Hi all, I am doing a project on electronics about the Wien Bridge Oscillator. I learned about impedances and operational amplifiers and now I'm trying to understand the Wien Bridge circuit. I'm having some problems understanding it and I would be very happy to get some help. I still have not understood why oscillations occur in this circuit, what are the conditions for oscillations to occur, and how it works mathematically. I would be extremely thankful if anyone could instruct me or relate me to some good material about it. EDIT: to be more specific, I've been trying to understand the analysis here: http://en.wikipedia.org/wiki/Wien_bridge_oscillator If it gives some more specific reference... but I am totally willing to try other materials as well. Thanks a lot, Omri
Check out this informative Powerpoint presentation: http://jeremya.com/engr/engr332/WienBridge-Oscillator.ppt
Correct me if I'm wrong, but it looks like the ratio should be: [tex]\frac{V_O}{V_A} = \frac{Z_S + Z_P}{Z_P}[/tex] and the presentation says it's inverse. In addition, I don't really understand how the resistors R1 and R2 affect the system - am I supposed to multiply the right hand side of the equation above by [tex]1 + \frac{R_2}{R_1}[/tex] to get it right? The most significant question I have is, why does the circuit create sinusoidal voltage? I can get why oscillations will occur but I don't get why they should be sinusoidal. Thanks for you help :-)