2 Op-Amps & Resistors

[sarah90]

Hi i have 2 op amps inverting, they have 2 resistors each, 10k, 40k & 100k, 100k

how would I work out the voltage gain

is it 40/10 = 4, then 100/100 = 1 4x1? and does the answer turn negative?

 

[MrAl]

Hi,

Your gain calc sounds right. Since they are both inverting, the input voltage V turns into -V for the first stage, but then it inverts again so it's back to V.
Two inversion equals a non inversion

 

[sarah90]

**broken link removed**

thanks for you response, but its definitely not -4?

 

[audioguru]

**broken link removed**
thanks for you response, but its definitely not -4?

The first opamp is inverting and has a gain of -4 if its signal source has a very low resistance.
The second opamp is not inverting and has a gain of 2.
So the complete circuit has a gain of -8 (it inverts).

 

[sarah90]

Okay I understand it fully now, thank you!