85. In a phase shift oscillator, the frequency determining elements are
A. L and C
B. R, Land C
C. R and C
D. none of the above

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86. A wien bridge oscillator uses ____ feedback.
A. only positive
B. only negative both positive and negative
C. none of the above
D.

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87. The piezoelectric effect in a crystal is
A. a voltage developed because of mechanical stress
B. a change in resistance because of temperature
C. a change of frequency because of temperature
D. none of the above

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88.  If the crystal frequency changes with temperature, we say that crystal has _____ temperature coefficient.
A. positive
B. zero
C. negative
D. none of the above

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89. The crystal oscillator frequency is very stable due to of the crystal.
A. rigidity
B. vibrations
C. low Q
D. high Q

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90. The application where one would most likely find a crystal oscillator is
A. radio receiver
B. radio transmitter
C. AF sweep generator
D. none of the above

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91. An oscillator differs from an amplifier because it
A. has more gain
B. requires no input signal
C. requires no d.c. supply
D. always has the same input

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