NOVELTY - Power source controlling device comprises a hydrogen/oxygen generator for generating hydrogen and oxygen using direct current power supply applied from a battery, a remote control for generating signal to control overall operation of hydrogen/oxygen generator, a controlling unit for outputting predetermined control signal received from remote control, a voltage comparator for outputting level signal by comparing difference between output voltage of generator, and an AND circuit for outputting level signal inputted from voltage comparator and control signal inputted from controlling unit.    USE - The device is useful for electrolysis of water (claimed).    ADVANTAGE - The device prevents malfunction.    DETAILED DESCRIPTION - Power source controlling device comprises a hydrogen/oxygen generator (12) for generating hydrogen and oxygen using direct current power supply applied from a battery (11), a remote control for generating signal to control the overall operation of hydrogen/oxygen generator, a controlling unit for outputting predetermined control signal received from the remote control, a voltage comparator (13) for outputting the level signal by comparing the difference between the output voltage of the generator, an AND circuit (15) for outputting the level signal inputted from the voltage comparator and the control signal inputted from the controlling unit, and a power source controller (14) for supplying direct-current power of the battery to the hydrogen/oxygen generator by pulse width modulation.    An INDEPENDENT CLAIM is also included for controlling power source, comprising (a) controlling the power source without outputting hydrogen/oxygen generator by the control signal of the power controller by close the power switch to output low level signal on an output stage of the AND circuit when the outputting voltage of the battery is lower than the output voltage of the generator by comparing the output voltage of the generator and output voltage of the battery, (b) controlling the control signal of the power controller without outputting the power into the hydrogen/oxygen generator by outputting the low level signal on the output stage of the AND circuit by receiving off from the hydrogen/oxygen generator, and (c) controlling power by outputting power into the hydrogen/oxygen generator by the control signal of the power controller by switching the power switch on and outputting high level signal of the AND circuit without receiving off signal from the remote control.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the power source controlling device (Drawing includes non-English language text).    Battery (11)    Hydrogen/oxygen generator (12)    Voltage comparator (13)    Power source controller (14)    AND circuit (15)