counter and flip-flop question?

Discussion in 'General Electronics Chat' started by peaceofjake, Jan 10, 2005.

  1. peaceofjake

    Thread Starter New Member

    Jan 10, 2005
    The flip flop used in counters are edge-triggered types. this statement is
    a. always true
    b. false
    c. very situational
    d. generally true
  2. SiegeX


    Jul 22, 2004
    Consider this, if it didnt trigger on edges, then the only other thing it could trigger on are levels. By definition a Latch is a level sensitive device, and a Flip-Flop is an edge-sensative device. That should give you the answer right there.

    In case you didn't know that, you could reason it out by knowing that counters are counting discrete moments in time. If it were built on level-sensative devices, it would be continuous. Hence edge-sensative is the logical answer.

    A little tip on answering multiple-choice questions. The fact that options C and D are pretty much the same thing, or are at least objective, you can pretty much rule them out as the right answer. Leaving A or B, which is always or never which are definetely mutually exclusive.
  3. pebe

    AAC Fanatic!

    Oct 11, 2004
    I answered this same question on another forum and said that the statement is usually true - but not always.

    I can think of a 555 timer which uses a flip-flop controlled by the levels on its 'trigger' and threshold' pins. Another is an op-amp used as a level detector. The circuit usually provides positive feedback to give hysteresis to ensure clean switching of the output - so it's a flip-flop.