A method for controlling the regeneration cycles for an air dryer in a closed ride height control system for vehicles. To eliminate the ripple formed, each separate processing output stage corresponding to a respective ac voltage source phase which provides a 120 Hz ripple, is stacked, in a series connection, and due to their respective ripple phase shifts of 120\xb0 degrees, achieves ripple cancellation at the output. A piston displaceable in housing longitudinal direction, serves to eject the product from the reservoir through an outlet opening. This data is transmitted to other modules by a multi-receiver serial bus. , the luminance level of the video signal or by the genre information included in the inputted video signal or the OSD display information used when the liquid crystal apparatus performs OSD display.