Shake to start! A differential amplifier based wien bridge oscillator. Since this kind of oscillator requires an exact voltage gain of 3 and that cannot be recreated in reality due to thermal drift and imperfections of the transistor's characteristics some form of voltage dependant negative feedback must be applied. Usually for lowest distortion a simple light bulb might be used for its PTC but since EC doesn't account for the PTC i had to resolve in using LED's that activate at 2V and apply a similar feedback.
