Simple Boolean Expression to Circuit

Discussion in 'Homework Help' started by goodbyegti, Apr 28, 2004.

  1. goodbyegti

    Thread Starter Well-Known Member

    Apr 28, 2004
    Hi peoples, just thought i'd comment on how great this site is before i start with my question, have had a good read of the boolean algebra section which has been very useful so far, as does the rest of the site. Anyway heres my question:

    I've designed a circuit and simplified it using a Karnaugh map and come up with the following after simplifying the minterms:

    R = A B C + A B C + A B C + A B C

    which i have simplified to:

    R = CB + CA

    which i hope is correct

    (btw sorry for underlines, they should be over the letters.. but i can't figure out how to do it on here)

    I now need to design a circuit for this expression using only NAND and NOT gates. I've ages messing around with designs and testing them manually against a truth table and I can't come up with anything that works. To put it simply does anyone have an idea of how i could build this circuit using NAND and NOT gates only? Thanks in advance...
  2. haditya

    Senior Member

    Jan 19, 2004
    i cant comment on the your simplification of the expression... i am too sleepy to work it out at the lets assume it to be correct.
    for your knowledge any gate can be built using a NAND or NOR gate.. these gates are hence called universal building blocks....
    so any logic circuit can be built using them.
    you will need:- 1 NAND gate to make a NOT gate
    2 NAND gates to make a AND gate
    3 NAND gates to make a OR gate.
    4 to make a NOR gate.
    4 to make a EX-OR gate
    5 to make a EX-NOR gate.

    with these clues try and work the problem youself...
    if you still need help msg back.
  3. goodbyegti

    Thread Starter Well-Known Member

    Apr 28, 2004
    thats very useful, thanks a lot, i've got a good idea of what to do now so i'll either figure it out and post up what i think to be the answer or i'll be back asking for more help! thanks again..
  4. goodbyegti

    Thread Starter Well-Known Member

    Apr 28, 2004
    Yep, sorted it, thanks for your help, I built a NOR, OR and AND gate from NAND gates like you said and then just used these to build the expression up..thanks again..
  5. m4yh3m

    AAC Fanatic!

    Apr 28, 2004