NEETS MODULE 8 CHAPTER 1 AMPLIFIERS
Q-1. What is amplification?
Q-2. Does an amplifier actually change an input signal? Why or why not?
Q-3. Why do electronic devices use amplifiers?
Q-4. In what two ways are amplifiers classified?
Q-5. What type of amplifier would be used to drive the speaker system of a record player?
Q-6. What type of amplifier would be used to amplify the signal from a radio antenna?
Q-7. What determines the class of operation of an amplifier?
Q-8. What are the four classes of operation of a transistor amplifier?
Q-9. If the output of a circuit needs to be a complete representation of one-half of the input signal,what class of operation is indicated?
Q-10. Why is class C operation more efficient than class A operation?
Q-11. What class of operation has the highest fidelity?
Q-12. What is the purpose of an amplifier-coupling network?
Q-13. What are four methods of coupling amplifier stages?
Q-14. What is the most common form of coupling?
Q-15. What type coupling is usually used to couple the output from a power amplifier?
Q-16. What type coupling would be most useful for an audio amplifier between the first and secondstages?
Q-17. What type of coupling is most effective at high frequencies?
Q-18. What impedance relationship between the output of one circuit and the input of another circuitwill provide the maximum power transfer?
Q-19. If maximum current is desired at the input to a circuit, should the input impedance of that circuitbe lower than, equal to, or higher than the output impedance of the previous stage?
Q-20. What are the input- and output-impedance characteristics of the three transistor configurations?
Q-21. What transistor circuit configuration should be used to match a high output impedance to a lowinput impedance?
Q-22. What type of coupling is most useful for impedance matching?
Q-23. What is feedback?
Q-24. What are the two types of feedback?
Q-25. What type feedback provides increased amplitude output signals?
Q-26. What type feedback provides the best fidelity?
Q-27. If the feedback signal is out of phase with the input signal, what type feedback is provided?
Q-28. What type feedback is provided by an unbypassed emitter resistor in a common-emittertransistor amplifier?
Q-29. What is a phase splitter?
Q-30. What is one use for a splitter?
Q-31. What is a common use for a push-pull amplifier?
Q-32. What is the advantage of a push-pull amplifier?
Q-33. What class of operation can be used with a push-pull amplifier to provide good fidelity outputsignals?
NEETS MODULE 8 CHAPTER 2 VIDEO AND RF AMPLIFIERS
Q-1. What is the bandwidth of an amplifier?
Q-2. What are the upper and lower frequency limits of an amplifier?
Q-3. What are the upper and lower frequency limits and the bandwidth for the amplifiers that havefrequency-response curves as shown in figure 2-3?
Q-4. What are the factors that limit the frequency response of a transistor amplifier?
Q-5. What type of feedback is usually caused by interelectrode capacitance?
Q-6. What happens to capacitive reactance as frequency increases?
Q-7. What happens to inductive reactance as frequency increases?
Q-8. What is the major factor that limits the high-frequency response of an amplifier circuits?
Q-9. What components can be used to increase the high-frequency response of an amplifier?
Q-10. What determines whether these components are considered series or shunt?
Q-11. What is the arrangement of both series and shunt components called?
Q-12. What component in an amplifier circuit tends to limit the low-frequency response of the amplifier?
Q-13. What is the purpose of L3?
Q-14. What is the purpose of C1?
Q-15. What is the purpose of R4?
Q-16. What is the purpose of L2?
Q-17. What is the purpose of R5?
Q-18. What component(s) is/are used for high-frequency compensation for Q1?
Q-19. What component(s) is/are used for low-frequency compensation for Q2?
Q-20. If the input-signal-developing impedance of an amplifier is increased, what is the effect on thegain?
Q-21. If the output impedance of an amplifier circuit is decreased, what is the effect on the gain?
Q-22. What is the purpose of a frequency-determining network in an rf amplifier?
Q-23. Can a parallel LC circuit be used as the frequency-determining network for an rf amplifier?
Q-24. How can the frequency be changed in the frequency-determining network?
Q-25. What is the most common form of coupling for an rf amplifier?
Q-26. What are two advantages of this type of coupling?
Q-27. If current gain is required from an rf amplifier, what type of component should be used as anoutput coupling element?
Q-28. What problem is caused in an rf amplifier by a loosely coupled transformer?
Q-29. How is this problem corrected?
Q-30. What problem is caused by overcoupling in a transformer?
Q-31. What method provides the widest bandpass?
Q-32. What two methods are used to compensate for the problems that cause low gain in an rf amplifier?
Q-33. What type of feedback is usually caused by the base-to-collector interelectrode capacitance?
Q-34. How is this compensated for?
Q-35. What components form the input-signal-developing impedance for the amplifier?
Q-36. What is the purpose of R1?
Q-37. What is the purpose of R2?
Q-38. If C4 were removed from the circuit, what would happen to the output of the amplifier?
Q-39. What components form the load for Q1?
Q-40. How many tuned parallel LC circuits are shown in this schematic?
Q-41. What do the dotted lines connecting C1, C2, C5, and C6 indicate?
Q-42. What is the purpose of C3?
NEETS MODULE 8 CHAPTER 3 SPECIAL AMPLIFIERS
Q-1. How many inputs and outputs are possible with a differential amplifier?
Q-2. What two transistor amplifier configurations are combined in the single-transistor, two-input,single-output difference amplifier?
Q-3. If the two input signals of a difference amplifier are in phase and equal in amplitude, what willthe output signal be?
Q-4. If the two input signals to a difference amplifier are equal in amplitude and 180 degrees out ofphase, what will the output signal be?
Q-5. If only one input signal is used with a difference amplifier, what will the output signal be?
Q-6. If the two input signals to a difference amplifier are equal in amplitude but neither in phase nor180 degrees out of phase, what will the output signal be?
Q-7. If the differential amplifier is configured with a single input and a single output, what will thepeak-to-peak amplitude of the output signal be?
Q-8. If the differential amplifier is configured with a single input and differential outputs, what willthe output signals be?
Q-9. If the single-input, differential-output, differential amplifier has an output signal taken betweenthe two output terminals, what will the peak-to-peak amplitude of this combined output be?
Q-10. If the input signals are in phase, what will be the peak-to-peak amplitude of the output signals?
Q-11. If the input signals are 180 degrees out of phase with each other, what will be the peak-to-peakamplitude of the output signals?
Q-12. If the input signals are 180 degrees out of phase with each other, what will the phaserelationship be between (a) the output signals and (b) the input and output signals?
Q-13. If the input signals are 180 degrees out of phase with each other and a combined output is takenbetween the two output terminals, what will the amplitude of the combined output signal be?
Q-14. If the input signals are 90 degrees out of phase with each other and a combined output is takenbetween the two output terminals, (a) what will the peak-to-peak amplitude of the combinedoutput signal be, and (b) will the combined output signal be a sine wave?
Q-15. What are the three requirements for an operational amplifier?
Q-16. What is the most commonly used form of the operational amplifier?
Q-17. Draw the schematic symbol for an operational amplifier
Q-18. Label the parts of the operational amplifier shown in figure 3-12.
Q-19. What does the term "closed-loop" mean in the closed-loop configuration of an operationalamplifier?
Q-20. In a closed-loop configuration the output signal is determined by (the input signal, the feedbacksignal, both).
Q-21. In the inverting configuration, the input signal is applied to the (a) (inverting, noninverting)input and the feedback signal is applied to the (b) (inverting, noninverting) input.
Q-22. In the inverting configuration, what is the voltage (for all practical purposes) at the invertinginput to the operational amplifier if the input signal is a 1-volt, peak-to-peak sine wave?
Q-23. In the inverting configuration when the noninverting input is grounded, the inverting input is at(signal, virtual) ground.
Q-24. In a circuit such as that shown in figure 3-15, if R1 has a value of 100 ohms and R2 has a valueof 1 kilohm and the input signal is at a value of + 5 millivolts, what is the value of the outputsignal?
Q-25. If the unity-gain point of the operational amplifier used in question 24 is 500 kilohertz, what isthe bandwidth of the circuit?
Q-26. In a circuit such as that shown in figure 3-16, if R1 has a value of 50 ohms and R2 has a value of250 ohms and the input signal has a value of +10 millivolts, what is the value of the outputsignal?
Q-27. If the open-loop gain of the operational amplifier used in question 26 is 200,000 and the openloopbandwidth is 30 hertz, what is the closed loop bandwidth of the circuit?
Q-31. What type of circuit is figure 3-27?
Q-32. If: E1 = +2V, and: E2 = +6V, then Eout = ?
Q-33. What is the difference in potential between the inverting (-) and noninverting (+) inputs to theoperational amplifier when: E1 = +6V, and E2 = +2V
Q-34. What is the difference between a subtractor and a difference amplifier?
Q-35. Can a difference amplifier have more than two inputs?
Q-36. What type of circuit is figure 3-28?
Q-37. If: E1 = +5V, and: E2 = +11V, then Eout = ?
Q-38. What is the difference in potential between the inverting (í DQGnoninverting (+) inputs to theoperational amplifier when: E1 = +2V, and E2 = +4V
Q-39. What is the frequency classification of a magnetic amplifier?
Q-40. What is the basic principle of a magnetic amplifier?
Q-41. If inductance increases in a series LR circuit, what happens to true power?
Q-42. If the permeability of the core of a coil increases, what happens to (a) inductance and (b) truepower in the circuit?
Q-43. What happens to the permeability of an iron core as the current increases from the operatingpoint to a large value?
Q-44. If two coils are wound on a single iron core, what will a change in current in one coil cause inthe other coil?
Q-45. What symbol in figure 3-33 indicates a saturable core connecting two windings?
Q-46. At what portion of the magnetization curve should a magnetic amplifier be operated?
Q-47. How is the effect of load flux on control flux eliminated in a saturable-core reactor?
Q-48. What is the purpose of the rectifier in a magnetic amplifier?
Q-49. What is used to bias a magnetic amplifier so that the control winding remains free to acceptcontrol (input) signals?
Q-50. List two common usages of magnetic amplifiers.
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