The present invention provides a dimming circuit for controlling the luminance of a light source and the method for controlling luminance. An LLC power converter is cascaded with the PFC power converter. The yarn is untwisted by being twisted in a reverse direction opposite to the spin direction, andor further twisted in the reverse direction, to develop a high tensile strength and flexibility. The housing area is lined with a felt or cloth material to reduce noise caused by the treats striking one another or the housing area walls.