Help me with a Adder circuit

Discussion in 'Homework Help' started by yasthicklee, Feb 27, 2010.

  1. yasthicklee

    Thread Starter New Member

    Feb 6, 2010
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    Hello friends,
    I am in need of a simple 2 4-bit adder in which the output shud be added with the input.
    That is, it shud be capable of storing the output and use the same for the next add operation.And I shud supply only 1 4-bit as input.....
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. yasthicklee

    Thread Starter New Member

    Feb 6, 2010
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    Yes friend,I too looked over there and I was failed.I could not find the same which i need....

    I need a Adder where I shud give only one input.......And it shud be added with the previous value of the adder.And it shud work only once after a clock pulse...
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    That is why I gave you the other pages too.
    You will need a register (memory) for the "old" value.
    That is connected to the second value input of the adder.

    Greetings,
    Bertus
     
  5. yasthicklee

    Thread Starter New Member

    Feb 6, 2010
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    Hello friend,I triend the adder circuit with the Shift register 74LS195N.But when i gave the clock pulse for the first time (3 as my input) it is working.But for the second clock pulse I could not get the 6 as output.But I am getting 1 and in third clock pulse I am getting 2 and then 0.

    Help with the circuit.....
     
  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    What are you using as an adder?
    Take a look at the 74283 as adder.
    The 74195 can be the resgister.

    Greetings,
    Bertus
     
  7. yasthicklee

    Thread Starter New Member

    Feb 6, 2010
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    Hello friend I have designed with the same you have listed and I am still facing the above said error in previous post..Pls help me to get rid off this
     
  8. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    You have turned the bits around on the adder.
    Bit 1 => A (value 1)
    Bit 2 => B (value 2)
    Bit 3 => C (value 4)
    Bit 4 => D (value 8)

    Greetings,
    Bertus
     
  9. yasthicklee

    Thread Starter New Member

    Feb 6, 2010
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    But friend when I worked the same on the Multisim I got the output as 3 correct for the first time of the clock pulse........
     
  10. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    What did you do with the carry in connection?
    I would connect that to logic 0.

    Greetings,
    Bertus
     
  11. yasthicklee

    Thread Starter New Member

    Feb 6, 2010
    7
    0
    But friend,even doing all the things i could not get the exact circuit functioning in the right way.....pls help to sort out off this simple circuit.
     
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