1. Practical Circuits 1 G7 - PRACTICAL CIRCUITS [2 exam question - 2 groups] G7APower supplies; transmitters and receivers; filters; schematic symbols G7BDigital circuits (gates, flip-flops, shift registers); amplifiers and oscillators

2. G7A Power supplies A power-supply bleeder resistor discharges the filter capacitors providing a safety feature A power-supply bleeder resistor discharges the filter capacitors providing a safety feature Capacitors and inductors are used in a power-supply filter network Capacitors and inductors are used in a power-supply filter network The minimum peak-inverse-voltage rating of the rectifier in a full-wave power supply should be double the normal peak output voltage of the power supply The minimum peak-inverse-voltage rating of the rectifier in a full-wave power supply should be double the normal peak output voltage of the power supply The approximate minimum peak-inverse-voltage rating of the rectifier in a half-wave power supply should be two times the normal peak output voltage of the power supply The approximate minimum peak-inverse-voltage rating of the rectifier in a half-wave power supply should be two times the normal peak output voltage of the power supply Practical Circuits 2

3. G7A Power supplies cont’d A desirable characteristic for capacitors used to filter the DC output of a switching power supply is low equivalent series resistance A desirable characteristic for capacitors used to filter the DC output of a switching power supply is low equivalent series resistance An advantage of a switched-mode power supply as compared to a linear power supply is high frequency operation allows the use of smaller components An advantage of a switched-mode power supply as compared to a linear power supply is high frequency operation allows the use of smaller components A 180 degree portion of the AC cycle is converted to DC by a half-wave rectifier A 180 degree portion of the AC cycle is converted to DC by a half-wave rectifier A 360 degree portion of the AC cycle is converted to DC by a full-wave rectifier A 360 degree portion of the AC cycle is converted to DC by a full-wave rectifier The output waveform of an unfiltered full-wave rectifier connected to a resistive load is a series of DC pulses at twice the frequency of the AC input The output waveform of an unfiltered full-wave rectifier connected to a resistive load is a series of DC pulses at twice the frequency of the AC input Practical Circuits 3

4. 7A Transmitters A Balanced modulator circuit is used to combine signals from the carrier oscillator and speech amplifier and send the result to the filter in a typical single-sideband phone transmitter A Balanced modulator circuit is used to combine signals from the carrier oscillator and speech amplifier and send the result to the filter in a typical single-sideband phone transmitter An advantage of a crystal controlled transmitter is stable output frequency An advantage of a crystal controlled transmitter is stable output frequency Practical Circuits 4

5. G7A Receivers A Mixer circuit is used to process signals from the RF amplifier and local oscillator and send the results to the IF filter in a super heterodyne receiver A Mixer circuit is used to process signals from the RF amplifier and local oscillator and send the results to the IF filter in a super heterodyne receiver A Product detector circuit is used to process signals from the IF amplifier and BFO and send the result to the AF amplifier in a single-sideband phone superheterodyne receiver A Product detector circuit is used to process signals from the IF amplifier and BFO and send the result to the AF amplifier in a single-sideband phone superheterodyne receiver The simplest combination of stages that can be combined to implement a superhedterodyne receiver is an HF oscillator, mixer, and detector The simplest combination of stages that can be combined to implement a superhedterodyne receiver is an HF oscillator, mixer, and detector Practical Circuits 5

6. G7A Receivers cont’d A direct conversion receiver is suitable for CW and SSB reception but does not require a mixer stage or an IF amplifier A direct conversion receiver is suitable for CW and SSB reception but does not require a mixer stage or an IF amplifier A Discriminator circuit is used in many FM receivers to convert signals coming from the IF amplifier to audio A Discriminator circuit is used in many FM receivers to convert signals coming from the IF amplifier to audio Practical Circuits 6

7. G7A Filters The impedance of a low-pass filter as compared to the impedance of the transmission line into which it is to be inserted should be about the same The impedance of a low-pass filter as compared to the impedance of the transmission line into which it is to be inserted should be about the same A Filter might be used to process signals from the balanced modulator and send them to the mixer in a single-sideband phone transmitter A Filter might be used to process signals from the balanced modulator and send them to the mixer in a single-sideband phone transmitter Practical Circuits 7

8. G7A Schematic drawing symbols 3. Fixed resistor 3. Fixed resistor 4. NPN Transistor 4. NPN Transistor 5. Variable capacitor 5. Variable capacitor 6. Transformer 6. Transformer 11. Single pole switch 11. Single pole switch 13. Single cell battery 13. Single cell battery Practical Circuits 8

9. 9 G7A01 What safety feature does a power- supply bleeder resistor provide? A.It acts as a fuse for excess voltage B.It discharges the filter capacitors C.It removes shock hazards from the induction coils D.It eliminates ground-loop current

10. Practical Circuits 10 G7A01 What safety feature does a power- supply bleeder resistor provide? A.It acts as a fuse for excess voltage B.It discharges the filter capacitors C.It removes shock hazards from the induction coils D.It eliminates ground-loop current

11. Practical Circuits 11 G7A02 What components are used in a power-supply filter network? A.Diodes B.Transformers and transistors C.Quartz crystals D.Capacitors and inductors

12. Practical Circuits 12 G7A02 What components are used in a power-supply filter network? A.Diodes B.Transformers and transistors C.Quartz crystals D.Capacitors and inductors

13. Practical Circuits 13 G7A03 What should be the minimum peak- inverse-voltage rating of the rectifier in a full-wave power supply? A.One-quarter the normal output voltage of the power supply B.Half the normal output voltage of the power supply C.Double the normal peak output voltage of the power supply D.Equal to the normal output voltage of the power supply

14. Practical Circuits 14 G7A03 What should be the minimum peak- inverse-voltage rating of the rectifier in a full-wave power supply? A.One-quarter the normal output voltage of the power supply B.Half the normal output voltage of the power supply C.Double the normal peak output voltage of the power supply D.Equal to the normal output voltage of the power supply

15. Practical Circuits 15 G7A04 What should be the approximate minimum peak-inverse-voltage rating of the rectifier in a half-wave power supply? A.One-half the normal peak output voltage of the power supply B.Half the normal output voltage of the power supply C.Equal to the normal output voltage of the power supply D.Two times the normal peak output voltage of the power supply

16. Practical Circuits 16 G7A04 What should be the approximate minimum peak-inverse-voltage rating of the rectifier in a half-wave power supply? A.One-half the normal peak output voltage of the power supply B.Half the normal output voltage of the power supply C.Equal to the normal output voltage of the power supply D.Two times the normal peak output voltage of the power supply

17. Practical Circuits 17 G7A05 What should be the impedance of a low-pass filter as compared to the impedance of the transmission line into which it is inserted? A.Substantially higher B.About the same C.Substantially lower D.Twice the transmission line impedance

18. Practical Circuits 18 G7A05 What should be the impedance of a low-pass filter as compared to the impedance of the transmission line into which it is inserted? A.Substantially higher B.About the same C.Substantially lower D.Twice the transmission line impedance

19. Practical Circuits 19 G7A06 Which of the following might be used to process signals from the balanced modulator and send them to the mixer in a single-sideband phone transmitter? A.Carrier oscillator B.Filter C.IF amplifier D.RF amplifier

20. Practical Circuits 20 G7A06 Which of the following might be used to process signals from the balanced modulator and send them to the mixer in a single-sideband phone transmitter? Mic Speech Amp Balanced Modulator Carrier Oscillator LSBUSB IF Filter IF AmpIF Mixer VFO Mixer IF AmpPower Amp Second Oscillator VFO Antenna

21. Practical Circuits 21 G7A06 Which of the following might be used to process signals from the balanced modulator and send them to the mixer in a single-sideband phone transmitter? A.Carrier oscillator B.Filter C.IF amplifier D.RF amplifier Mic Speech Amp Balanced Modulator Carrier Oscillator LSBUSB IF Filter IF Amp IF Mixer VFO Mixer IF Amp Power Amp Second Oscillator VFO Antenna

22. Practical Circuits 22 G7A07 Which circuit is used to combine signals from the carrier oscillator and speech amplifier and send the result to the filter in a typical single-sideband phone transmitter? A.Mixer B.Detector C.IF amplifier D.Balanced modulator

23. Practical Circuits 23 G7A07 Which circuit is used to combine signals from the carrier oscillator and speech amplifier and send the result to the filter in a typical single-sideband phone transmitter? A.Mixer B.Detector C.IF amplifier D.Balanced modulator Mic Speech Amp Balanced Modulator Carrier Oscillator LSBUSB IF Filter IF Amp IF Mixer VFO Mixer IF Amp Power Amp Second Oscillator VFO Antenna

24. Practical Circuits 24 G7A08 What circuit is used to process signals from the RF amplifier and local oscillator and send the result to the IF filter in a superheterodyne receiver? A.Balanced modulator B.IF amplifier C.Mixer D.Detector

25. Practical Circuits 25 G7A08 What circuit is used to process signals from the RF amplifier and local oscillator and send the result to the IF filter in a superheterodyne receiver? A.Balanced modulator B.IF amplifier C.Mixer D.Detector

26. Practical Circuits 26 G7A09 What circuit is used to process signals from the IF amplifier and BFO and send the result to the AF amplifier in a single-sideband phone superheterodyne receiver? A.RF oscillator B.IF filter C.Balanced modulator D.Product detector

27. Practical Circuits 27 G7A09 What circuit is used to process signals from the IF amplifier and BFO and send the result to the AF amplifier in a single-sideband phone superheterodyne receiver? A.RF oscillator B.IF filter C.Balanced modulator D.Product detector

28. Practical Circuits 28 G7A10 What is an advantage of a crystal controlled transmitter? A.Stable output frequency B.Excellent modulation clarity C.Ease of switching between bands D.Ease of changing frequency

29. Practical Circuits 29 G7A10 What is an advantage of a crystal controlled transmitter? A.Stable output frequency B.Excellent modulation clarity C.Ease of switching between bands D.Ease of changing frequency

30. Practical Circuits 30 G7A11 What is the simplest combination of stages that can be combined to implement a superheterodyne receiver? A.RF amplifier, detector, audio amplifier B.RF amplifier, mixer, if amplifier C.HF oscillator, mixer, detector D.HF oscillator, product detector, audio amplifier

31. Practical Circuits 31 G7A11 What is the simplest combination of stages that can be combined to implement a superheterodyne receiver? A.RF amplifier, detector, audio amplifier B.RF amplifier, mixer, if amplifier C.HF oscillator, mixer, detector D.HF oscillator, product detector, audio amplifier

32. Practical Circuits 32 G7A12 What type of receiver is suitable for CW and SSB reception but does not require a mixer stage or an IF amplifier? A.A super-regenerative receiver B.A TRF receiver C.A super-heterodyne receiver D.A direct conversion receiver

33. Practical Circuits 33 G7A12 What type of receiver is suitable for CW and SSB reception but does not require a mixer stage or an IF amplifier? A.A super-regenerative receiver B.A TRF receiver C.A super-heterodyne receiver D.A direct conversion receiver

34. Practical Circuits 34 G7A13 What type of circuit is used in many FM receivers to convert signals coming from the IF amplifier to audio? A.Product detector B.Phase inverter C.Mixer D.Discriminator

35. Practical Circuits 35 G7A13 What type of circuit is used in many FM receivers to convert signals coming from the IF amplifier to audio? A.Product detector B.Phase inverter C.Mixer D.Discriminator

36. Practical Circuits 36 G7A14 Which of the following is a desirable characteristic for capacitors used to filter the DC output of a switching power supply? A.Low equivalent series resistance B.High equivalent series resistance C.Low Temperature coefficient D.High Temperature coefficient

37. Practical Circuits 37 G7A14 Which of the following is a desirable characteristic for capacitors used to filter the DC output of a switching power supply? A.Low equivalent series resistance B.High equivalent series resistance C.Low Temperature coefficient D.High Temperature coefficient

38. Practical Circuits 38 G7A15 Which of the following is an advantage of a switched-mode power supply as compared to a linear power supply? A.Faster switching time makes higher output voltage possible B.Fewer circuit components are required C.High frequency operation allows the use of smaller components D.All of these choices are correct

39. Practical Circuits 39 G7A15 Which of the following is an advantage of a switched-mode power supply as compared to a linear power supply? A.Faster switching time makes higher output voltage possible B.Fewer circuit components are required C.High frequency operation allows the use of smaller components D.All of these choices are correct

40. Practical Circuits 40 Half Wave Rectifier

41. Practical Circuits 41 G7A16 What portion of the AC cycle is converted to DC by a half-wave rectifier? A.90 degrees B.180 degrees C.270 degrees D.360 degrees

42. Practical Circuits 42 G7A16 What portion of the AC cycle is converted to DC by a half-wave rectifier? A.90 degrees B.180 degrees C.270 degrees D.360 degrees

43. Practical Circuits 43 G7A17 What portion of the AC cycle is converted to DC by a full-wave rectifier? A.90 degrees B.180 degrees C.270 degrees D.360 degrees

44. Practical Circuits 44 G7A17 What portion of the AC cycle is converted to DC by a full-wave rectifier? A.90 degrees B.180 degrees C.270 degrees D.360 degrees

45. Practical Circuits 45 G7A18 What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load? A.A series of DC pulses at twice the frequency of the AC input B.A series of DC pulses at the same frequency as the AC input C.A sine wave at half the frequency of the AC input D.A steady DC voltage

46. Practical Circuits 46 G7A18 What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load? A.A series of DC pulses at twice the frequency of the AC input B.A series of DC pulses at the same frequency as the AC input C.A sine wave at half the frequency of the AC input D.A steady DC voltage

47. Practical Circuits 47 G7A19 Which symbol in figure G7-1 represents a fixed resistor? A.Symbol 2 B.Symbol 6 C.Symbol 3 D.Symbol 12

48. Practical Circuits 48 G7A19 Which symbol in figure G7-1 represents a fixed resistor? A.Symbol 2 B.Symbol 6 C.Symbol 3 D.Symbol 12

49. Practical Circuits 49 G7A20 Which symbol in figure G7-1 represents a single cell battery? A.Symbol 5 B.Symbol 12 C.Symbol 8 D.Symbol 13

50. Practical Circuits 50 G7A20 Which symbol in figure G7-1 represents a single cell battery? A.Symbol 5 B.Symbol 12 C.Symbol 8 D.Symbol 13

51. Practical Circuits 51 G7A21 Which symbol in figure G7-1 represents a NPN transistor? A.Symbol 2 B.Symbol 4 C.Symbol 10 D.Symbol 12

52. Practical Circuits 52 G7A21 Which symbol in figure G7-1 represents a NPN transistor? A.Symbol 2 B.Symbol 4 C.Symbol 10 D.Symbol 12

53. Practical Circuits 53 G7A22 Which symbol in figure G7-1 represents a variable capacitor? A.Symbol 2 B.Symbol 11 C.Symbol 5 D.Symbol 12

54. Practical Circuits 54 G7A22 Which symbol in figure G7-1 represents a variable capacitor? A.Symbol 2 B.Symbol 11 C.Symbol 5 D.Symbol 12

55. Practical Circuits 55 G7A23 Which symbol in figure G7-1 represents a transformer? A.Symbol 6 B.Symbol 4 C.Symbol 10 D.symbol 2

56. Practical Circuits 56 G7A23 Which symbol in figure G7-1 represents a transformer? A.Symbol 6 B.Symbol 4 C.Symbol 10 D.symbol 2

57. Practical Circuits 57 G7A24 Which symbol in figure G7-1 represents a single pole switch? A.Symbol 2 B.Symbol 3 C.Symbol 11 D.Symbol 12

58. Practical Circuits 58 G7A24 Which symbol in figure G7-1 represents a single pole switch? A.Symbol 2 B.Symbol 3 C.Symbol 11 D.Symbol 12

59. G7B Digital circuits (gates, flip-flops, shift registers A “flip-flop” circuit is a digital circuit with two stable states A “flip-flop” circuit is a digital circuit with two stable states Digital circuits use the binary number system because binary “ones” and “zeros” are easy to represent with an “on” and “off” state Digital circuits use the binary number system because binary “ones” and “zeros” are easy to represent with an “on” and “off” state The output of a two-input NAND gate, given both inputs are “one” is Zero The output of a two-input NAND gate, given both inputs are “one” is Zero Practical Circuits 59

60. G7B Digital circuits cont’d The output of a NOR gate given that both inputs are “zero” is one The output of a NOR gate given that both inputs are “zero” is one There are 8 states in a 3-bit binary counter There are 8 states in a 3-bit binary counter A shift register is a clocked array of circuits that passes data in steps along the array A shift register is a clocked array of circuits that passes data in steps along the array Practical Circuits 60

61. G7B Amplifiers Low distortion is a characteristic of a Class A amplifier Low distortion is a characteristic of a Class A amplifier A Class “C” power stage is appropriate for amplifying a modulated signal for the CW mode A Class “C” power stage is appropriate for amplifying a modulated signal for the CW mode High efficiency is an advantage of a Class C amplifier High efficiency is an advantage of a Class C amplifier The efficiency of an RF power amplifier is determined by dividing the RF output power by the DC input power The efficiency of an RF power amplifier is determined by dividing the RF output power by the DC input power A linear amplifier is an amplifier whose output preserves the input waveform A linear amplifier is an amplifier whose output preserves the input waveform Practical Circuits 61

62. G7B Oscillators The basic components of virtually all oscillators are a filter and and amplifier operating in a feedback loop The basic components of virtually all oscillators are a filter and and amplifier operating in a feedback loop The phase shift of the RC feedback circuit determines the frequency of an RC oscillator The phase shift of the RC feedback circuit determines the frequency of an RC oscillator * The inductance and capacitance in the tank circuit determines the frequency of an LC oscillator Practical Circuits 62

63. Practical Circuits 63 G7B01 Which of the following describes a "flip-flop" circuit? A.A transmit-receive circuit B.A digital circuit with two stable states C.An RF limiter D.A voice-operated switch

64. Practical Circuits 64 G7B01 Which of the following describes a "flip-flop" circuit? A.A transmit-receive circuit B.A digital circuit with two stable states C.An RF limiter D.A voice-operated switch

65. Practical Circuits 65 G7B02 Why do digital circuits use the binary number system? A.Binary "ones" and "zeros" are easy to represent with an "on" or "off" state B.The binary number system is most accurate C.Binary numbers are more compatible with analog circuitry D.All of these answers are correct

66. Practical Circuits 66 G7B02 Why do digital circuits use the binary number system? A.Binary "ones" and "zeros" are easy to represent with an "on" or "off" state B.The binary number system is most accurate C.Binary numbers are more compatible with analog circuitry D.All of these answers are correct

67. Practical Circuits 67 G7B03 What is the output of a two-input NAND gate, given both inputs are "one"? A.Two B.One C.Zero D.Minus One

68. Practical Circuits 68 G7B03 What is the output of a two-input NAND gate, given both inputs are "one"? A.Two B.One C.Zero D.Minus One

69. Practical Circuits 69 G7B04 What is the output of a NOR gate given that both inputs are "zero"? A.Zero B.One C.Minus one D.The opposite from the previous state

70. Practical Circuits 70 G7B04 What is the output of a NOR gate given that both inputs are "zero"? A.Zero B.One C.Minus one D.The opposite from the previous state

71. Practical Circuits 71 G7B05 How many states are there in a 3-bit binary counter? A.3 B.6 C.8 D.16

72. Practical Circuits 72 G7B05 How many states are there in a 3-bit binary counter? A.3 B.6 C.8 D.16

73. Practical Circuits 73 G7B06 What is a shift register? A.A clocked array of circuits that passes data in steps along the array B.An array of operational amplifiers used for tri-state arithmetic operations C.A digital mixer D.An analog mixer

74. Practical Circuits 74 G7B06 What is a shift register? A.A clocked array of circuits that passes data in steps along the array B.An array of operational amplifiers used for tri-state arithmetic operations C.A digital mixer D.An analog mixer

75. Practical Circuits 75 G7B07 What are the basic components of virtually all oscillators? A.An amplifier and a divider B.A frequency multiplier and a mixer C.A circulator and a filter operating in a feed-forward loop D.A filter and an amplifier operating in a feedback loop

76. Practical Circuits 76 G7B07 What are the basic components of virtually all oscillators? A.An amplifier and a divider B.A frequency multiplier and a mixer C.A circulator and a filter operating in a feed-forward loop D.A filter and an amplifier operating in a feedback loop

77. Practical Circuits 77 G7B08 What determines the frequency of an RC oscillator? A.The ratio of the capacitors in the feedback loop B.The value of the inductor in the tank circuit C.The phase shift of the RC feedback circuit D.The gain of the amplifier

78. Practical Circuits 78 G7B08 What determines the frequency of an RC oscillator? A.The ratio of the capacitors in the feedback loop B.The value of the inductor in the tank circuit C.The phase shift of the RC feedback circuit D.The gain of the amplifier

79. Practical Circuits 79 G7B09 What determines the frequency of an LC oscillator? A.The number of stages in the counter B.The number of stages in the divider C.The inductance and capacitance in the tank circuit D.The time delay of the lag circuit

80. Practical Circuits 80 G7B09 What determines the frequency of an LC oscillator? A.The number of stages in the counter B.The number of stages in the divider C.The inductance and capacitance in the tank circuit D.The time delay of the lag circuit

81. Practical Circuits 81 G7B10 Which of the following is a characteristic of a Class A amplifier? A.Low standby power B.High Efficiency C.No need for bias D.Low distortion

82. Practical Circuits 82 G7B10 Which of the following is a characteristic of a Class A amplifier? A.Low standby power B.High Efficiency C.No need for bias D.Low distortion

83. Practical Circuits 83 G7B11 For which of the following modes is a Class C power stage appropriate for amplifying a modulated signal? A.SSB B.CW C.AM D.All of these answers are correct

84. Practical Circuits 84 G7B11 For which of the following modes is a Class C power stage appropriate for amplifying a modulated signal? A.SSB B.CW C.AM D.All of these answers are correct

85. Practical Circuits 85 G7B12 Which of the following is an advantage of a Class C amplifier? A.High efficiency B.Linear operation C.No need for tuned circuits D.All of these answers are correct

86. Practical Circuits 86 G7B12 Which of the following is an advantage of a Class C amplifier? A.High efficiency B.Linear operation C.No need for tuned circuits D.All of these answers are correct

87. Practical Circuits 87 G7B13 How is the efficiency of an RF power amplifier determined? A.Divide the DC input power by the DC output power B.Divide the RF output power by the DC input power C.Multiply the RF input power by the reciprocal of the RF output power D.Add the RF input power to the DC output power

88. Practical Circuits 88 G7B13 How is the efficiency of an RF power amplifier determined? A.Divide the DC input power by the DC output power B.Divide the RF output power by the DC input power C.Multiply the RF input power by the reciprocal of the RF output power D.Add the RF input power to the DC output power

89. Practical Circuits 89 G7B14 Which of the following describes a linear amplifier? G7B14 Which of the following describes a linear amplifier? A.Any RF power amplifier used in conjunction with an amateur transceiver B.An amplifier whose output preserves the input waveform C.A Class C high efficiency amplifier D.An amplifier used as a frequency multiplier

90. Practical Circuits 90 G7B14 Which of the following describes a linear amplifier? A.Any RF power amplifier used in conjunction with an amateur transceiver B.An amplifier whose output preserves the input waveform C.A Class C high efficiency amplifier D.An amplifier used as a frequency multiplier

91. Practical Circuits 91 G7 - PRACTICAL CIRCUITS [2 exam question - 2 groups]