Hilti Aktiengesellschaft

Egon Konigbauer

Wolfgang Millauer

An electrical hand tool machine () having a motor switch () configured as a button and a current regulator () disposed in the current circuit of an electrical motor (), having a soft-start input (), in whose branch current a timing capacitor () is arranged. A current-direction-dependent element () is arranged between the soft-start input () and the capacitor ().

Electrical hand tool machine with soft-start

A circuit arrangement is disclosed for a non-contacting switch-over of operational parameters in an electrically driven tool, for instance, a hammer drill, which are determined by a voltage divider ratio with reference to a stabilized supply source. The voltage divider ratio is obtained by selective parallel switching of an additional ohmic resistor by means of a Hall switch, whose current supply is supplied by a Zener diode which lies in series with the stabilized supply source. The circuit of the Hall switch puts the low point of the additional resistor, connected through a diode, to the low point of the voltage divider, in parallel with the partial resistor of the voltage divider, through a drop resistance. The switching arrangement or circuit arrangement has the advantage that the current supply of an RPM control unit is only slightly additionally loaded or increased.

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Eichenau, Germany

Egon Konigbauer