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Home Digital Electronics Multivibrators and 555 Timer Comments

  • Question
  • When the 74123, a retriggerable monostable multivibrator device, ends its timing cycle it must be started all over again.


  • Options
  • A. True
  • B. False

  • Correct Answer
  • False 


  • Multivibrators and 555 Timer problems


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    • 1. A comparator simply outputs a HIGH or LOW based on a comparison of the voltage levels at its input.

    • Options
    • A. True
    • B. False
    • Discuss
    • 2. When extremely critical timing is required, a quartz crystal can be used.

    • Options
    • A. True
    • B. False
    • Discuss
    • 3. In the 74121, which is nonretriggerable, any triggers that come in before the end of the timing cycle are ignored.

    • Options
    • A. True
    • B. False
    • Discuss
    • 4. A single Schmitt trigger inverter is all that is needed to build a simple astable multivibrator.

    • Options
    • A. True
    • B. False
    • Discuss
    • 5. The bistable multivibrator is an R-C flip-flop.

    • Options
    • A. True
    • B. False
    • Discuss
    • 6. Timing accuracy of more than eight significant digits can be easily achieved by using quartz crystals.

    • Options
    • A. True
    • B. False
    • Discuss
    • 7. The 74S124 TTL chip is a voltage-controlled oscillator that will generate a specific frequency at Vout.

    • Options
    • A. True
    • B. False
    • Discuss
    • 8. A multivibrator is a circuit that changes between two digital levels on a continuous, free-running basis or on demand.

    • Options
    • A. True
    • B. False
    • Discuss
    • 9. A monostable multivibrator is commonly called a two shot.

    • Options
    • A. True
    • B. False
    • Discuss
    • 10. The 8051 is a 40-pin IC. Twenty-two pins are needed for the four I/O ports.

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


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