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Home ‣ Digital Electronics ‣ Multivibrators and 555 Timer Comments
  • Question

  • The monostable multivibrator circuit is not an oscillator because ________.


  • Options
  • A. its output switches between two states
  • B. it requires a trigger to obtain an output signal
  • C. it requires a sine wave input signal
  • D. the circuit does not require a dc power supply

  • Correct Answer
  • it requires a trigger to obtain an output signal 

    • Multivibrators and 555 Timer problems

    Search Results

    • 1. Triggering a retriggerable one shot during pulse generation will:

    • Options
    • A. time out the original pulse
    • B. extend the pulse to this trigger width
    • C. have no effect
    • D. double the original pulse width
      • Discuss
    • 2. A 22-kΩ resistor and a 0.02-µF capacitor are connected in series to a 5-V source. How long will it take the capacitor to charge to 3.4 V?

    • Options
    • A. 0.44 ms
    • B. 0.501 ms
    • C. 0.66 ms
    • D. 0.70 ms
      • Discuss
    • 3. Is the circuit given below an astable multivibrator or a monostable multivibrator?


    • Options
    • A. monostable
    • B. astable
      • Discuss
    • 4. What is the function of the comparators in the 555 timer circuit?

    • Options
    • 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
      • Discuss
    • 5. The ________ is defined as the time the output is active divided by the total period of the output signal.

    • Options
    • A. on time
    • B. off time
    • C. duty cycle
    • D. active ratio
      • Discuss
    • 6. Does the 74123 one shot have an internal timing resistor?

    • Options
    • A. yes
    • B. no
      • Discuss
    • 7. What does the discharge transistor do in the 555 timer circuit?

    • Options
    • 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
      • Discuss
    • 8. What controls the output pulse width of a one shot?

    • Options
    • A. the clock frequency
    • B. the width of the clock pulse
    • C. an RL time constant
    • D. an RC time constant
      • Discuss
    • 9. 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.

    • Options
    • A. a comparator
    • B. a voltage amplifier
    • C. two comparators
    • D. a peak detector
      • Discuss
    • 10. What is the duty cycle of the waveform at the output of the circuit given below?


    • Options
    • A. 78%
    • B. 56%
    • C. 50%
    • D. 44%
      • Discuss

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