Does this question make sense?

Discussion in 'Homework Help' started by Tera-Scale, Jan 24, 2011.

  1. Tera-Scale

    Thread Starter Active Member

    Jan 1, 2011
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    I am really furious about my lecturer as he gave us something that we didn't cover in class. After a lot of reading I am doubting if this task does sense at all. All I want to know if it's possible to work out all of them and if makes sense in the first place as when I tried to analyze them I found them quite straight forward and had noting to do with the rest of the assignment.

    thanks Brandon.
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,140
    1,790
    What is you major malfunction? Of course it makes sense and where is it written that everything in homework has to be covered in class. Your expectations are seriously out of whack for someone aspiring to be an engineer.

    Calm down, buckle down, and put on your thinking cap. If you can show us some work maybe we'll answer a question or two.
     
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  3. beenthere

    Retired Moderator

    Apr 20, 2004
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    It makes perfect sense. It should give you some appreciation of the concept of fan out in logic.
     
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  4. Tera-Scale

    Thread Starter Active Member

    Jan 1, 2011
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    Oki i will look into it better. There is nowhere written that everything should be covered in class but I prefer that at least the basics are explained well so i can go into something further at home. bdw I can assure you that I've done my homework well on the rest but sometimes when certain concepts aren't made clear its difficult to appreciate the fan out for example. In the question there are floating pins which really confuse me :s If anyone wants to have a look at the rest of my assignment it's attached although it needs some finishing touches.
    thanks

    brandon
     
    Last edited: Jan 24, 2011
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Beenthere nails it again.

    Knowing the limitations of logic will keep you out of sticky situations later. Example of such as ordering a few thousand circuit boards to find out your prototype was using a few ICs that were on the "high side" of normal. Ever wonder where those "soldering practice" boards come from? :D
     
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  6. Papabravo

    Expert

    Feb 24, 2006
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    All right I just might give you a hint or two:

    1. A TTL input is the emitter of a multi-emitter transistor. It will source current into a low output which is driving that input. A unit load in TTL will source approximately 1.6 mA
    2. A TTL output, also called a "totem-pole" output, will very happily sink 10 unit loads or 16 mA in the low state, but a "totem-pole" won't source current worth a tinker's damn. A couple of hundred micro-amps MAYBE.
    That is part of the reason that you almost NEVER see pull down resistors in a TTL design.
     
    Last edited: Jan 25, 2011
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  7. Tera-Scale

    Thread Starter Active Member

    Jan 1, 2011
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    tnx PapaBravo,
    you already made it more interesting to me. I wish it would be that way in class. Now I understand why I didn't appreciate the fan out before - it's because its not in our syllabus to go into the internal schematic of a gate unfortunately, I will look it up in these ebooks.

    thanks again papabravo ;)


    Brandon
     
  8. Tera-Scale

    Thread Starter Active Member

    Jan 1, 2011
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    Are you referring to the static discipline of the ICs?
     
  9. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I came accross a PDF that might interest you.

    Bertus
     
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  10. Tera-Scale

    Thread Starter Active Member

    Jan 1, 2011
    164
    5
    lovely... very nice of you thanks! ;)
     
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