Electric power tool e.g. screw machine, has control circuit fitted to switch to gradually increase supply of electric power, by increasing ratio between duty cycle and off duration of switch

摘要

The tool has an electrical power source to power an electric motor (2), and terminals (6, 7) for connecting the power source to the electric motor. An electric switch e.g. FET (5), is provided for switching on/switching off the electric motor, and a control circuit (8) including a microprocessor is in series with the switch. The control circuit is fitted to the switch to gradually increase supply of the electric power, by increasing the ratio between duty cycle and off duration of the switch.