operational amplifiers amplification level

[Tracid]

i would have one more question.
i got a connection like this one. i need the formula to get the Au(amplification level) of the amplifier.
does it change something in formula if i change the input polarities?

and could you give me some links where similar connections are explained?

Thank you very much again!

 

[js]

...only few links:

http://en.wikipedia.org/wiki/Operational_amplifier

**broken link removed**

**broken link removed**

 

[nanang_00]

that circuit is a non-inverting amplifier, and the amplification formula,
A = (R1+R2)/R1

if you change the input polarity (inverting amplifier), the formula will be
A = Rf/Rin
but the circuit will be different.

 

[pfm_pfm]

let me see

 

[Tracid]

So theres nothing to calculate with voltages? thanks very much!

 

[Ashish.chip]

This is a non-inverting amplifier having a gain of
A=(1+R2/R1)
if u change the polarity then this becomes a Inverting amplifier with a gain of
A= -R2/R1 -ve sign indicates the phase difference of 180 degree between input and output.
Keep in mind that change polarity such as feedback ramains negative if u will give feedback on +ve terminal then it behaves as a comparartor.

 

[Tracid]

Ashish.chip : i hope you missed an ´R´ at your equation, because you wrote A= (1+R2/R1) and not (R1+R2)/R1. but thanks!

 

[Pld4me]

Ashish.chip is correct.

Non-inverting gain = (1+R2/R1)

Regards,

Pld4me

 

[mince]

Ashish.chip : i hope you missed an ´R´ at your equation, because you wrote A= (1+R2/R1) and not (R1+R2)/R1. but thanks!

He was right.

(R1 + R2)/R1 = 1+R2/R1

 

[Tracid]

excuse me! what a stupid statement from me...!