Multisim question help

Discussion in 'Homework Help' started by ricky31290, May 26, 2016.

  1. ricky31290

    Thread Starter New Member

    May 26, 2016
    3
    0
    Hi All.

    Ive been given a question for my HNC assignment and to be honest im lost in what to do. So far ive duplicated the circuit pictured below but of course added in the values.

    Below is the question in quesion. Any help would be much appreciated.


    upload_2016-5-26_21-7-33.png
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,388
    497
    Ok.
    Lets see the list of values that you picked for:
    - which op amp are you using? 741?
    -R1
    -R2
    -Rf
     
  3. ricky31290

    Thread Starter New Member

    May 26, 2016
    3
    0
    R1 - 2
    R2 - 4
    Rf - 6

    Kept them small and even to try and make it easier for myself!
     
  4. ricky31290

    Thread Starter New Member

    May 26, 2016
    3
    0
    Sorry and yes 741
     
  5. MrAl

    Well-Known Member

    Jun 17, 2014
    2,425
    490
    Hi,

    You should really use resistor values that are in the k ohm range, like 1k, 2k, 5k, 10k. Small values like 1 ohm and 2 ohm dont work with most op amps because the current demand is too high.

    The whole idea behind the summer is that the two input currents must appear in the feedback resistor, being added together.
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,001
    3,229
    Arbitrary selection of parts values tends to lead to arbitrary results. :rolleyes:
    You have to know the limitations of the parts you are using and the 741 has many. Suggest you take a good look at its data sheet.
     
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