robotron

i understood some stuff and thanks for that. i couldnt simulate it on TINA. i understood the sallen key filter and i tried on tina to see that with my own eyes, the thing that if you use single bias polarity to the opamp you will get half the output voltage. i tried but with two points polarity i got outcome about 5V, with two points symmetric polaity only 6.5 volts. whats going on??? btw YOU JUST TOTALLY SAVED MY ASS ON THE RIGHT TIME WITH IT!!! it was for a colleg paper we had to create board (pcb), then say one thing or two about the circuit. btw, what does the first opamp do? again thakns

Hello. Have you ever seen this kind of opamps? i dont even know what this circuit does, not even one of the two opamps... Where's the power input of the second? ANd in the first one, ewhats going on with connecting the power input with the opamps input??? If anyone has even a slight clue, please comment. For gods sake there is feedback in feedback, the second's fdeedback is connected in the first's feedback. What i know this curcuit does is amplify some certain frequencies, only that. Please help