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Home Digital Electronics Multivibrators and 555 Timer Comments

  • Question
  • 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

  • Correct Answer
  • duty cycle 


  • Multivibrators and 555 Timer problems


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    • 1. If the resistor in the Schmitt trigger astable multivibrator is a variable resistor, what part of the output voltage waveform will change when the resistance is changed?

    • Options
    • A. the shape of the waveform
    • B. the amplitude of the waveform
    • C. the period of the waveform
    • D. none of the above
    • Discuss
    • 2. Which mode of operation is being used when a 555 timer chip has two external resistors and an external capacitor?

    • Options
    • A. monostable
    • B. pulse stretching
    • C. Schmitt triggering
    • D. astable
    • Discuss
    • 3. 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.

    • Options
    • A. 3
    • B. 7
    • C. 10
    • D. 13
    • Discuss
    • 4. What is the difference between an astable multivibrator and a monostable multivibrator?

    • Options
    • A. The astable is free running.
    • B. The astable needs to be clocked.
    • C. The monostable is free running.
    • D. none of the above
    • Discuss
    • 5. What is the output pulse width of the waveform at the output of the circuit in the given figure?


    • Options
    • A. 1.65 ms
    • B. 18.2 ms
    • C. 4.98 ms
    • D. 54.6 ms
    • Discuss
    • 6. 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
    • 7. Is the circuit given below an astable multivibrator or a monostable multivibrator?


    • Options
    • A. monostable
    • B. astable
    • Discuss
    • 8. 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
    • 9. 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
    • 10. 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
    • Discuss


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