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

  • 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

  • Correct Answer
  • astable 

    • Multivibrators and 555 Timer problems

    Search Results

    • 1. 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
    • 2. 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
    • 3. 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
    • 4. An astable 555 timer has the following number of stable states:

    • Options
    • A. 0
    • B. 1
    • C. 2
    • D. 3
      • Discuss
    • 5. Determine tHI and tLO for the circuit given below.


    • Options
    • A. tHI = 7.95 µs, tLO = 6.24 µs
    • B. tHI = 6.24 µs, tLO = 7.95 µs
    • C. tHI = 3.97 µs, tLO = 3.21 µs
    • D. tHI = 3.21 µs, tLO = 3.97 µs
      • Discuss
    • 6. 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
    • 7. 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
    • 8. 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
    • 9. Is the circuit given below an astable multivibrator or a monostable multivibrator?


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

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