| 摘要 |
PROBLEM TO BE SOLVED: To prevent unnecessary discharge of charges stored in a battery in a battery-type power tool equipped with a controlling electric power supply circuit to form the power supply for the control circuit from an electric power supplied from the battery. SOLUTION: Between a battery pack BP and the controlling power supply circuit 50, a protecting circuit 30 to make an input voltage to the controlling power supply circuit 50 equal or lower than the first voltage is installed when the output voltage of the battery pack BP is higher than the first voltage, and the action of the protecting circuit 30 is made to be off when the output voltage of the battery pack BP becomes not more than the second voltage.
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