4 to 1 Multiplexor Circuit Help

Discussion in 'The Projects Forum' started by katiestad, Jan 30, 2018.

  1. katiestad

    Thread Starter New Member

    Jan 30, 2018
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    This is my 4 to 1 Multiplexor circuit but I need help because it isn't right. Does anyone know what I'm doing wrong? It has to be in Simcir.
     
  2. dl324

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    Mar 30, 2015
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    Welcome to AAC!

    Is this homework?
     
  3. katiestad

    Thread Starter New Member

    Jan 30, 2018
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    No, it's not. I'm self-teaching about Computer Science through a book and I can't seem to figure out the MUX circuit in Simcir.
     
  4. crutschow

    Expert

    Mar 14, 2008
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    Please draw it as a normal schematic with right angle connections and a layout that minimizes the length of the connections.
    That drawing too convoluted to readily follow.
     
  5. WBahn

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    Mar 31, 2012
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    You might ask if your connections make sense, even from a symmetry standpoint. You S0 and So' signals each go to two of the channels. Wouldn't is seem reasonable for the same to be true for your S1 and S1' channels?

    Drawing the schematic in a neat, orderly fashion often reveals things like this because things just look unbalanced.
     
  6. dl324

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    The first thing you need to learn is that neatness counts. It makes the circuit easier for us to read and easier for you to troubleshoot connectivity problems.

    Look at the symmetry, or lack thereof, of the select signals.
     
  7. katiestad

    Thread Starter New Member

    Jan 30, 2018
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  8. katiestad

    Thread Starter New Member

    Jan 30, 2018
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    Is this easier to read? I'm not exactly sure the schematics of how to organize the circuit. Thanks to all for the help.
     
  9. WBahn

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    That's better, but see if that software lets you make straight lines and 90° bends in wires.

    Consider the following observations:

    Edit_2018-01-30_1.png
     
  10. katiestad

    Thread Starter New Member

    Jan 30, 2018
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    So I should make it symmetrical? I'm having trouble figuring out which switches connect to which gates.
     
  11. dl324

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    Not much better. One place to learn how the professionals do it is to look at datasheets.
     
  12. crutschow

    Expert

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    Yes.
    And make all the lines orthogonal, not slanted (also called rat's nest).
     
  13. WBahn

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    How did you come up with the connections that you have?

    Think about how you would describe the logic in words.

    You want the output signal to equal D0 if S0 is NOT pressed AND S1 is NOT pressed.

    You want the output signal to equal D2 if So is NOT pressed AND S1 is pressed.

    What would the corresponding statements be for D1 and D3?
     
  14. WBahn

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    As near as I can tell, this Simcir application only does rat's nest connectivity. So the best she can probably do is to position components so as to reduce the chaos as much as she can.
     
  15. Bordodynov

    Well-Known Member

    May 20, 2015
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    See
    2018-01-31_09-37-43.png
     
  16. dl324

    AAC Fanatic!

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    How is this relevant to what's wrong with the OP's circuit?
     
  17. dl324

    AAC Fanatic!

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    Simcir doesn't let you draw clean schematics. If you're self-teaching, why do you want to use it? There are better free logic simulators.
     
  18. Bordodynov

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    May 20, 2015
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    I showed that the electronic circuit must consist of inverters and 2-N-HE logic elements. It is also better to break the circuit into smaller blocks. Then it is more understandable. I also demonstrated the functioning.
     
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