So to give the sinewave the final touch, i use an integrator to generate a sine wave.

However, using only an integrator will make the output run away since the slightest offset will also get integrated over time.

The solution: a PID controller..... well ... just an I-Controller

The output follows the input and wont exceed this. By playing around with the integration factor (making R60 a potentiometer), i get this:

BEAUTIFUL !

Also as a comparison, without the preshaping:

You can see, the sinewave is slightly skewed to the left side..... NOT BEAUTIFUL