SparkFun Forums

[8Volts]

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!

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

Thanks !

[Mee_n_Mac]

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 = G1*V1 + G2*V2 = G2*V2 + G1*V1 = AK2*V2 - AK1*V1

opamp10_9.jpg

[8Volts]

haaaa! I see ....

thanks for your help!