# Carno table problem

Discussion in 'General Electronics Chat' started by emicho, Dec 7, 2012.

1. ### emicho Thread Starter New Member

Apr 9, 2012
5
0
Hello guys,
I need to design a digital circuit which have five inputs " A,B,C,D,E"
and one output..
the output should be "1" when the input is a prime number
please I need you to helps me to find the reduced equation of the output
"using Carno table"...

Last edited: Dec 7, 2012
2. ### John P AAC Fanatic!

Oct 14, 2008
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Of course you checked to see what English-language answers come up when you look online for <carno table>. Knowing what your readers here would be likely to do.

You did, right?

3. ### emicho Thread Starter New Member

Apr 9, 2012
5
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well yes, but why are you asking??

4. ### spinnaker AAC Fanatic!

Oct 29, 2009
5,062
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I'm lost. Is the OP spamming?

5. ### emicho Thread Starter New Member

Apr 9, 2012
5
0
Hey!!!
I think I miss understand what you have said
I really have a problem with carno table which is the map method which we use to simplify a boolean function...
please I need help with my problem

6. ### John P AAC Fanatic!

Oct 14, 2008
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Oh, you mean a CARNAUGH table. Why not just say so?

Now explain what your inputs actually do.

7. ### Papabravo Expert

Feb 24, 2006
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You're all wrong. It is spelled with a 'K', not a 'C'

http://en.wikipedia.org/wiki/Karnaugh_map

For 5 inputs it will be hard to see the patterns across 2 tables. There are more effective algorithmic methods.

8. ### John P AAC Fanatic!

Oct 14, 2008
1,636
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Oops. Well, my spelling is close enough to get you to the right place. However, I was able to get there and not notice that I had it wrong. Not too observant, sorry.

Anyway, how does this relate to prime numbers?

9. ### tshuck Well-Known Member

Oct 18, 2012
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675
Karnaugh maps begin to get difficult to use past 4 variables, but 5 is certainly doable.. Have a look here before you begin...

Now, once that is out of the way, draw your K-map and put a 1 wherever the output should be a 1, corresponding to your input variables... So, you will eventually come to a Boolean expression for determining prime numbers....

10. ### emicho Thread Starter New Member

Apr 9, 2012
5
0
Thanks Guys, I have some PDF about it but the problem: I don't have time to read all this and I need your help to get the reduced equation of the output
"using Carno table" so that I can draw the digital circuit and I shout finish it today,

Thanks for all of you friends...

11. ### Papabravo Expert

Feb 24, 2006
10,338
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Sorry. We were not put here to do your work for you. You absolutely must make an effort. We are here to help, but you need to do the work. Understand?

12. ### tshuck Well-Known Member

Oct 18, 2012
3,531
675
I'm afraid that if you don't have time to understand your problem, you don't have time to come to a solution.....

13. ### vpoko Member

Jan 5, 2012
258
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You can use Mathematica or Wolfram Alpha to reduce boolean functions to a minimal form. Of course, if you have to use Karnaugh maps and show your work, you'll be out of luck.

14. ### spinnaker AAC Fanatic!

Oct 29, 2009
5,062
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Sounds like someone's homework is due soon.

15. ### WBahn Moderator

Mar 31, 2012
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As pointed out by others, an attitude like this will not get you very far here. But, more important, it will not get you far in your goal of learning anything (if, in fact, that actually is one of your goals) and it will not serve you well as an engineer. So if this is going to be the way you operate, get the hell out of engineering, both for your own sake and the sake of the people you will otherwise almost certainly get killed sooner or later.

Now, should you be interested in getting your act together, consider the following questions on this problem:

Q1) How do the lettered inputs, A, B, C, D, and E, map to a number (which is then either prime or not)?

Q2) How many possible input combinations are there that need to be dealt with?

Q3) How many combinations need to produce a '1' output?

Q4) Are any of the inputs always (or nearly always) in a particular state when the output is '1'?

Q5) Might it be easier to identify the cases for which the output should be '0'?

16. ### ErnieM AAC Fanatic!

Apr 24, 2011
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While this attitude may makes horrible engineer,it does strongly remind me of at least one engineering manager I've worked for.

17. ### MrChips Moderator

Oct 2, 2009
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Isn't that what managers are there for? They manage people but know bugger all about engineering.

18. ### WBahn Moderator

Mar 31, 2012
18,079
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Yeah, I was strongly tempted to make some recommendations of fields he might want to consider. But I managed, barely, to refrain myself.