Multivibrators and 555 Timer

MCQsQuestion.com has 29 Question/Answers about Topic Multivibrators and 555 Timer

With most monostable multivibrators, what is the Q output when no input trigger has occurred?

With most monostable multivibrators, what is the Q output when no input trigger has occurred?
  • A. LOW
  • B. +5 V
  • C. SET
  • D. HIGH
  • Correct Answer: Option A

If a diode is connected across resistor RB

If a diode is connected across resistor RB
  • A. 56%
  • B. 44%
  • C. 21.6%
  • D. 17.4%
  • Correct Answer: Option C

If Vcc

If Vcc
  • A. VOH = 10 V, VOL = 0 V
  • B. VOH = 10 V, VOL = 0.1 V
  • C. VOH = 8.5 V, VOL = 0 V
  • D. VOH = 8.5 V, VOL = 0.1 V
  • Correct Answer: Option D

What does the discharge transistor do in the 555 timer circuit?

What does the discharge transistor do in the 555 timer circuit?
  • A. charge the external capacitor to stop the timing
  • B. charge the external capacitor to start the timing over again
  • C. discharge the external capacitor to stop the timing
  • D. discharge the external capacitor to start the timing over again
  • Correct Answer: Option D

What is the function of the comparators in the 555 timer circuit?

What is the function of the comparators in the 555 timer circuit?
  • A. to compare the output voltages to the internal voltage divider
  • B. to compare the input voltages to the internal voltage divider
  • C. to compare the output voltages to the external voltage divider
  • D. to compare the input voltages to the external voltage divider
  • Correct Answer: Option B

A crystal demonstrates the ________ effect when a mechanical force across the crystal causes a small voltage to be generated.

A crystal demonstrates the ________ effect when a mechanical force across the crystal causes a small voltage to be generated.
  • A. photoelectric
  • B. Co-pitts
  • C. piezoelectric
  • D. flywheel
  • Correct Answer: Option C

Which mode of operation is being used when a 555 timer chip has two external resistors and an external capacitor?

Which mode of operation is being used when a 555 timer chip has two external resistors and an external capacitor?
  • A. monostable
  • B. pulse stretching
  • C. Schmitt triggering
  • D. astable
  • Correct Answer: Option D

The internal circuitry of the 555 timer consists of ________, an R-S flip-flop, a transistor switch, an output buffer amplifier, and a voltage divider.

The internal circuitry of the 555 timer consists of ________, an R-S flip-flop, a transistor switch, an output buffer amplifier, and a voltage divider.
  • A. a comparator
  • B. a voltage amplifier
  • C. two comparators
  • D. a peak detector
  • Correct Answer: Option C

What is the pulse width of the output of a 74123 if an external 4.7-k resistor and a 0.022-F capacitor are used?

What is the pulse width of the output of a 74123 if an external 4.7-k resistor and a 0.022-F capacitor are used?
  • A. 290 ms
  • B. 29 ms
  • C. 33.3 s
  • D. 290 s
  • Correct Answer: Option C

Triggering a retriggerable one shot during pulse generation will:

Triggering a retriggerable one shot during pulse generation will:
  • A. time out the original pulse
  • B. extend the pulse to this trigger width
  • C. have no effect
  • D. double the original pulse width
  • Correct Answer: Option B

A retriggerable one shot has a pulse of 10 ms. 3 ms after being triggered, another trigger pulse is applied. The resulting output pulse will be ________ ms.

A retriggerable one shot has a pulse of 10 ms. 3 ms after being triggered, another trigger pulse is applied. The resulting output pulse will be ________ ms.
  • A. 3
  • B. 7
  • C. 10
  • D. 13
  • Correct Answer: Option D

Which of the following is NOT a characteristic of a retriggerable monostable multivibrator?

Which of the following is NOT a characteristic of a retriggerable monostable multivibrator?
  • A. It is a dual multivibrator.
  • B. It has an active-HIGH reset, which terminates all timing functions.
  • C. It has no internal timing resistor.
  • D. none of the above
  • Correct Answer: Option B

What is the difference between a retriggerable one shot and a nonretriggerable one shot?

What is the difference between a retriggerable one shot and a nonretriggerable one shot?
  • A. The nonretriggerable can only be triggered once.
  • B. The retriggerable can be triggered many times.
  • C. The output pulse can be stretched with a nonretriggerable.
  • D. The output pulse can be stretched with a retriggerable.
  • Correct Answer: Option D

Design a circuit using a 74121 to convert a 33-kHz, 30% duty cycle waveform to a 33-kHz, 60% duty cycle waveform.

Design a circuit using a 74121 to convert a 33-kHz, 30% duty cycle waveform to a 33-kHz, 60% duty cycle waveform.
  • A. Rint = 2 k, Cext = 0.012 nF
  • B. Rint = 2 k, Cext = 0.012 F
  • C. Rint = 4 k, Cext = 0.012 nF
  • D. Rint = 4 k, Cext = 0.012 F
  • Correct Answer: Option B

Pulse stretching, time-delay, and pulse generation are all easily accomplished with which type of multivibrator circuit?

Pulse stretching, time-delay, and pulse generation are all easily accomplished with which type of multivibrator circuit?
  • A. astable
  • B. monostable
  • C. multistable
  • D. bistable
  • Correct Answer: Option B
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