I don't know how to start

Discussion in 'Homework Help' started by ][ Shocked ][, Jun 14, 2009.

  1. ][ Shocked ][

    Thread Starter Member

    Apr 13, 2009
    Hello eveybody,

    I have a design problem and it's taking a big part of my classwork mark

    I didn't understand the problem

    it's described as following

    You have three sources with internal resistors,, respectively. You would like to design a circuit to perform the following operation:


    • State which circuit can perform such operation.
    • Design the circuit that performs such operation.
    • Justify all your answers.


    I just want to understand what is going on

    and what does that integral mean

    big thanks for the one who would help me

    and I will try my best to solve this problem, inshAllah
  2. mik3

    Senior Member

    Feb 4, 2008
    To perform this function you have to use a summer amplifier (op amp) with a gain of 1000 followed by an integrator circuit.
  3. ][ Shocked ][

    Thread Starter Member

    Apr 13, 2009
    I'm getting the half of the idea now

    but the other one is still away from me

    the integral here, what's does it physically mean?

    my math is so bad

    and thx alot for helping ^^
  4. steinar96

    Active Member

    Apr 18, 2009
    An integrator opamp works "similarly" to an integral because it "integrates" the voltage such that, the longer an input signal is applied the more output it puts out. Even though the output signal is a constant.

    An integral isnt anything physical really. It's just a symbol that represents the summing of infinitelysmall amounts of something. In this case it just "implies" that your circuit should use an integrator since it works like a integral, integrating the input signal and outputing something that is some kind of a sum of voltage inputs over time.
    Last edited: Jun 14, 2009
  5. ][ Shocked ][

    Thread Starter Member

    Apr 13, 2009
    ok im getting it now

    but still one question

    should I work wit dc sources or with ac sources?
  6. hgmjr

    Retired Moderator

    Jan 28, 2005
    I would start with DC sources until you get a clear understanding of what is going on.

    Are you using simulation software in this investigation?

  7. mik3

    Senior Member

    Feb 4, 2008
    The problem does not specify so you can use both AC and DC.
    In practical applications a DC source will drive the integrator into saturation after some time thus you need to keep the capacitor discharged all the time with a transistor and let it work when needed. This happens with AC too due to noise in the op amp.
  8. ][ Shocked ][

    Thread Starter Member

    Apr 13, 2009

    it's my first course in EE

    and we don't have transistors

    and capacitors are there, but not with op amp

    and yes, I could use a simulation software

    my real problem is with that integral

    what does it mean?

    does it mean my output voltage is

    ( v1+v2+v3 ) * 10?

    sorry for asking so much and thx alot for helping guys ^^