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Help with Logic Circuit

madz2007

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Hey guys,

Before i post what i need help with, i'll leave my skype if anyone would be kind enough to help me 1 on 1 please do :)

Skype: Live:mahdi.rajabi_2

Im having some problems figuring how to make this logic circuit.

This is the problem:

https://gyazo.com/1e4e58b73e6ec4881f1b8f1c6682cf66

I think i've figured out the truth table, but maybe wrong.


Edit:

Hey, im a Computer Science Major from the UK. I had a friend refer me to this website where he said i could possibly get some help in regards of the problem above^.
I know very little about this subject and wasnt aware of the module till it was introduced to me yesterday.

I have worked out the truth table for this, but maybe wrong.
 
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diachi

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That looks like homework or some such ...
 

diachi

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There's nothing against it, but just don't expect people to give you the answers. :)

Maybe introduce yourself first too...

Also, while many of the members here are well versed in electronics, this isn't a primarily electronics related forum.
 

madz2007

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There's nothing against it, but just don't expect people to give you the answers. :)

Maybe introduce yourself first too...

Also, while many of the members here are well versed in electronics, this isn't a primarily electronics related forum.
I'll do that, sorry for being so rude coming onto here and demanding answers. People just forget thing when they are needy, I'll introduce myself and hope i could get some help soon since my deadline in within 12hours :(
 

Seoul_lasers

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I'll do that, sorry for being so rude coming onto here and demanding answers. People just forget thing when they are needy, I'll introduce myself and hope i could get some help soon since my deadline in within 12hours :(

I second Diachi's posted comment.
Please introduce yourself first before posting here. Basic etiquette and protocol.

Don't expect us to give you the answers.---> but we can point you in the right direction.
The journey is yours and yours alone. All we can do is light the way (with coherent light no doubt). :lasergun:

Logic gates are a pain in the ass to work with and deal with like what you are doing. That was what I had to do last year for my digital electronics course.

Doing exactly this kind of problem I used this website to help out.
It worked.

Logic NOT Gate Tutorial with Logic NOT Gate Truth Table

Best way to visualize this problem is by virtualizing the circuit here 2 links (try them out) :

Logic Circuit official web site

http://logisim.sourceforge.net/

Good luck, hope the links help you.
 
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Cyparagon

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If it weren't for that zero input requirement, this could be done with a single NOT.

I also thought it was funny they say only AND, OR, and NOT are allowed, since ALL gates can be constructed with NOT+AND (NAND).

I haven't done this sort of thing in a while, but I could do it with 4 gates. There's your hint.
 

Cyparagon

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Your "circuit" doesn't make any sense. At all. 74HC08 is a quad AND.

Why are you using 3 gates on 3 chips instead of 3 gates on 1 chip?
the first gate you're using has its 2 inputs tied to V+. This is pointless.
The second gate has one input connected to the input of another AND. This is floating.
The third gate does not have its output connected to anything.
WHERE ARE YOUR INPUTS?

The green LED is permanently across the voltage rails. It will be on all the time no matter what.
The red LED is on a AND output where one input is always high, and one is always floating. The red LED will either flicker, or remain off.

You get a zero. try again.
 

Rivem

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A friend has helped me put this Logic Circuit up, representing that Truth table.

Circuit: https://gyazo.com/d5ccfb606866dececf15991fce19e064

Kmap: https://gyazo.com/98f99ac78f052ea89c5d35239a312121

What is the equation for the table? Can someone help me get the formula
Second what Cyparagon said.

As far as finding equations goes: ALWAYS find the boolean expressions before synthesizing your circuit. Read about how to do so here: link

Edit: Just as a tip, you have your Karnaugh map for the green correct, but the red is incorrect. You should be able to make your circuit using at most three gates very evident in the expression for red. If you want to be clever, it can totally be done with less.
 
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