Op Amp Design #2: Solving Vo = 3*10^4(i2-i1)

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Discussion Overview

The discussion revolves around designing an operational amplifier (op amp) circuit to achieve the output voltage equation Vo = 3*10^4(i2-i1), where i2 and i1 are input current sources. The focus is on the theoretical and practical aspects of circuit design, including component labeling and configuration.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant is attempting to design a difference amplifier but notes having more unknowns than equations, leading to confusion about the circuit design.
  • Another participant suggests that the circuit could be simplified to use only two resistors, indicating that the labeling of components may be incorrect.
  • A participant acknowledges the need to correct the labeling of resistors but expresses ongoing difficulties with the equations, questioning the necessity of the two-resistor configuration.
  • There is a suggestion to eliminate certain resistors (R1 and R3) from the design, indicating a potential simplification of the circuit.
  • One participant expresses frustration with the readability of file formats and the implications for accessibility in the discussion.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the circuit design, with multiple competing views on the necessity of certain components and the overall approach to solving the problem.

Contextual Notes

There are unresolved issues regarding the labeling of components and the assumptions about the circuit configuration, which may affect the clarity of the equations being used.

gfd43tg
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Homework Statement


Design a circuit containing a single op amp that can perform the following operation: Vo = 3*10^4(i2-i1), where i2 and i1 are input current sources


Homework Equations





The Attempt at a Solution


Where I'm at right now, I am just using the equation for a difference amplifier gains, but I have more unknowns than equations, so I don't know what to do.
 

Attachments

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Hi Maylis. Could I suggest that you post images as unadorned jpeg (or png, etc) files, so those using basic tablets (and costly data plans) are still able to participate?
 
Alright, here is a .png
 

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Your diagram labeling does not agree with your equations.

Big hint: since the inputs are current you need a total of only 2 resistors.
 
Oh I see, I need to change the label of R2 and R3. Either way my problem persists. The equation should be correct now with that change, as well as making it R3*i2 in my second stop
 
Last edited:
Okay, I source transformed, corrected the labeling, and this is what I came up with.

Edit: my bad, I was saying that no current goes through R1 and R3, which can't be possible since there is a potential difference between Vn/Vp and the resistors. Now the equations are even messier. Where do you get the fact that I only need 2 resistors from? I am following the template for a difference amplifier as given in the textbook and I redrew as my original image, pre-source transform
 

Attachments

  • 5.7 attempt 2.jpg
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  • 5.7 attempt 3.jpg
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Last edited:
See if you can get it to work without R1 and R3.
 
NascentOxygen said:
See if you can get it to work without R1 and R3.

And RL.


And BTW the pdf file is a lot easier to read, for me anyway.

If the new tablets, iPads etc etc can't even read pdf files any more I am more po'd than ever that xp is disappearing ... we are dumbing-down at an ever-increasing rate ...
 

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