Rangkaian Pembangkit/osilator gelombang sinus will produce a series of sinusoidal waves with the frequency 1:59 kHz. But if you have tried this series and measure the results with osiloskop or frekuesi counter, the resonance frequency is 1.65 kHz. This is known because of the distortion in a series of sliding phasa the non-linier.
Compensation for the distortion, and can be used a series of nonlinear feedback. For example, replacing the resistor with a dc RG 6volt 1 watt, the large resistor RF should also be adjusted to more or less fixed value 2Rg. Large flow through the lamp will not light it, but enough to warm its filamen. Large resistansi lights change according to the heat because of the flow through it. This makes the op-amp is not a liner. In the series of the Wien bridge sine signal a more professional compensation is usually made by adding a set of AGC (automatic gain controller)