A system having an alternating current driven LED unit, an AC voltage regulator, and a controller is provided. The amplitude-versus-frequency response of the digital filter rolls off through the carrier region, so that there is substantially no boost of the amplitudes of lower frequency components of the baseband symbol coding recovered by the in-phase synchrodyning circuitry, with respect to the amplitudes of higher frequency components of the baseband symbol coding such circuitry recovers. The punched article is fixed on the hole together with the support in such a manner that the hole is completely covered by the punched article and the expandable body comes to rest inside the hole. The small digital audio files are created using natural language gaps, and are generally small enough to ensure that a first small digital audio file can be downloaded and played without significant delay, while successive small digital audio files are downloaded to be played in the future. One control method attempts to keep specific energy substantially constant by keeping a ratio between load and production substantially constant.