Need help with wien-bridge oscillator

If the 2 RC networks are switched (parallel RC network in the feedback loop, and the series connected to the ground)...

How does this change the frequency of oscillation?

I don't think the frequency changes but since the parallel network has lower impedance than the series network, the gain has been changed and it may not oscillate or may not be sineusoidal.

Thats exactly what I calculated..

The gain changes from 2 to 1/2

I just wanted to make sure though..

Thanks

headbuttking2 said:

Thats exactly what I calculated..

The gain changes from 2 to 1/2

I just wanted to make sure though..

Thanks

Click to expand...

If you're talking about the gain required for oscillation...
The standard Wien bridge (R1=R2, C1=C2) requires a gain of 3 to sustain oscillation.
With the network swapped around, I get a required gain of 1.5.
The problem with putting the series network to GND is twofold:
1. Positive DC feedback through the parallel RC network will cause the circuit to lock up. If you add a series cap,
2. you still have no DC bias to GND on the noninverting input.

The standard circuit solves both these problems.