Two spinning, oval-shapped oscilloscopes made from one hundred lines each. Get the cool effect by turning ‘Persist’ on.

Knob1 – line length
Knob2 – rate of rotation. left half controls counter clockwise rotation; right half controls clockwise.
Knob3 – offset of bottom oval
Knob4 – oval color & rate of change of color of top oval.
Knob5 – background color