problem with op amp positive and negative feed back at a time?

[chaitanya2k6er]

hi!!
I got stuck up with the op amp circuit which has both the positive and negative feed backs? What is the use of using op amp with both feed backs at a time? How to analyze the circuit? Please suggest me the solution with the required formulas.
Thank u..

 

[(*steve*)]

Do you want to post a link to the schematic?

And why do you want the circuit explained (it may help us in formulating a suitable reply)?

 

[chaitanya2k6er]

i have attached the circuits related to this.
no specific reason, i want to implement the circuit for some application.

 

[Laplace]

The basic technique for analyzing an op-amp circuit is to calculate the voltage at the (-) input to the op-amp as a function of the output and/or input voltage. Then do the same for the (+) input. Set these two expressions equal to each other, V(-)=V(+), then crank the algebra to get the output voltage as a function of the input voltage. So if I did the algebra right, the answer is Vo = V1(R1R4+R2R4)/(R2R4-R1R3).

 

[chaitanya2k6er]

thank u..
but i have not understood what you have suggested. Could you please elaborate it.

 

[Laplace]

Just write the node equations at the op-amp inputs, then solve for the output voltage as a function of the input voltage. See attachment.