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Home Digital Electronics Multivibrators and 555 Timer Comments

  • Question
  • 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

  • Correct Answer
  • an RC time constant 


  • Multivibrators and 555 Timer problems


    Search Results


    • 1. 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
    • 2. Does the 74123 one shot have an internal timing resistor?

    • Options
    • A. yes
    • B. no
    • Discuss
    • 3. 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
    • 4. 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
    • 5. 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
    • 6. 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
    • 7. 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
    • 8. Design a circuit using a 74121 to convert a 33-kHz, 30% duty cycle waveform to a 33-kHz, 60% duty cycle waveform.

    • Options
    • A. Rint = 2 kΩ, Cext = 0.012 nF
    • B. Rint = 2 kΩ, Cext = 0.012 µF
    • C. Rint = 4 kΩ, Cext = 0.012 nF
    • D. Rint = 4 kΩ, Cext = 0.012 µF
    • Discuss
    • 9. What is the pulse width of the output of a 74123 if an external 4.7-kΩ resistor and a 0.022-µF capacitor are used?

    • Options
    • A. 290 ms
    • B. 29 ms
    • C. 33.3 µs
    • D. 290 µs
    • Discuss
    • 10. A monostable 555 timer has the following number of stable states:

    • Options
    • A. 0
    • B. 1
    • C. 2
    • D. 3
    • Discuss


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