A decoder question

Discussion in 'General Electronics Chat' started by tt1234, Nov 26, 2008.

  1. tt1234

    Thread Starter New Member

    Nov 26, 2008
    1
    0
    Hi,

    I wonder is there a decoder avalible for the following function? If not what is the simplest way to build one?



    Input: 0 0 0 0 Output: 0 0 0.....................0
    Input: 0 0 0 1 Output: 1 0 0.....................0
    Input: 0 0 1 0 Output: 1 1 0.....................0
    Input: 0 0 1 1 Output: 1 1 1.....................0


    Input: 1 1 1 1 Output: 1 1 1.....................1


    Thanks for help!

    Regards,

    Tom
     
  2. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    No standard off the shelf logic chip would do that function. These days the simplest solution would be to program a microprocessor to perform this decoding, you would need to have enough I/O pins (20 in this case) but it would be a easily implemented.
     
  3. steveb

    Senior Member

    Jul 3, 2008
    2,433
    469
    A programmable logic device works well for this too. (Note, only 19 pins, 4-in and 15-out are needed)

    Also, a standard decoder (for example 74159) could be combined with some or-gates.

    Or, you can work out a solution with only gates.
     
    Last edited: Nov 26, 2008
  4. PRS

    Well-Known Member

    Aug 24, 2008
    989
    35
    You can make your own decoder using 16 four-input Nand gates and some inverters. If you have a TTL data book it will show you the 74154 design (four-input, 16-output) design, but you'd have to rewire it for your purpose. Good luck!
     
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