An electronic ballast for high intensity discharge lamps is taught. A high speed electronic switch gates voltage across the lamp only for that period of time when the amount of resultant current flow will not adversely affect the lamp or the switch. At that point, the voltage is gated off for a period...http://www.google.fr/patents/US4904903?utm_source=gb-gplus-shareBrevet US4904903 - Ballast for high intensity discharge lamps
