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  • Question

  • The circuit given below fails to function; the inputs are checked with a logic probe and the following indications are obtained: CLK, J1, J2, J3, K1, K2, and K3 are pulsing. Q and The circuit given below fails to function; the inputs are checked with a logic probe and the followi are HIGH. The circuit given below fails to function; the inputs are checked with a logic probe and the followi and PRE are LOW. What could be causing the problem?

    The circuit given below fails to function; the inputs are checked with a logic probe and the followi


  • Options
  • A. There is no problem.
  • B. The clock should be held HIGH.
  • C. The PRE is stuck LOW.
  • D. The CLR is stuck HIGH.

  • Correct Answer
  • The PRE is stuck LOW. 

    • Flip-Flops problems

    Search Results

    • 1. Why are the S and R inputs of a gated flip-flop said to be synchronous?

    • Options
    • A. They must occur with the gate.
    • B. They occur independent of the gate.
      • Discuss
    • 2. On a master-slave flip-flop, when is the master enabled?

    • Options
    • A. when the gate is LOW
    • B. when the gate is HIGH
    • C. both of the above
    • D. neither of the above
      • Discuss
    • 3. How can the cross-coupled NAND flip-flop be made to have active-HIGH S-R inputs?

    • Options
    • A. It can't be done.
    • B. Invert the Q outputs.
    • C. Invert the S-R inputs.
      • Discuss
    • 4. A J-K flip-flop is in a "no change" condition when ________.

    • Options
    • A. J = 1, K = 1
    • B. J = 1, K = 0
    • C. J = 0, K = 1
    • D. J = 0, K = 0
      • Discuss
    • 5. Latches constructed with NOR and NAND gates tend to remain in the latched condition due to which configuration feature?

    • Options
    • A. cross coupling
    • B. gate impedance
    • C. low input voltages
    • D. asynchronous operation
      • Discuss
    • 6. An RC circuit used in a 74122 retriggerable one-shot has an REXT of 100 kΩ and a CEXT of 0.005 µF. The pulse width is ________.

    • Options
    • A. 70 µs
    • B. 16 µs
    • C. 160 µs
    • D. 32 µs
      • Discuss
    • 7. In VHDL, how is each instance of a component addressed?

    • Options
    • A. A name followed by a colon and the name of the library primitive
    • B. A name followed by a semicolon and the component type
    • C. A name followed by the library being used
    • D. A name followed by the component library number
      • Discuss
    • 8. What is the hold condition of a flip-flop?

    • Options
    • A. both S and R inputs activated
    • B. no active S or R input
    • C. only S is active
    • D. only R is active
      • Discuss
    • 9. An RC circuit used in a nonretriggerable 74121 one-shot has an REXT of 49 kΩ and a CEXT of 0.2 µF. The pulse width (tW) is approximately ________.

    • Options
    • A. 6.9 µs
    • B. 6.9 ms
    • C. 69 ms
    • D. 690 ms
      • Discuss
    • 10. In a 555 timer, three 5 kΩ resistors provide a trigger level of ________.

    • Options
    • A. 1/4 VCC and a threshold level 1/2 VCC
    • B. 1/3 VCC and a threshold level 3/4 VCC
    • C. 1/3 VCC and a threshold level 2/3 VCC
    • D. 1/4 VCC and a threshold level 2/3 VCC
      • Discuss

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