presented in this chapter. Use a separate sheet of paper for your diagrams or calculations. Compare your answers with the answers provided following the test.
In questions 1 through 5, draw the output waveform of each circuit. The input is given in each case.
1. See Figure 11.51.
Figure 11.51
2. See Figure 11.52.
Figure 11.52
3. See Figure 11.53.
Figure 11.53
4. See Figure 11.54.
Figure 11.54
5. See Figure 11.55.
Figure 11.55
6. In the circuit shown in Figure 11.56, 100 Vrms at 60 Hz appears at the secondary coil of the transformer; 28 volts DC with as little AC ripple as possible is required across the 220-ohm load. Find R1, C1, and C2. Find the approximate AC ripple.
Figure 11.56
Answers to Self-Test
If your answers do not agree with those given here, review the problems indicated in parentheses.
1. See Figure 11.57.
Figure 11.57
(problems 1–5)
2. See Figure 11.58.
Figure 11.58
(problem 2)
3. See Figure 11.59.
Figure 11.59
(problem 11)
4. See Figure 11.60.
Figure 11.60
(problem 13)
5. See Figure 11.61.
Figure 11.61
(problems 15–18)
6. R1 = 833 ohms, C1 = 79 μF: let XC2 = 22 ohms and then C2 = 60 μF
(problems 26–30)
Chapter 12
Conclusion and Final Self-Test
In this book, you have discovered basic concepts and formulas that provide a foundation for your studies in modern electronics, whether you become a dedicated hobbyist or study electrical or electronics engineering.
Conclusion
Having read this book, you should now know enough to read intermediate-level electronics books and articles intelligently, to build electronics circuits and projects, and to pursue electronics to whatever depth and for whatever reason you want. Specifically, you should now be able to do the following:
Recognize all the important, discrete electronics components in a schematic diagram.
Understand how circuits that use discrete components work.
Calculate the component values needed for circuits to function efficiently.
Design simple circuits.
Build simple circuits and electronics projects.
To see how much you have learned, you may want to take the final self-test at the end of this chapter. It tests your comprehension of the concepts and formulas presented throughout this book.
When you complete the following self-test and feel confident that you have mastered the information in this book, refer to Appendix E, “Supplemental Resources,” for additional resources for further learning, including the following:
Books such as The Art of Electronics by Paul Horowitz and Winfield Hill (New York: Cambridge University Press, 1989) provide a great next step in further electronics study.
Magazines such as Everyday Practical Electronics offer interesting projects in each issue.
You can browse websites for electronics project ideas.For example, Earl Boysen's website, www.buildinggadgets.com, provides tips, ideas, and links to a variety of great online resources.
Note For those interested in more serious study, you should be aware that there is a difference between the path you take to become an electrician (or technician) and an electrical (or electronics) engineer. Training for electronics technicians is available in military trade schools, public and private vocational schools, and in many high schools. Engineers are required to understand the mathematical details in more depth and must take at least a 4-year curriculum at an accredited college or university.
Whatever your goal, you can feel confident that this book has given you a solid grounding for your future studies. Wherever you go in electronics, good luck!
Final Self-Test
This final test allows you to assess your overall knowledge of electronics. Answers and review references follow the test. Use a separate sheet of paper for your calculations and drawings.
1. If R = 1 MΩ and I = 2 μA, find the voltage. _____
2. If V = 5 volts and R = 10 kV, find the current. _____
3. If V = 28 volts and I = 4 amperes, find the resistance. _____
4. If 330 ohms and 220 ohms are connected in parallel, find the equivalent resistance. _____
5. If V = 28 volts and I = 5 mA, find the power. _____
6. If the current through a 220-ohm resistor is 30.2 mA, what is the power dissipated by the resistor? _____
7. If the power rating of a 1000-ohm resistor is 0.5 watts, what is the maximum current that can safely flow through the resistor? _____
8. If a 10-ohm resistor is in series with a 32-ohm resistor, and the combination is across a 12-volt supply, what is the voltage drop across each resistor, and what will the two voltage drops add up to? _____
9. A current of 1 ampere splits between 6-ohm and 12-ohm resistors in parallel. Find the current through each. _____
10. A current of 273 mA splits between 330-ohm and 660-ohm resistors in parallel. Find the current through each resistor. _____
11. If R = 10 kV and C = 1 μF, find the time constant. _____
12. If R = 1 MV and C = 250 μF, find the time constant. _____
13. Three capacitors of 1 μF, 2 μF, and 3 μF are connected in parallel. Find the total capacitance. _____
14. Three capacitors of 100 μF, 220 μF, and 220 μF are connected in series. Find the total capacitance. _____
15. Three capacitors of 22 pF, 22 pF, and 33 pF are connected in series. Find the total capacitance. _____
16. What is the knee voltage for a germanium diode? _____
17. What is the knee voltage for a silicon diode? _____
18. In the circuit shown in Figure 12.1, VS = 5 volts and R = 1 kV. Find the current through the diode, ID. _____
19. For the circuit shown in Figure 12.1, V = 12 volts and R = 100 ohms. Find ID. _____
20. For the circuit shown in Figure 12.2, VS = 100 volts, R1 = 7.2 kV, R2 = 4 kV, and VZ = 28 volts. Find the current through the zener diode, IZ. _____
21. For the circuit in Figure 12.2, VS = 10 volts, R1 = 1 kV, R2 = 10 kV, and VZ = 6.3 volts. Find IZ. _____
22. Using the circuit shown in Figure 12.3, find the DC collector voltage, VC, if VS = 28 volts, β = 10, RB = 200 kV, and RC = 10 kV. _____
23. Again, using the circuit shown in Figure 12.3, find RB if VS = 12 volts, β = 250, RC = 2.2 kV, and VC = 6 volts. _____
24. Using the circuit shown in Figure 12.3, find β if VS = 10 volts, RB = 100 kV, RC = 1 kV, and VC = 5 volts. _____
25. What are the three terminals for a JFET called, and which one controls the operation of the JFET? _____
26. Using the circuit shown in Figure 12.4, find the value of RB required to turn the transistor ON if VS = 14 volts, RC = 10 kV, and β = 50. _____
27. Again, using the circuit shown in Figure 12.4, find the value of RB required to turn the transistor ON if VS = 5 volts, RC = 4.7 kV, and β = 100. _____
28. Using the circuit shown in Figure 12.5,find the values of R1, R2, and R3 that can enable the switch to turn Q2 ON and OFF, if VS = 10 volts, β1 = 50, β2 = 20, and R4 = 2.2 kV. _____
29. Again, using the circuit shown in Figure 12.5, find the values of R1, R2, and R3 that can enable the switch to tur
n Q2 ON and OFF if VS = 28 volts, β1 = 30, β2 = 10, and R4 = 220 V. _____
30. An N-channel JFET has a drain saturation current of IDSS = 14 mA. If a 28-volt drain supply is used, calculate the drain resistance, RD. _____
31. Draw one cycle of a sine wave. _____
32. Mark in Vpp, Vrms, and the period of the waveform on your drawing for question 31. _____
33. If Vpp = 10 volts, find Vrms. _____
34. If Vrms = 120 volts, find Vpp. _____
35. If the frequency of a sine wave is 14.5 kHz, what is the period of the waveform? _____
36. Find the reactance XC for a 200 μF capacitor when the frequency is 60 Hz. _____
37. Find the value of the capacitance that gives a 50-ohm reactance at a frequency of 10 kHz. _____
38. Find the inductive reactance XL for a 10-mH inductor when the frequency is 440 Hz. _____
39. Find the value of the inductance that has 100 ohms reactance when the frequency is 1 kHz. _____
40. Find the series and parallel resonant frequency of a 0.1 μF capacitor and a 4-mH inductor that has negligible internal resistance. _____
41. Using the circuit shown in Figure 12.6, find XC, Z, Vout, I, tan θ, and θ, if Vin = 10 Vpp, f = 1 kHz, C = 0.1 μF, and R = 1600 ohms. _____
42. Again, using the circuit shown in Figure 12.6, find XC, Z, Vout, I, tan θ, and θ, if Vin = 120 Vrms, f = 60 Hz, C = 0.33 μF, and R = 6 kV. _____
43. Using the circuit shown in Figure 12.7, find XC, AC Vout, and DC Vout, if Vin = 1 Vpp AC, riding on a 5-volt DC level; f = 10 kHz; R1 = 10 kV; R2 = 10 kV; and C = 0.2 μF. _____
44. Again, using the circuit shown in Figure 12.7, find XC, AC Vout, and DC Vout, if Vin = 0.5 Vpp AC, riding on a 10-volt DC level; f = 120 Hz; R1 = 80 ohms; R2 = 20 ohms; and C = 1000 μF. _____
45. In the circuit shown in Figure 12.8, Vin = 10 Vpp AC, riding on a 5-volt DC level; f = 1 kHz; L = 10 mH; r = 9 ohms; and R = 54 ohms. Find AC Vout, DC Vout, XL, Z, tan θ, and θ. _____
46. In the circuit shown in Figure 12.9, L = 1 mH, C = 0.1 μF, and R = 10 ohms. Find fr, XL, XC, Z, Q, and the bandwidth. _____
47. In the circuit shown in Figure 12.10, L = 10 mH, C = 0.02 μF, and r = 7 ohms.Find fr, XL, XC, Z, Q, and the bandwidth. _____
48. If the voltage across the resonant circuit of question 47 is at a peak value of 8 volts at the resonant frequency, what is the voltage at the half-power points and what are the half-power frequencies? _____
49. Using the amplifier circuit shown in Figure 12.11, find the values of R1, R2, and RE that can provide the amplifier with a voltage gain of 10. Use VS = 28 volts, RC = 1 kV, and β = 100. _____
50. Again, using the circuit shown in Figure 12.11, find the values of R1, R2, and RE that can provide the amplifier a voltage gain of 20. Use VS = 10 volts, RC = 2.2 kV, and β = 50. _____
51. Using the circuit shown in Figure 12.11, how would you modify the amplifier in question 50 to obtain a maximum gain? Assume that the lowest frequency it has to pass is 50 Hz. _____
52. Using the JFET amplifier circuit shown in problem 42 of Chapter 8, “Transistor Amplifiers,” with a bias point of VGS = −2.8 volts, a drain current of ID = 2.7 mA, and VDS = 12 volts, find the values of RS and RD. _____
53. If the transconductance of the JFET used in question 52 is 4000 μmhos, what is the AC voltage gain? _____
54. A certain op-amp circuit uses an input resistance of 8 kV to an inverting input. For the op-amp circuit to have a gain of 85, what should the value of the feedback resistance be? _____
55. If the input to the op-amp circuit of question 54 is 2 mV, what is the output? _____
56. What is an oscillator? _____
57. Why is positive feedback rather than negative feedback necessary in an oscillator? _____
58. What feedback method is used in a Colpitts oscillator? _____
59. What feedback method is used in a Hartley oscillator? _____
60. Draw the circuit of a Colpitts oscillator. _____
61. Draw the circuit of a Hartley oscillator. _____
62. What is the formula used to calculate the output frequency of an oscillator? _____
63. Draw the circuit symbol for a transformer with a center tap. _____
64. Name the two main coils used on a transformer. _____
65. What is the equation that shows the relationship between the input voltage, the output voltage, and the number of turns in each coil of a transformer? _____
66. What is the equation that shows the relationship between the turns ratio and the currents in the primary and secondary coils of the transformer? _____
67. What is the equation that shows the relationship between the impedance of the primary coil, the impedance of the secondary coil, and the number of turns in each coil of a transformer? _____
68. What are the two main uses for transformers? _____
69. Draw a simple half-wave rectifier circuit with a smoothing filter at the output. _____
70. Draw a simple full-wave rectifier circuit using a center tap transformer and a smoothing filter at the output. _____
71. Given a 10 Vrms input to a full-wave rectified power supply, calculate the values of R1, C1 and C2 (see Figure 12.12) that results in a 5-volt DC output across a 50-ohm load. _____
Figure 12.1
Figure 12.2
Figure 12.3
Figure 12.4
Figure 12.5
Figure 12.6
Figure 12.7
Figure 12.8
Figure 12.9
Figure 12.10
Figure 12.11
Figure 12.12
Answers to Final Self-Test
The references in parentheses to the right of the answers give you the chapter and problem number where the material is introduced so that you can easily review any concepts covered in the test.
1. V = 2 volts (Chapter 1, problem 5)
2. I = 0.5 mA (Chapter 1, problem 6)
3. R = 7 ohms (Chapter 1, problem 7)
4. 132 ohms (Chapter 1, problem 10)
5. P = 140 milliwatts or 0.14 watts (Chapter 1, problems 13 and 14)
6. 0.2 watts (Chapter 1, problems 13 and 15)
7. 22.36 mA (Chapter 1, problems 13 and 16)
8. 2.86 volts, 9.14 volts, 12 volts (Chapter 1, problems 23 and 26)
9. 2/3 ampere through the 6-ohm resistor; 1/3 ampere through the 12-ohm resistor (Chapter 1, problem 28 or 29)
10. 91 mA through the 660-ohm resistor; 182 mA through the 330-ohm resistor (Chapter 1, problem 28 or 29)
11. τ = 0.01 seconds (Chapter 1, problem 34)
12. τ = 250 seconds (Chapter 1, problem 34)
13. 6 μF (Chapter 1, problem 40)
14. 52.4 μF (Chapter 1, problem 41)
15. 8.25 μF (Chapter 1, problem 41)
16. Approximately 0.3 volts (Chapter 2, problem 9)
17. Approximately 0.7 volts (Chapter 2, problem 9)
18. ID = 4.3 mA (Chapter 2, problem 12)
19. ID = 120 mA (Chapter 2, problem 12)
20. IZ = 3 mA (Chapter 2, problem 29)
21. IZ = 3.07 mA (Chapter 2, problem 29)
22. VC = 14 volts (Chapter 3, problems 20–23)
23. RB = 1.1 M (Chapter 3, problems 20–23)
24. β = 50 (Chapter 3, problems 20–23)
25. Drain, source, and gate, with the gate acting to control the JFET (Chapter 3, problem 28)
26. RB = 500 k (Chapter 4, problems 8)
27. RB = 470 k (Chapter 4, problems 4–8)
28. R3 = 44 k, R1 = 2.2 k, R2 = 2.2 k (Chapter 4, problems 19–23)
29. R3 = 2.2 k, R1 = 66 k, R2 = 66 k (Chapter 4, problems 19–23)
30. RD = 2 k (Chapter 4, problem 39)
31. See Figure 12.13.
Figure 12.13
(Chapter 5, problem 7)
32. See Figure 12.14.
Figure 12.14
(Chapter 5, problems 3 and 7)
33. 3.535 volts (Chapter 5, problem 4)
34. 340 volts (Chapter 5, problem 5)
35. 69 μsec (Chapter 5, problem 7)
36. 13.3 ohms (Chapter 5, problem 14)
37. 0.32 μF (Chapter 5, problem 14)
38. 27.6 ohms (Chapter 5, problem 17)
39. 16 mH (Chapter 5, problem 17)
40. 8 kHz (Chapter 5, problems 19 and 21)
41. XC = 1.6 k, Z = 2263 ohms, Vout = 7.07 volts, I = 4.4 mA, tan θ = 1, θ = 45 degrees (Chapter 6, problems 10 and 23)
42. XC = 8 k, Z = 10 k, Vout = 72 volts, I = 12 mA, tan θ = 1.33, θ = 53.13 degrees (Chapter 6, problems 10 and 23)
43. XC = 80 ohms, AC Vout = 8 mV, DC Vout = 2.5 volts (Chapter 6, problem 26)
44. XC = 1.33 ohms, AC Vout = 8.3 mV, DC Vout = 2 volts (Chapter 6, problem 26)
45. XL = 62.8 ohms, Z = 89 ohms, AC Vout = 6.07 volts, DC Vout = 4.3 volts, tan θ = 1, θ = 45 degrees (Chapter 6, problems 31 and 35)
46. fr = 16 kHz, XL = 100 ohms, XC = 100 ohms, Z = 10 ohms, Q = 10, BW = 1.6 kHz (Chapter 7, problems 2, 6, and 20)
47. fr = 11,254 Hz, XL = XC = 707 ohms, Z = 71.4 k, Q = 101, BW = 111 Hz (Chapter 7, problems 10, 11, and 20)
48. Vhp = 5.656 volts, f1hp = 11,198 Hz, f2hp = 11,310 Hz (Chapter 7, problem 27)
49. Your values should be close to the following: RE = 100 ohms, VC = 14 volts, VE = 1.4 volts, VB = 2.1 volts, R2 = 1.5 k, R1 = 16.8 k (Chapter 8, problem 17)
50. RE = 110 ohms, VC = 5 volts, VE = 0.25 volts, VB = 0.95 volts, R2 = 2.2 k, R1 = 18.1 k (Chapter 8, problem 17)
51. The gain can be increased by using a capacitor to bypass the emitter resistor RE; CE = 300 μF (approximately). (Chapter 8, problem 20)
52. RS = 1.04 k, RD = 3.41 k (Chapter 8, problem 42)
53. Av = –13.6 (Chapter 8, problem 39)
54. RF = 680 k (Chapter 8, problem 45)
55. Vout = 170 mV and is inverted (Chapter 8, problem 45)