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Student ? ( Logic Gates)

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radiobarn

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There is a question, probably elementary but im new at this, ? Is Design, draw, and wire a 5 input NAND circuit using one 2 input OR gate, one 2 input NAND gate , and one 4 input NAND gate.

Ive been drawing this circuit for a couple hours and have no idea, I know a 5 input NAND gate will only go low if all inputs are high, but with the 2 input NAND in there going low with its inputs high, I cant solve how to build this circuit, please help. Thank you.
 
Do you know how to apply DeMorgan's Theorem?

What happens if you tie the two input pins of the Nand gate together?
 
As this looks like a homework question just giving you the answer will not teach you to understand. So here is a tip. Apply DeMorgan's Theorem to the 2 input OR gate. The result will be a 2 input AND gate for NEGATIVE logic. The solution I came up with results in a 6 input NAND gate but you could just tie 2 inputs together or tie one input high.

Les.
 
1)At first I tried to take the OR + NAND and make some thing to go ahead the 4-NAND. In 20 seconds I could not see it.
2)What do we have? 4 input NAND + 2 input NAND
>>To make a 6 input NAND we would need (the 4 input NAND) OR (the 2 input NAND).
 
Thanks for the replys, yes this is a lab question where we are supposed to draw a schematic and the build it out and test on a breadboard. I still cant seem to make anything that will act like a 5 input NAND from these components, Im not sure how the OR gate should have any relevance in the circuit, tying the legs together makes it irrelevant, tying the 2 legs of the 2 input NAND together makes an inverter, the closest thing I can come up is different combinations where all 5 inputs are high will result in a low output, but there will be other situations as well that give a low output.
 
A = B+C = (or gate)
by Demorgan, A' = (A+B)' = A'B' implies output is 0 when both A is 0 AND B is 0. (Duality)

Does this give you any ideas how you could combine the outputs of the two NAND gates????
 
Make a truth table for this circuit: It has four inputs, so only 16 states. What logic function is it equivalent to?

gat.gif
 
I see it now, thanks Mike. I get myself confused with active and unactive outputs, i build it that way a few times im sure and when I looked at it , i thought well that wont work. Thinking too hard. Thanks again
 
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