Components and circuit analytics

Discussion in 'Homework Help' started by rio7, Jan 1, 2015.

  1. rio7

    Thread Starter Member

    Jan 1, 2015
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    Good morning,

    I'm starting learning about eletronics and eletronics circuits just 1 month later, so I'm beginner in this area. Right now I'm studying one circuits which I found on internet. I tested it in NI Multisim, everything works fine, but I don't know what mean " random " component ? Why this component need in this circuits ? What they do in this circuit ? Why we need just 5 V ? Maybe it can be much better in 10 V or 15 V ?

    Sincerely, Rio.
     
  2. wmodavis

    Well-Known Member

    Oct 23, 2010
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    What random component? I see no random component on the schematic.
    You need to be clear and precise as to what you are asking so we can possibly provide help.
     
  3. rio7

    Thread Starter Member

    Jan 1, 2015
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    Sorry for that. I'm just started to studying and learning about it. In picture I have selected these NI Multisim components with number ( 1,2,3 and ect. ) - 74LS192D , 74LS48D and ect.
     
  4. crutschow

    Expert

    Mar 14, 2008
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    So where does "random" come into play?
     
  5. wmodavis

    Well-Known Member

    Oct 23, 2010
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    But what do you mean my random component? Do you mean that 1,2,3,etc are random? By whose designation are they random - yours or.....??
    I suggest you read and understand the manufacturers data sheet for components you want to understand what they do/how they work and that should help you figure out what a component does and therefore why they are needed.
     
  6. rio7

    Thread Starter Member

    Jan 1, 2015
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    Sorry for that, my languages, mistake. I have mistake to say " random " , I want just to know and figure what these compotents, in my picture ( 1,2,3 and ect. ), do in this schema ? Like, example, if I deleted ( 3 number in picture ) component " NOT " my display show and count from 100 until 0, but if I add " NOT " component it show from 10 to 0. So why it happened ? I know he is working like inverter.
     
  7. rio7

    Thread Starter Member

    Jan 1, 2015
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    Update: And how to fix this problem ? When I press S2 I have this hex display ( picture ) 11 and 99 numbers. I need max 10 and min 0 in both hex display. Where is the problem ?
     
  8. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    First, provide a link to the page you got that schematic.

    What are you attempting to do with that circuit?
     
  9. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    "Form follows function."
    Those parts are there to accomplish the function.

    Why this component need in this circuits ?
    Because it is needed. Since you don't know nor care about the function of the circuit, there is no point to explain what it does there.

    Why we need just 5 V ?
    Because manufacturer who made that part told us to use 5 volts.

    Maybe it can be much better in 10 V or 15 V ?
    Manufacturer said to use 5 volts. If you are so simple that you can not follow manufacturer specifications, then you will simply burn/destroy the parts. If you have a lot of money, that is not a problem, just keep buying the parts and keep destroying them, and accomplish nothing to very little. Normal people don't have a lot of money, normal people have budgets and goals that they are trying to accomplish, so they, the normal people, follow manufacturer's specifications on how to power and how to use the parts.

    1. AND gate(s): http://www.ti.com/lit/ds/symlink/sn54ls08.pdf
    2. NOT gate(s), inverter: http://www.ti.com/lit/ds/symlink/sn74ls04.pdf
    3. See 2.
    4. Ground. Generally refers to point of 0 volts. Also referred as reference. Why? Because voltages at other points in the circuit are compared to that point.
    5. BCD Counter: http://www.ee.washington.edu/stores/DataSheets/74ls/74ls192.pdf
    6. BCD to 7 Segment Decoder, lights up correct LEDs to display correct decimal value: https://www.physics.rutgers.edu/ugrad/327/sn74ls48rev5.pdf
     
    Last edited: Jan 1, 2015
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  10. rio7

    Thread Starter Member

    Jan 1, 2015
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    I think this is eletronics forum about circuit, who can ask about everything You want ( in eletronics area ). So I think I could ask Why these component needed ? I don't know, so I write in forum. If I would know I don't ask these question. It's simple.
    Thank You for answer and these url, but still.. I don't understand why.. ( 5, 6, 1 and 2 - component needed ? ) ? I never study eletronics and this is my first time in circuit and ect, so I think best studying method is doing same circuit and studying everything component, testing it and learning about it. It's more interesting.

    Update: Now I fix this circuit and now max and min is correct!
     
  11. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    I guess your not going to post the link of where you found the circuit ... and now that you get the results you want, there is no need for me to look at the original from the link and your recreation in your simulator to see if there are any errors.
     
  12. ScottWang

    Moderator

    Aug 23, 2012
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    The input of U11A and U12A need to in series with a 330 ohm resistor connecting to ground, although when they floating that we will treat them like the high level, but left them keeping floating is not a good idea.

    You can refer to this 74ls192 application circuit.
     
  13. rio7

    Thread Starter Member

    Jan 1, 2015
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    Sorry, but right now I can't find it. It was from this forum. The schema results is like this - One hex display show +1 , second -1 and goes to max and min. Do You need my NI Multisim files ?

    Any idea to fix this circuit ? So I need resistors ?
     
  14. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    Maybe "random" is what he gets or his input when pressing buttons in a certain way.

    rio7, what is your nationality, please?
     
  15. rio7

    Thread Starter Member

    Jan 1, 2015
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    Danish
     
  16. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    So you want to know what the six components do in your circuit? Why are they needed? You have read and understood the datasheets. But you still do not understand their function in the schematic. Am I correct?

    Let's look at number 6. It is a 74LS48. Which is a BCD to 7 segment converter. It takes the 4 bit output of the counter and determines which of the 7 segments on a display should be lit to represent that number. Without it, there'd be no decimal display.

    Note that I included what it did and what would happen if it were unavailable. Sometimes, that will involve the attached components, like the 7 segment display that won't show the correct (if any) data.

    Now, you should make an attempt at identifying the remaining components function within the schematic.
     
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  17. rio7

    Thread Starter Member

    Jan 1, 2015
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    Yes, You correct!
    Thank You for Your amazing answer! Right now I understand this compotent! And what he doing!!
    I have one more question: I read in book that about these component ( in picture - 1 ) is " AND ", example - ( A*B ). Second ( in picture - 3 ) is " NOT " and he convert numbers, but I don't understand why these elements is added in this area ( picture ) after 74LS192D and before 74LS48D ?
     
  18. WBahn

    Moderator

    Mar 31, 2012
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    You need to download and read the datasheets for the components you are using.

    Here is a link to the data sheet for the 74LS192, for instance:

    http://www.futurlec.com/74LS/74LS192.shtml

    Regarding the supply voltage, why do you think 10 V or 15 V would be better than 5 V?

    Note that the 74LS family has spec'ed voltage supply limits of 4.75 V to 5.25 V. Anything outside of that range and the component may not work and may even be destroyed.

    From the other responses it appears that you are talking about the components next to your added notations of 1-6, correct? They are not 'random' -- they are there by design to accomplish specific tasks.

    You are jumping into the middle of something when you need to start at the beginning. Your approach is like starting to learn about hydraulics by asking what all of the various parts of an F-15 Pitch-Roll Compensation Assembly are for and whether they are really needed and why we can't use 8000 psi hydraulics instead of 3000 psi?

    You need to start with basic digital logic gates and learn how they work and how to design arbitrary functions using them and then how slightly more complex circuits work such as multiplexers, encoders, decoders, and the like. Then things like 4-segment displays and how they work and how a decoder chip such as the 74LS47 and LSLS48 relates to them and what the difference is when you use which. Then you can proceed to flip flops and then to counters.

    The logic below the counters is what is called "glue logic" which, in this case, takes certain outputs from the counters and controls certain inputs to the counters in order to get them to behave in the desired way.

    That you are asking about the GND symbol is highly indicative that you are jumping in at the wrong point. You need to learn about basic schematics and circuits, even just stuff involving a few resistors, to learn about your simulator and common conventions. The GND symbol is used to indicate the connection to the global reference node, which is defined to be 0V.
     
  19. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    You have to answer to which pins are the inputs of the AND and NOT connected, respectively. Answer one at a time. Just for fun and no other reason, which pin is connected to the NOT gate? And the output of the NOT gate is connected to what pin? And what are these pins defined as? Knowing the purposes of the input and output and the function of the NOT gate, you should be able to answer that part of your question.

    A similar exercise for the AND gate should bring you to another brilliant conclusion!
     
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