An apparatus is disclosed for automatic light dimming of electronic and
magnetic ballasts used for fluorescent or high intensity discharge lamps.
A variable capacitant's limiting current is added in the lamps which
provides lighting intensity controls without changing the ballast's
operation frequency. Several capacitors are placed in line with a
terminal for the lamp. The capacitor's switching capability is used to
change the current received by the lamp. The amount of voltage can be
controlled by either varying the supply voltage, or with an elimination
sensor, or by manual potentiometer control.