Digital clocks

Discussion in 'General Electronics Chat' started by Deborah Stephenson, Apr 8, 2015.

  1. Deborah Stephenson

    Thread Starter New Member

    Apr 8, 2015
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    A student asked me how is a clock's rising or falling detected? I had never worried about this. I told him his question was beyond the purview of the class but would research. He hates rote memorization. I explained that in beginning ckts, they do not teach you how to make a resistor, capacitor, or inductor, only how to use them. But I too feel his question.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    What is a clock signal?

    A clock signal is simply a transition from one logic level to another, for example, from logic LOW to logic HIGH, or from logic HIGH to logic LOW.

    The introduction of a clock signal and time as a parameter is the essential difference between combinational circuits and sequential circuits.

    In a combinational circuit, any change in an input will always produce the same output.

    In a sequential circuit, a change in an input (i.e. the clock input) may result in a different output depending on the previous state of the circuit. Hence the function of the clock input is to move from one state to another. We present this pictorially in a state diagram.

    See Mealy Machine:

    http://en.wikipedia.org/wiki/Mealy_machine
     
  3. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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