A power supply is plugged into an ordinary household electrical outlet and conditionally provides a high frequency current at a power receptacle operative to receive the power plug of an ordinary table lamp; which table lamp has a special fluorescent lamp screwed into its lamp socket. Provided the special fluorescent lamp is indeed screwed into the lamp socket, and provided the lamp'switch is in its ON position, the power supply does in fact supply high frequency current from its power receptacle; which high frequency current powers the special fluorescent lamp at a nominal power level, thereby to provide for high- efficacy luminous output. A storage battery contained within the power supply is kept fully charged by current derived from the power line voltage normally present at the electrical outlet and functions such as to cause high frequency current to be supplied from the output receptacle even if the power line voltage were to be disrupted. To prolong the duration over which the battery can power the fluorescent lamp to a useful light output level, the magnitude of the power provided to the lamp during power failure may be reduced compared with its nominal level.
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