op amp calculations!

Community Projects
1

Hello,

Please consider the attachment below.

I can’t seem to calculate r1 and r2 using:

Vout=AK2(V2)-AK1(V1)

r1 and r2 are supposed to be 2.5K and 7.5K respectively or a combination of resistors giving that ratio.

Somehow it doesn’t work out for me! :cry:

Can someone once again please check my work as to see where I am going wrong!

Thanks !

2

AK1 is not the gain. It’s -1*Gain, thus you’ve got a sign error. That’s why I used a k instead of a G.

Vout = G1V1 + G2V2 = G2V2 + G1V1 = AK2V2 - AK1V1

3

haaaa! I see …

thanks for your help!