A plurality of data keys are associated with a plurality of type values; query frequencies of the data keys are known. The lamp ballast circuit includes a voltage detector for detecting the level of a first voltage corresponding to an input voltage, a controller including an oscillator for changing the oscillation frequency according to the level of the first voltage, and an output unit for changing the frequency of the output voltage in correspondence to the oscillation frequency. The trimming system includes first and second pick and separate mechanisms arranged to separate each of the sheets in the stack of sheets and first and second cutters arranged to cut each of the separated sheets after the have been separated by the first and second pick and separate mechanisms. The load cable assembly has a load connector head connected to an end of a load cable.