Stop Watch help?

Discussion in 'Homework Help' started by jkeith, May 15, 2009.

  1. jkeith

    Thread Starter New Member

    May 15, 2009
    2
    0
    So, I'm supposed to design a stopwatch circuit. The lab is in three parts:

    1) Build a frequency divider circuit to perform a divide by 60 function using the LINE signal from the logic trainer as a source clock. The LINE frequency is tied to the AC power frequency of 60 hz. The outpout of your frequency divider will be 1 Hz. Use 74LS90 chips for this part.

    2) Build a two decade up counter capable of counting from 0 to 99. The clock input to the circuit should be the 1 Hz output from part 1. The counter should be able to be reset to 0 by a logic switch (from the trainer). The count should be able to be stopped and restartred by a second logic switch. The outpouts of the counter are to be dispalyed on two 7 segment digits on an LED board. Use 74LS190 chips for this part.

    3) Build a circuit capable of timing events from 1 to 99 seconds using the circuits from partrs 1 and 2 and additional gate circuitry. The timer is to be enabled to count by pushing and releasing a logic switch. Once enabled, the timer will start timing. The timer is to be disabled by pushing and releasing the logic switch again. The number on the display will be elapsed time in seconds. The counter should be able to be reset to 0 by a logic switch.

    So... that's what I gotta do. The problem is I haven't got a clue. Neither of the chips it tells me to use are in the text, and what is in the text is very vague and doesn't even closely resemble the data sheets I found at TI's website, so I'm stuck not knowing where to plug everything in.

    I'm taking other electronics courses, but this one is giving me fits. So, needless to say, I was thrilled to stumble upon this website today.

    Any help is greatly appreciated.

    Btw, I'm using multisim 2001 if that matters.
     
  2. jkeith

    Thread Starter New Member

    May 15, 2009
    2
    0
    Okay, so I think I have the first part figured out... and if i can get the virtual lab i'm using to refresh and show my saved circuit, i'll u/l a pic of it here.
     
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