Help designing the circuit

Discussion in 'Homework Help' started by nenadilic84, Jul 22, 2010.

  1. nenadilic84

    Thread Starter Active Member

    Aug 7, 2009
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    Hi,
    can someone give me a direction in designing the circuit that is suppose have an operation drawn in the diagram.
    [​IMG][​IMG]

    [​IMG] It has one input and 4 outputs. When the input signal go high nothing happens at outputs, but when it goes low the first output is triggered and it stays high for the same period of time as the input signal was. Next on low of the output 1 the output 2 is triggered and so on. Thanks for your suggestions.

    Regards,
    Nenad
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    This looks so much like an assignment that I am going to move it.

    Hint:Use the input as a clock - look up Johnson counter.
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    I'm thinking four monostables, each triggered by the preceding unit.
     
  4. nenadilic84

    Thread Starter Active Member

    Aug 7, 2009
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  5. nenadilic84

    Thread Starter Active Member

    Aug 7, 2009
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  6. Georacer

    Moderator

    Nov 25, 2009
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    If input is arbitrary and user defined, then how the circuit will know in advance the t_{on} in order to calculate the t_{on}/4. Doesn't seem very feasible to me...
     
  7. ozjon69

    Member

    Jul 19, 2010
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    Well, a microprocessor is probably the only simple way to do it. (first cct)

    Somehow, the circuit has to remember the value Ton.
    I can't figure how to do that with discretes

    The second circuit is impossible!
     
    Last edited: Jul 23, 2010
  8. nenadilic84

    Thread Starter Active Member

    Aug 7, 2009
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    Can you please give any suggestion for the second design of the circuit.
    I think that some frequency divider will do, but how to trigger on the falling edge?
    Thank you
     
  9. Georacer

    Moderator

    Nov 25, 2009
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    What were the problems with your design with the Flip Flops? What results didn't satisfy you?
    Concerning the second circuit, understand that you ask of a circuit to calculate the one quarter of a time interval that isn't yet known. How do you expect that to happen? Or did you describe your problem poorly and what you really wanted is to give the input time interval first, let it finish, and then start the chain of pulses?
     
  10. retched

    AAC Fanatic!

    Dec 5, 2009
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    If you waited 1 cycle to get t_{on}, then used that to trigger the 1/4t pulses for each additional cycle, that would work.

    But, you will need a way to get t_{on}

    Is t_{on} a pre-defined time?
     
  11. nenadilic84

    Thread Starter Active Member

    Aug 7, 2009
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    Yes you are right. But I expect that the simple way is to use a microcontroller with analog input that is going to define a t_{on} and make the pins high in the desired order. Thank you for the help.
    i will post the solution here.
     
  12. retched

    AAC Fanatic!

    Dec 5, 2009
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    That is correct

    You could use an analog or digital input to get the frequency of the pulse, then divide by 4.

    Trigger the output of T/4 with the input rising edge of the next cycle.
     
  13. big5824

    New Member

    Jul 15, 2010
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    Looks just like a serial to parallel shift register to me, although youd need a clock signal that isnt displayed
     
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