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Homework Help: Pseudo Random Sequence Generator

  1. Apr 28, 2012 #1
    1.How to set the initial state of the Pseudo Random Sequence Generator?

    2. I'm using 74LS74 D-flipflop.I'm unclear how to use clear and preset enable inputs to set the initial sequence.

    3. I tried doing the experiment by directly giving the 0001 sequence through respective D-flipflop's preset inputs.But, I came to know that preset enable inputs, without clock input can be used to give asynchronous input.But, I didn't get any clear idea about how to set any initial sequence for this.Please help me.....Please give some reference links.....I googled but no direct material is available....My problem lies in not knowing using the preset-enable and clear inputs of 74LS74....please tell how to do that...
  2. jcsd
  3. Apr 28, 2012 #2


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    Staff: Mentor

    According to the datasheet http://www.datasheetsite.com/extpdf.php?q=http%3A%2F%2Fwww.tranzistoare.ro%2Fdatasheets2%2F68%2F68908_1.pdf [Broken] the PRESET and CLEAR controls are active LOW. Momentarily set one or the other LOW to set Q to what you need. See the FUNCTION TABLE.
    Last edited by a moderator: May 5, 2017
  4. Apr 28, 2012 #3
    Thanks for reply.......
    I have seen that and it's working now.......
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