wien bridge oscillator with op-amp buffer

[fg45]

Hello,

I'm trying to understand a wien bridge oscillator circuit built using op amps. I've heard of a design that uses an op amp buffer on the output of the oscillator, does anyone know the reason for this buffer? is it to do with amplitude stabilisation?

many thanks

fg

 

[VEBill]

Amplitude stabilization in a Wein bridge oscillator is often accomplished using the non-linear resistance of a small ("grain of wheat") incandescent light bulb.

Using an active system to maintain amplitude stability can make it difficult to maintain the pure, distortion-free, sine wave that is the raison d'être of the Wein bridge oscillator in the first place.