AND OR gate help

Discussion in 'General Electronics Chat' started by ddickey, Mar 25, 2012.

  1. ddickey

    Thread Starter Member

    Sep 28, 2011
    55
    1
    I need to set up this circuit, BCD+AB+AC+AD. So what I think is I need 5 AND gates and 3 OR's. I set them up on my breadboard and I'm only getting 4 of the 8 on's.
    AB'C'D
    AB'CD
    ABC'D
    ABCD My question, is there a site that explains how to hook up gates proper on a board?
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,446
    3,362
    You must have done something wrong on your breadboard. Can you post a clear photograph?
     
  3. Potato Pudding

    Well-Known Member

    Jun 11, 2010
    684
    92
    5 AND gates?

    Look at it as A(B+C+D)+BCD

    BCD is two of 2 input AND gates or 1 gate with 3 inputs.

    (B+C+D) is two 2 input OR gates or 1 gate with 3 inputs.
    and 1 AND gate to bring back the A term.

    and 1 OR gate to bring

    A(B+C+D) + BCD

    I count 3 ANDs and 3 ORs or only 2 of each if using 3 input gates.

    That is an important reduction because it means one less IC in the circuit.
     
  4. ddickey

    Thread Starter Member

    Sep 28, 2011
    55
    1
    I like this reduction. I'll give it a go. Thanks.
     
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