Move point C to make the 4 bar (double crank) rotate. Point E (green) will perform a trajectory that will be nearly a circunference.
While point E (green) translates along the piece of the curve that is almost an arc of circunference, point H remains stopped in the center of the circunference, and therefore, the crank of the dyad remains stopped. Move point G to make a design with a different dyad.