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Home Digital Electronics Multivibrators and 555 Timer Comments

  • Question
  • The output of the astable circuit ________.


  • Options
  • A. constantly switches between two states
  • B. is LOW until a trigger is received
  • C. is HIGH until a trigger is received
  • D. floats until triggered

  • Correct Answer
  • constantly switches between two states 


  • Multivibrators and 555 Timer problems


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

    • Options
    • A. LOW
    • B. +5 V
    • C. SET
    • D. HIGH
    • Discuss
    • 2. Which of the following is NOT a characteristic of a retriggerable monostable multivibrator?

    • Options
    • 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
    • Discuss
    • 3. What is the difference between a retriggerable one shot and a nonretriggerable one shot?

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

    • Options
    • A. astable
    • B. monostable
    • C. multistable
    • D. bistable
    • Discuss
    • 5. A monostable 555 timer has the following number of stable states:

    • Options
    • A. 0
    • B. 1
    • C. 2
    • D. 3
    • Discuss
    • 6. When a capacitor charges:

    • Options
    • A. the voltage across the plates rises exponentially
    • B. the circuit current falls exponentially
    • C. the capacitor charges to the source voltage in 5×RC seconds
    • D. all of the above
    • Discuss
    • 7. The pulse width out of a one-shot multivibrator increases when the:

    • Options
    • A. supply voltage increases
    • B. timing resistor decreases
    • C. UTP decreases
    • D. timing capacitance increases
    • Discuss
    • 8. What is another name for a bistable multivibrator?

    • Options
    • A. an on-off switch
    • B. an oscillator
    • C. a flip-flop
    • Discuss
    • 9. A 0.3-µF capacitor has an initial charge of 2.7 V. If it is discharged through a 10-kΩ resistor for 6.5 ms, how much voltage will be left across the capacitor?

    • Options
    • A. 0.0 V
    • B. 0.309 V
    • C. 2.7 V
    • D. 2.295 V
    • Discuss
    • 10. This program code will be executed once:

      STAT: MOV A, #01H
        JNZ STAT

    • Options
    • A. True
    • B. False
    • Discuss


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