86. An amplifier is stable if the absolute magnitude of A is ________.
(a)
(b) less than 1
(c) greater than 1
(d) None of the above
87. Nota
88. In a Hartley oscillator, the elements X1 and X2 are ________ and X3 is a(n) ________.
(a) inductors, capacitor
(b) capacitors, inductor
(c) capacitors, resistor
(d) inductors, resistor
89. Voltage feedback connections tend to ________ the output impedance. Current feedback connections tend to ________ the output impedance.
(a) decrease, increase
(b) increase, decrease
(c) increase, increase
(d) decrease, decrease
90. Negative feedback results in ________.
(a) decreased voltage gain
(b) increased voltage gain
(c) oscillation in the circuit
(d) None of the above
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Oscillators » Exercise - 1 1. For generating 1 kHz signal, the most suitable circuit is : (a) colpitts oscillator (b) hartley oscillator (c) tuned collector oscillator (d) wien bridge oscillator 2. The feedback factor β at the frequency of oscillation of a Wien bridge oscillator is : (a) 3 (b) 1/3 (c) 1/29 (d) 3/29 3. The use of crystal in a tunable oscillator : (a) improves frequency stability (b) increases the gain of the oscillator (c) helps to obtain optimum output impedance (d) facilitates generation of wide range of frequencies 4. A phase shift oscillator uses : (a) LC tuning (b) piezoelectric crystal (c) balanced bridge (d) variable frequency operation 5. A highly stable resonance characteristic is the property of a …….. oscillator. (a) hartley (b) colpitts (c) crystal (d) wein bridge 6. The main advantage of a crystal oscillator is that its output is : (a) 50Hz to 60Hz (b) variable frequency (c) a constant frequency (d) direct current 7. An oscillator of the LC type that has a split capacitor in the circuit is : (a) hartley oscillator (b) colpitts oscillator (c) wein bridge oscillator (d) R-C phase shift oscillator 8. Wein bridge oscillator can typically generate frequencies in the range of : (a) 1KHz…- 5555555555 69. Determine the voltage gain with feedback for a voltage-series feedback having A = –100, R1 = 15 kΩ, R0 = 20 kΩ, and a feedback of β = –0.25. (a) 3.85 (b) –3.85 (c) –9.09 (d) 9.09
- Amplifiers » Exercise - 17. Negative feedback in an amplifier : (a) reduces the voltage gain (b) increases the voltage gain (c) does not affect the voltage gain (d) converts the amplifier into an oscillator
- 555555555551. In order to sustain oscillations in a feedback oscillator, the gain should be _________ so the Acl _______. (a) reduced, equals one (b) reduced, is less than one (c) increased, is more than one (d) increased, is much greater than one
- 5555555555 58. The attenuation of the three-section RC feedback phase-shift oscillator is ________. (a) 1/9. (b) 1/30. (c) 1/3. (d) 1/29.