Module 8 Index

INDEX-1

Module 8 Index

A Amplifier frequency response, 2-2 to 2-11 bandwidth of an amplifier, 2-3 to 2-5 factors affecting frequency response of an amplifier, 2-9 to 2-11 reading amplifier frequency-response curve, 2-5 to 2-7 Amplifier input/output impedance and gain, 2-18, 2-19 Amplifiers, 1-1 to 1-29 audio, 1-24 to 1-29 phase splitters, 1-24 to 1-26 push-pull amplifiers, 1-27 to 1-28 single-stage, 1-28, 1-29 classification of, 1-25 to 1-26 frequency response of amplifiers, 1-5 voltage amplifiers and power amplifiers, 1-3, 1-4 introduction, 1-1, 1-2 summary, 1-29 to 1-38 transistor, 1-5 to 1-24 classes of operation, 1-6 to 1-9 coupling, 1-9 to 1-13 feedback, 1-17 to 1-24 impedance considerations for, 1-14 to 1-17 Amplifiers, special, 3-1 to 3-57 differential amplifiers, 3-2 to 3-14 basic differential amplifier circuit, 3-2 differential-input, differential-output, differential amplifier, 3-13 single-input, differential-output, differential amplifier, 3-12 single-input, single-output, differential amplifier, 3-11 two-input, single-output, difference amplifier, 3-3 to 3-10 typical differential amplifier circuit, 3-10 introduction, 3-1 magnetic amplifiers, 3-42 to 3-57 basic operation, 3-42 to 3-44 Amplifiers, special—Continued methods of changing inductance, 3-44 to 3-46 saturable-core reactor, 3-46 to 3-52 simplified magnetic amplifier circuitry, 3-52 to 3-57 operational amplifiers, 3-15 to 3-41 applications, 3-29 to 3-40 bandwidth limitations, 3-25 to 3-28 block diagram, 3-16 to 3-18 characteristics, 3-15 closed-loop operation, 3-18 to 3-23 summary, 3-57 to 3-69 Amplifiers, video, 2-12 to 2-16 high-frequency compensation, 2-12 low-frequency compensation, 2-15, 2-16 typical video-amplifier circuit, 2-16 Applications of operational amplifiers, 3-29 to 3-40 Audio amplifiers, 1-24 to 1-26 phase splitters, 1-27, 1-28 push-pull amplifiers, 1-28, 1-29 single-stage, 1-25, 1-26 B Bandwidth limitations, operational amplifiers, 3-25 to 3-28 Bandwidth of an amplifier, 2-3 to 2-5 Block diagram, operational amplifiers, 3-16 to 3-18 C Changing inductance, methods of, magnetic amplifiers, 3-44 to 3-46 Classes of operation, amplifier, 1-6 to 1-9 class A, 1-6, 1-7 class AB, 1-7 class B, 1-7, 1-8 class C, 1-8, 1-9 Classification of amplifiers, 1-3, 1-4 frequency response, 1-5 voltage amplifiers and power amplifiers, 1-3, 1-4 INDEX-2 Closed-loop operation, operational amplifiers, 3-18 to 3-23 Combination peaking, 2-14, 2-15 Compensation of rf amplifiers, 2-23 to 2-25 neutralization, 2-24, 2-25 transformers, 2-23 Coupling, amplifiers, 1-9 to 1-13 direct, 1-10, 1-11 impedance, 1-12, 1-13

Rc, 1-11, 1-12

transformer, 1-13 Coupling, rf amplifier, 2-21 to 2-23 D Differential amplifiers, 3-2 to 3-14 basic differential amplifier circuit, 3-2 differential-input, differential-output, differential amplifier, 3-13 single-input, differential-output, differential amplifier, 3-12 single-input, single-output, differential amplifier, 3-11 two-input, single-output, difference amplifier, 3-3 to 3-10 typical differential amplifier circuit, 3-10 Direct coupling, 1-10, 1-11 F Factors affecting frequency response of an amplifier, 2-9 to 2-11 Feedback, amplifier, 1-17 to 1-24 negative, 1-23, 1-24 positive, 1-20 to 1-23 Frequency-determining network, rf amplifier, 2-19 Frequency-response curve, reading amplifier, 2-5 to 2-7 Frequency response of amplifiers, 1-5 G Glossary, AI-l to AI-3 H High-frequency compensation for video, 2-12 to 2-16 amplifiers, 2-12 to 2-15 combination peaking, 2-14, 2-15 series peaking, 2-12, 2-13 shunt peaking, 2-13, 2-14 I Impedance considerations for amplifiers, 1-14 to 1-17 Impedance coupling, 1-12, 1-13 L Learning objectives, video and rf amplifiers, 2-1 Low-frequency compensation for video amplifiers, 2-15, 2-16 M Magnetic amplifiers, 3-42 to 3-57 basic operation, 3-42 to 3-44 methods of changing inductance, 3-44 to 3-46 saturable-core reactor, 3-46 to 3-52 simplified magnetic amplifier circuitry, 3-52 to 3-57 O Operational amplifiers, 3-15 to 3-41 applications, 3-29 to 3-40 difference amplifier (subtractor), 3-36 to 3-40 summing amplifier (adder), 3-29 to 3-35 bandwidth limitations, 3-25 to 3-28 block diagram, 3-16, 3-17 characteristics, 3-15 closed-loop operation, 3-18 to 3-28 inverting configuration, 3-18 to 3-23 noninverting configuration, 3-23 to 3-28 INDEX-3 P Peaking, high-frequency compensation for video amplifiers, 2-12 to 2-15 combination, 2-14 series, 2-13 shunt, 2-12 Phase splitters, 1-27, 1-28 Power amplifiers and voltage amplifiers, 1-3, 1-4 Push-pull amplifiers, 1-28, 1-29 R Radio-frequency amplifiers, 2-17 to 2-27 amplifier input/output impedance and gain, 2-18, 2-19 compensation, 2-23 to 2-25 frequency-determining network, 2-19 rf amplifier coupling, 2-21 to 2-23 typical circuits, 2-25 to 2-27 RC coupling, 1-11, 1-12 Reading amplifier frequency-response curve, 2-9 S Saturable-core reactor, magnetic amplifiers, 3-46 to 3-52 Series peaking, 2-12, 2-13 Shunt peaking, 2-13, 2-14 Single-stage audio amplifiers, 1-25, 1-26 T Transformer coupling, 1-13 Transistor amplifiers, 1-5 to 1-24 classes of operation, 1-6 to 1-9 coupling, 1-9 to 1-13 feedback, 1-17 to 1-24 Transistor amplifiers—Continued impedance considerations for amplifiers, 1-14 to 1-17 V Video and rf amplifiers, 2-1 to 2-27 amplifier frequency response, 2-5 to 2-7 bandwidth of an amplifier, 2-3 to 2-5 factors affecting frequency response of an amplifier, 2-9 to 2-11 reading amplifier frequency-response curve, 2-5 to 2-7 introduction, 2-1 learning objectives, 2-1 radio-frequency amplifiers, 2-17 to 2-27 amplifier input/output impedance and gain, 2-18, 2-19 compensation, 2-23 to 2-25 frequency-determining network, 2-19 rf amplifier coupling, 2-21 to 2-23 typical circuits, 2-25 to 2-27 summary, 2-28 to 2-33 video amplifiers, 2-12 to 2-15 high-frequency compensation, 2-12, 2-13 low-frequency, 2-15 to 2-16 typical video-amplifier circuit, 2-16 Voltage amplifiers and power amplifiers, 1-3, 1-4 Assignment Questions Information: The text pages that you are to study are provided at the beginning of the assignment questions.

1

Assignment 1

Textbook assignment: Chapter 1, “Amplifiers,” pages 1-1 through 1-40. Chapter 2, “Video and RF Amplifiers,” pages 2-1 through 2-34. _________________________________________________________________________________ 1-1. The control of an output signal by an input signal resulting in the output signal having some (or all) of the characteristics of the input signal is known by which of the following terms? 1. Multiplication 2. Magnification 3. Amplification 4. Addition 1-2. Which of the following statements describes the relationship of input and output signals in a amplifier?

1. The input signal is actually changed into the output signal 2. Both the input and output signal are unchanged; neither is affected by the other 3. The input signal is controlled by the output signal and the output signal remains unchanged 4. The input signal remains unchanged and the output signal is controlled by the input signal 1-3. Why are amplifiers used in electronic devices? 1. To provide signals of usable amplitude 2. To "pick up" broadcast signals 3. To select the proper broadcast signal 4. To change the broadcast signal to an audio signal 1-4. Most amplifiers can be classified in which of the following ways?

1. Function and size 2. Power requirements and size 3. Function and frequency response 4. Frequency response and power requirements 1-5. The speaker system of a record player should be driven by which of the following types of amplifier? 1. An audio power amplifier 2. A video voltage amplifier 3. A direct-current voltage amplifier 4. An alternating-current rf amplifier 1-6. The signal from a radio antenna should be amplified by which of the following types of amplifier? 1. An rf voltage amplifier 2. A video power amplifier 3. A direct-current audio amplifier 4. An alternating-current power amplifier 1-7. The class of operation of an amplifier is determined by which of the following factors?

1. The gain of the stage 2. The efficiency of the amplifier 3. The amount of time (in relation to the input signal) that current flows in the output circuit 4. The amount of current (in relation to the input-signal current) that flows in the output circuit 2 1-8. Which of the following is NOT a class of operation for an amplifier? 1. A 2. C 3. AB 4. AC 1-9. If the output of a circuit should be a representation of less than one-half of the input signal, what class of operation should be used? 1. A 2. C 3. AB 4. AC 1-10. What class of operation is the most efficient?

1. A 2. C 3. AB 4. AC 1-11. What class of operation has the highest fidelity? 1. A 2. C 3. AB 4. AC 1-12. What is the purpose of an amplifier- coupling network? 1. To "block" d.c. 2. To provide gain between stages 3. To separate one stage from another 4. To transfer energy from one stage to another 1-13. Which of the following is NOT a method of coupling amplifier stages? 1. RC 2. Resistor 3. Impedance 4. Transformer 1-14. What is the most common form of coupling? 1. RC 2. Resistor 3. Impedance 4. Transformer 1-15. Which of the following types of coupling is usually used to couple the output from a power amplifier?

1. RC 2. Resistor 3. Impedance 4. Transformer 1-16. Which of the following types of amplifiers have both high and low frequency response limitations? 1. RC 2. Resistor 3. Impedance 4. Transformer 1-17. Which of the following types of coupling is most effective at high frequencies? 1. RC 2. Resistor 3. Impedance 4. Direct

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3 1-18. For maximum power transfer between circuits, what impedance relationship should there be between the two circuits? 1. The output impedance of circuit number one should be higher 2. The input impedance of circuit number one should be higher than the output impedance of circuit .number two 3. The output impedance of circuit number one should be lower than the input impedance of circuit number two 4. The output impedance of circuit number one should be equal to the input impedance of circuit number two 1-19. For maximum current at the input to a circuit, what should the relationship of the input impedance be to the output impedance of the previous stage?

1. Higher than 2. Lower than 3. Equal to 4. The impedance relationship is immaterial 1-20. What is the (a) input impedance and (b) output impedance of a common-base transistor configuration? 1. (a) Low (b) low 2. (a) Low (b) high 3. (a) High (b) low 4. (a) High (b) high 1-21. What transistor configuration should be used to match a high output impedance to a low input impedance? 1. Common collector 2. Common emitter 3. Common gate 4. Common base 1-22. What type of coupling is most useful for impedance matching? 1. RC 2. Resistor 3. Impedance 4. Transformer 1-23. What is feedback?

1. The control of a circuit output signal by the input signal 2. The control of a circuit input signal by the output signal 3. The coupling of a portion of the output signal to the input of the circuit 4. The coupling of a portion of the input signal to the output of the circuit 1-24. Which of the following terms describe the two types of feedback? 1. Positive and negative 2. Degenerative and regenerative 3. Both 1 and 2 above 4. Bypassed and unbypassed 1-25. What type of feedback provide an increased amplitude output signal?

1. Positive 2. Negative 3. Bypassed 4. Unbypassed 1-26. Distortion caused by amplifier saturation can be reduced by using which of the following types of feedback? 1. Positive 2. Negative 3. Regenerative 4. Unbypassed 4 1-27. What type feedback is provided if the feedback signal is out of phase with the input signal? 1. Unbypassed 2. Bypassed 3. Negative 4. Positive 1-28. What type of feedback is provided by a capacitor connected across the emitter- resistor in a common-emitter transistor amplifier? 1. Bypassed 2. Positive 3. Negative 4. Unbypassed 1-29. What are the (a) inputs and (b) outputs of a phase splitter?

1. (a) Two signals in phase (b) One signal 2. (a) Two signals out of phase (b) One signal 3. (a) One signal (b) Two signals in phase 4. (a) One signal (b) Two signals out of phase 1-30. A single-stage, two transistor amplifier that uses a phase splitter input is classified as what type of amplifier? 1. Inverse 2. Push-pull 3. Phase splitter 4. Regenerative 1-31. Which of the following is a common use for a push-pull amplifier? 1. The first stage of a video amplifier 2. The amplifier stage connected directly to an antenna 3. The second stage in a four stage rf amplifier 4. The final stage in an audio amplifier 1-32. What is the advantage of a push-pull amplifier as compared to a single transistor amplifier?

1. Lower cost 2. Fewer parts 3. Higher gain 4. Less power usage 1-33. To provide good fidelity output signals, which of the following classes of operation CANNOT be used by a push- pull amplifier? 1. A 2. B 3. C 4. AB 1-34. What is the bandwidth of an amplifier? 1. The actual frequencies the amplifier is effective in amplifying 2. The difference between the high and low frequencies seen at the input of the amplifier 3. The width, in inches, between the half-power points on a frequency- response curve 4. The difference between the lowest and highest frequency shown on a frequency-response curve

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5 Figure 1A.—Frequency-response curve.

In Answering Questions 1-35 And

1-36 REFER TO FIGURE 1A. 1-35. What are the (a) upper and (b) lower frequency limits shown? 1. (a) 8 kHz (b) 0 Hz 2. (a) 7.5 kHz (b) 0 Hz 3. (a) 6.0 kHz (b) 2 kHz 4. (a) 5.5 kHz (b) 2.5 kHz 1-36. What is the bandwidth shown? 1. 1 inch 2. 8 kHz 3. 3 kHz 4. 2 kHz to 8 kHz 1-37. Which of the following limit(s) the frequency response of a transistor amplifier? 1. The inductance 2. The transistor 3. The capacitance 4. All of the above 1-38. What type of feedback is caused by interelectrode capacitance? 1. Bypassed 2. Negative 3. Positive 4. Regenerative 1-39. What happens to capacitive reactance as frequency decreases?

1. It increases 2. It decreases 3. It remains the same 4. It cannot be determined 1-40. What happens to inductive reactance as frequency increases? 1. It increases 2. It decreases 3. It remains the same 4. It cannot be determined 1-41. What is the major factor that limits the high frequency response of an amplifier? 1. Inductance 2. Resistance 3. Capacitance 4. Transformer reactance 1-42. What components can be used to increase the high-frequency response of an amplifier? 1. Diodes 2. Inductors 3. Resistors 4. Capacitors 1-43. What determines whether a peaking component is considered "series" or "shunt"?

1. The relationship of the component to the power supply 2. The relationship of the component to the input signal path 3. The relationship of the component to the amplifying device 4. The relationship of the component to the output signal path 6 1-44. What is the arrangement of both "series" and "shunt" peaking components called? 1. Coordinated 2. Combination 3. Combined 4. Complex 1-45. Which of the following components in a transistor amplifier circuit tends to limit the low-frequency response of the amplifier? 1. The transistor 2. The load resistor 3. The coupling capacitor 4. The input-signal-developing resistor Figure 1B.—Video Amplifier.

In Answering Questions 1-46

Through 1-52, Refer To Figure 1B.

1-46. What is the purpose of L1 in relation to Q1? 1. Decoupling 2. Shunt peaking 3. Series peaking 4. Input-signal developing 1-47. What is the purpose of C4 in relation to Q2? 1. Decoupling (Bypass) 2. Shunt peaking 3. Series peaking 4. Input-signal developing 1-48. What is the purpose of R4 in relation to Q1? 1. Coupling resistor 2. Input-signal developing 3. Low-frequency compensation 4. High-frequency compensation 1-49. What is the purpose of L4 in relation to Q2? 1. Coupling 2. Decoupling 3. Shunt peaking 4. Series peaking 1-50. What is the purpose of R10 in relation to Q2?

1. Swamping 2. Input-signal developing 3. Low-frequency compensation 4. High-frequency compensation 1-51. Which of the following components is/are used for high-frequency compensation for Q2? 1. C4 2. L3 3. R9 4. All of the above 1-52. Which of the following components is/are used for low-frequency compensation for Q1? 1. C1 2. C2 3. R3 4. All of the above 1-53. What is the effect of the gain of an amplifier if the input-signal developing impedance is decreased? 1. It decreases 2. It increases 3. It remains the same 4. It cannot be determined 7 1-54. What is the effect on the gain of an amplifier if the output-signal-developing impedance is increased?

1. It decreases 2. It increases 3. It remains the same 4. It cannot be determined 1-55. What is/are the purpose(s) of a frequency-determining network in an rf amplifier? 1. To create a large bandpass 2. To compensate for low-frequency losses 3. To provide maximum impedance at a given frequency 4. All of the above 1-56. Of the following networks, which could be used as a frequency-determining network for an rf amplifier? 1. A parallel-resistor network 2. A series-resistor network 3. A parallel RC network 4. A parallel LC network 1-57. Which of the following methods may be used to tune an LRC frequency- determining network to a different frequency?

1. Vary the capacitance 2. Vary the inductance 3. Both 1 and 2 above 4. Vary the resistance 1-58. What is the most common form of coupling for an rf amplifier? 1. RC 2. Resistor 3. Impedance 4. Transformer 1-59. Which of the following advantages are provided by transformer coupling? 1. Simpler power supplies can be used 2. The circuit is not affected by frequency 3. Low-frequency response is improved 4. Fewer parts are used 1-60. If a current gain is desired, which of the following elements/networks should be used as an output-coupling device?

1. An RC network 2. A resistive network 3. A step-up transformer 4. A step-down transformer 1-61. Which of the following techniques would cause a too-narrow bandpass in an rf amplifier? 1. An overcoupled transformer 2. A loosely coupled transformer 3. The use of a swamping resistor 4. The use of a frequency-determining network 1-62. Which of the following techniques would cause low gain at the center frequency of an rf amplifier? 1. An overcoupled transformer 2. A loosely coupled transformer 3. The use of a swamping resistor 4. The use of a frequency-determining network 1-63. What type of transformer coupling should be used in an rf amplifier?

1. Ideal 2. Loose 3. Optimum 4. Overcoupling 8 1-64. Which of the following methods provides the widest band-pass in an rf amplifier? 1. A swamping resistor 2. A loosely coupled amplifier 3. A large input-signal-developing resistor 4. A small output-signal-developing resistor 1-65. Which of the following methods will compensate for the problem that cause low gain in an rf amplifier? 1. Using rf transformers 2. Taking advantage of the interelectrode capacitance 3. Both 1 and 2 above 4. Using audio transformers 1-66. Which of the following types of feedback is usually caused by the base-to-collector interelectrode capacitance?

1. Regenerative 2. Decoupled 3. Positive 4. Negative 1-67. In an rf amplifier an unwanted signal is coupled through the base-to-collector interelectrode capacitance. This problem can be solved by providing feedback out of phase with the unwanted signal. What is this technique called? 1. Neutralization 2. Compensating 3. Decoupling 4. Swamping

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Figure 1C.—RF amplifier.

In Answering Questions 1-68

Through 1-75, Refer To Figure 1C.

1-68. Which of the following components is/are part of the input-signal-developing impedance for Q1? 1. C1 2. T1 3. C3 4. All of the above 1-69. What is the purpose of R1? 1. To provide swamping for the secondary of T1 2. To act as an output-signal-developing resistor 3. To provide proper bias to the base of Q1 4. To develop the signal coupled by C3 1-70. What is the purpose of R2? 1. To provide swamping for C4 2. To develop the input signal for Q1 3. To provide bias to the emitter of Q1 4. To act as the output-signal- developing resistor 1-71. If C4 were removed from the circuit, what would happen to the output?

1. It would increase 2. It would decrease 3. It would remain the same 4. It cannot be determined 9 1-72. Which of the following components is/are part of the load for Q1? 1. C6 2. T2 3. Both 1 and 2 above 4. C3 1-73. How many tuned parallel LC circuits are shown in the schematic? 1. One 2. Two 3. Three 4. Four 1-74. What do the dotted lines connecting C1, C2, C5, and C6 indicate? 1. The components are in a different physical location 2. That the components are "phantom" components 3. The components are variable capacitors 4. The components are ganged together 1-75. What is the purpose of C3?

1. To couple the input signal of Q1 to the secondary of T2 2. To tune the parallel LC circuit of C3, C6, and T2 3. To provide neutralization for Q1 4. To bypass R1 10

Assignment 2

Textbook assignment: Chapter 3, “Special Amplifiers,” pages 3-1 through 3-70. _________________________________________________________________________________ 2-1. What is the maximum number of possible inputs in a differential amplifier? 1. One 2. Two 3. Three 4. Four 2-2. What is the maximum number of possible outputs in an differential amplifier? 1. One 2. Two 3. Three 4. Four Figure 2A.—Difference amplifier.

In Answering Questions 2-3

Through 2-10, Refer To Figure 2A

AND THE FOLLOWING INFORMATION:

The Amplifier Has A Gain Of 6 And

The Input Signals Are Sine Waves

Which Are Equal In Amplitude And

VARY BETWEEN +2 VOLTS AND -2 VOLTS. 2-3. If the input signals are in phase with each other, what will the peak-to-peak amplitude of the output signal be? 1. 0 volts 2. 12 volts 3. 24 volts 4. 48 volts 2-4. Which of the following statements describes the output signal if the input signals are in phase with each other? 1. A sine wave in phase with the input signals 2. A sine wave 180 degrees out of phase with the input signals 3. A sine wave 90 degrees out of phase with the input signals 4. Not a sine wave 2-5. If the input signals are 180 degrees out of phase with each other, what will the peak-to-peak amplitude of the output signal be?

1. 0 volts 2. 12 volts 3. 24 volts 4. 48 volts 2-6. Which of the following statements describes the output signal if the input signals are 180 degrees out of phase with each other? 1. A sine wave 90 degrees out of phase with each input signal 2. A sine wave in phase with input signal number one 3. A sine wave in phase with input signal number two 4. Not a sine wave 11 2-7. If input signal number one is 90 degrees out of phase with input signal number two, what will the peak-to-peak amplitude of the output signal be?

1. 0 volts 2. 12 volts 3. 24 volts 4. 48 volts 2-8. Which of the following statements describes the output signal if input signal number one is 90 degrees out of phase with input signal number two? 1. A sine wave 90 degrees out of phase with input number two 2. A sine wave 180 degrees out of phase with input number one 3. A sine wave 180 degrees out of phase with input number two 4. Not a sine wave 2-9. If input number two is the only input signal applied to the amplifier, what will the peak-to-peak amplitude of the output signal be?

1. 0 volts 2. 12 volts 3. 24 volts 4. 48 volts 2-10. Which of the following statements describes the output signal if input number two is the only input signal applied to the amplifier? 1. A sine wave in phase with the input signal 2. A sine wave 90 degrees out of phase with the input signal 3. A sine wave 180 degrees out of phase with the input signal 4. Not a sine wave Figure 2B.—Differential amplifier.

In Answering Questions 2-11

Through 2-24, Refer To Figure 2B

AND THE FOLLOWING INFORMATION:

All Input Signals Are Sine Waves

With A Peak-To-Peak Amplitude Of 5

Millivolts. The Gain Of The

Amplifier Is 100.

2-11. If input number one and output number one are the only terminals used, what will the peak-to-peak amplitude of the output signal be? 1. 1 volt 2. 2 volts 3. 500 millivolts 4. 0 volt 2-12. Which of the following statements describes the output signal if input number one, and output number one are the only terminals used? 1. A sine wave in phase with the input signal 2. A sine wave 90 degrees out of phase with the input signal 3. A sine wave 180 degrees out of phase with the input signal 4. Not a sine wave 12 2-13. If input number one is the only input and both output terminals are used, what will the peak-to-peak amplitude of each output signal be? (Assume base of Q2 grounded) 1. 1 volt 2. 2 volts 3. 500 millivolts 4. 0 volts 2-14. If input one is the only input used and an output signal is taken between output number one and output number two, what will the peak-to-peak amplitude of the output signal be? (Assume base of Q2 grounded) 1. 1 volt 2. 2 volts 3. 500 millivolts 4. 0 volts 2-15. Which of the following statements describes the output signal if input one is the only input used and an output signal is taken between output number one and output number two?

1. A sine wave twice the amplitude of output number two 2. A sine wave 90 degrees out of phase with the input signal 3. A sine wave one-half the amplitude of output number one 4. Not a sine wave 2-16. If the input signals are in phase with each other what will the amplitude of each output signal be? 1. 1 volt 2. 2 volts 3. 500 millivolts 4. 0 volts 2-17. If the input signals are in phase with each other and an output signal is taken between the two output terminals, what will the amplitude of the output signal be? 1. 1 volt 2. 2 volts 3. 500 millivolts 4. 0 volts 2-18. Which of the following statements describes output signal number one if the input signals are in phase with each other?

1. A sine wave in phase with input signal number one 2. A sine wave in phase with input signal number two 3. A sine wave 90 degrees out of phase with input signal number one 4. Not a sine wave 2-19. If the input signals are 180 degrees out of phase with each other, what will the peak-to-peak output of each output signal be? 1. 1 volt 2. 2 volts 3. 500 millivolts 4. 0 volts 2-20. If the input signals are 180 degrees out of phase with each other and the output signal is taken between the two output terminals, what will the peak-to-peak amplitude of the output signal be?

1. 1 volt 2. 2 volts 3. 500 millivolts 4. 0 volts 13 2-21. Which of the following statements describes output signal number one if the input signals are 180 degrees out of phase with each other? 1. A sine wave in phase with input signal number one 2. A sine wave in phase with input signal number two 3. A sine wave in phase with output signal number two 4. Not a sine wave 2-22. Which of the following statements describes the output signal if the input signals are 180 degrees out of phase with each other and the output signal is taken between the output terminals?

1. A sine wave 2. Not a sine wave 3. A sine wave 90 degrees out of phase with input signal number one 4. A sine wave in phase with input signals number one and two 2-23. If the input amplitudes are increased to 15 millivolts and are 180 degrees out of phase, what will be the peak-to-peak amplitude of the combined output? 1. 1 volt 2. 2 volts 3. 3 volts 4. 1.5 volts 2-24. What will be the peak-to-peak amplitude of the combined output if the inputs are 6 millivolts peak-to-peak, 180 degrees out of phase, and the gain is 20?

1. 2 volts 2. 2.4 volts 3. 0.12 volts 4. 0.24 volts 2-25. Which of the following is NOT a requirement for an operational amplifier? 1. Very high gain 2. Very high input impedance 3. Very high output impedance 4. Very low output impedance 2-26. Which of the following types of components are used in most operational amplifiers? 1. Transistor circuits 2. Electron tube circuits 3. Both 1 and 2 above 4. Integrated circuits

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14 Figure 2C.—Operational Amplifier.

In Answering Questions 2-27

Through 2-29, Refer To Figure 2C.

2-27. What is part A of the figure? 1. An input amplifier 2. A power amplifier 3. A voltage amplifier 4. A differential amplifier 2-28. What is part B of the figure? 1. A differential amplifier 2. A voltage amplifier 3. A power amplifier 4. A video amplifier 2-29. What is part C of the figure? 1. An output amplifier 2. A voltage amplifier 3. A differential amplifier 4. A high-impedance amplifier 2-30. If degenerative feedback is used in an operational-amplifier circuit, which of the following terms describes the circuit configuration?

1. Open loop 2. Closed loop 3. Full circle 4. Neutralized 2-31. Which of the following signals determines the stability of the output signal from an operational-amplifier circuit in which degenerative feedback is used? 1. The input signal only 2. The feedback signal only 3. Both 1 and 2 above 4. The detected signal

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15 Figure 2D.—Inverting Configuration.

In Answering Questions 2-32

Through 2-36, Refer To Figure 2D.

2-32. In the inverting configuration of an operational-amplifier circuit where are the (a) input signal and (b) feedback signal applied? 1. (a) Inverting input (b) Inverting input 2. (a) Inverting input (b) Noninverting input 3. (a) Noninverting input (b) Inverting input 4. (a) Noninverting input (b) Noninverting input 2-33. In the inverting configuration of an operational-amplifier circuit with feedback applied and a 1-volt, peak-to- peak, sine wave as an input signal, what is the amplitude of the signal at the inverting input of the operational amplifier?

1. 1 volt 2. 2 volts 3. 10 volts 4. 0 volts 2-34. In the inverting configuration of an operational-amplifier circuit, when the noninverting input of the operational amplifier is grounded, what is the term that describes the potential at the inverting input of the operational amplifier? 1. Feedback-signal voltage 2. Input-signal voltage 3. Signal ground 4. Virtual ground 2-35. If the amplitude of the input signal to the circuit is +2 millivolts, what will the amplitude of the output signal be? 1. -10 mV 2. -2 mV 3. +10 mv 4. +2 mV 2-36. If the unity gain point of the operational amplifier is 1 mega-hertz, what is the bandwidth of the circuit?

1. 100 kHz 2. 200 kHz 3. 300 kHz 4. 400 kHz

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16 Figure 2E.—Noninverting Configuration.

In Answering Questions 2-37 And

2-38, REFER TO FIGURE 2E. 2-37. If the amplitude of the input signal is +10 millivolts, what is the amplitude of the output signal? 1. +70 mV 2. +60 mV 3. -70 mV 4. -60 mV 2-38. The open-loop gain of the operational amplifier is 100,000 and the open-loop bandwidth is 10 hertz. If we make it a closed-loop with a gain of 10, what is the bandwidth of the circuit? 1. 100 kHz 2. 350 kHz 3. 500 kHz 4. 583 kHz 2-39. Which of the following is a difference between a summing amplifier and an adder circuit? 1. The amount of gain 2. The number of inputs 3. The type of operational amplifier 4. The placement of resistors in the circuit Figure 2F.—Scaling Amplifier.

In Answering Questions 2-40 And

2-41, REFER TO FIGURE 2F. 2-40. THIS QUESTION HAS BEEN DELETED. 2-41. If the amplitude of the signal at E1 is +3 volts and the amplitude of the signal at E2 is +4 volts, what is the amplitude of the output signal? 1. +39 volts 2. +45 volts 3. -39 volts 4. -45 volts 2-42. If the amplitude of the signal at E1 is +5 volts and the amplitude of the signal at E2 is +2 volts, what is the amplitude of the signal at the inverting (-) input of the operational amplifier? 1. 0 volts 2. +7 volts 3. +21 volts 4. +54 volts 2-43. Which of the following is a difference between a difference amplifier and a subtractor?

1. The amount of gain 2. The number of inputs 3. The type of operational amplifier 4. The placement of resistors in the circuit 17 2-44. How many inputs can a (a) difference amplifier and (b) summing amplifier have? 1. (a) Two only (b) Two only 2. (a) Two only (b) More than two 3. (a) More than two (b) Two only 4. (a) More than two (b) More than two Figure 2G.—Difference Amplifier.

In Answering Questions 2-45

Through 2-48, Refer To Figure 2G.

2-45. THIS QUESTION HAS BEEN DELETED. 2-46. If the amplitude of the signal at E1 is +3 volts and the amplitude of the signal at E2 is +9 volts, what will the amplitude of the output signal be? 1. +6 volts 2. +12 volts 3. +30 volts 4. +60 volts 2-47. If the amplitude of the signal at E1 is +6 volts and the amplitude of the signal at E2 is +2 volts, what will the amplitude of the output signal be? 1. +8 volts 2. +20 volts 3. -20 volts 4. -40 volts 2-48. The gain of the operational amplifier shown in figure 2G can be determined by using the ratio of resistance. Which of the following ratios is correct for determining this gain.

1. 3. 2. 4. 2-49. A magnetic amplifier can be classified as which of the following types of amplifier? 1. RF amplifier 2. Audio amplifier 3. Video amplifier 4. Voltage amplifier 2-50. Which of the following statements describes the basic operating principle of a magnetic amplifier? 1. Any power amplifier will create a magnetic field which can be used to increase the gain of the power amplifier 2. The inductance of an air-core inductor will change as the power used by the load changes 3. A changing inductance can be used to control the current in a load 4. Magnetism can be increased (amplified) by changing the voltage amplitude 2-51. What happens to the true power in a series LR circuit if the inductance is decreased?

1. It increases 2. It decreases 3. It remains the same 4. It increases initially and then decreases rapidly 18 2-52. If the permeability of the core of a coil decreases, what happens to the (a) inductance and (b) true power in the circuit? 1. (a) Increases (b) increases 2. (a) Increases (b) decreases 3. (a) Decreases (b) increases 4. (a) Decreases (b) decreases 2-53. If the current in an iron-core coil is increased to a large value (from the operating point) what happens to the permeability of the core? 1. It increases 2. It decreases 3. It remains the same 4. It increases initially and then decreases rapidly 2-54. If two coils are wound on a single iron core, a change in current in one coil (a) will or will not cause a change in inductance and (b) will or will not cause a change in current in the other coil.

1. (a) Will (b) will 2. (a) Will (b) will not 3. (a) Will not (b) will 4. (a) Will not (b) will not Figure 2H.—Saturable-core reactor.

In Answering Question 2-55, Refer

To Figure 2H.

2-55. What portion of the schematic diagram indicates a saturable core? 1. a 2. b 3. c 4. d 2-56. A magnetic amplifier should be operated on what portion of the magnetization curve? 1. The positive peak 2. The negative peak 3. The mid-point 4. The knee 2-57. A toroidal core is used in a saturable-core reactor to counteract which of the following effects? 1. Hysteresis 2. Copper loss 3. Both 1 and 2 above 4. The effect of load flux on control flux 2-58. Why is a rectifier used in a magnetic amplifier? 1. To decrease current 2. To eliminate hysteresis loss 3. To increase the power-handling capability 4. To convert the magnetic amplifier from an a.c. device to a d.c. device.

2-59. What can be used to set a magnetic amplifier to the proper operating point and leave the control winding free to accept input signals? 1. A filter 2. A bias winding 3. A d.c. power source 4. A feedback network 2-60. A magnetic amplifier would not be used in which of the following devices? 1. A servo system 2. A d.c. power supply 3. Temperature indicators 4. A wideband audio power amplifier system