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

[gfd43tg]

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.

 

[NascentOxygen]

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?

 

[gfd43tg]

Alright, here is a .png

 

[rude man]

Your diagram labeling does not agree with your equations.

Big hint: since the inputs are current you need a total of only 2 resistors.

 

[gfd43tg]

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

 

[gfd43tg]

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

 

[NascentOxygen]

See if you can get it to work without R1 and R3.

 

[rude man]

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 ... :grumpy: