Abstract: A driver circuit for driving an electrical load includes an input terminal pole connecting the driver circuit to an AC voltage source, an output terminal pole connecting the driver circuit to the load, a rectifier circuit connected to the input terminal pole for converting an AC voltage into a pulsating DC voltage, and a control element connected to the rectifier circuit and to the output terminal pole. The control element has a switch and a controller, the controller switching the switch on and off by means of a pulse train signal, wherein an electrical output value of the driver circuit is adjustable by switching the switch. The controller is configured to vary at least one time-based value of the pulse train signal within one period of the pulsating DC voltage such that a driver current is adjusted at the output terminal pole having a defined waveform within the period.

Abstract: A drilling machine, in particular a core hole drilling machine, having a mount on which an electromagnet is provided for attachment to a metal part on which a drilling unit is supported in displaceable fashion, wherein the drilling unit has a housing that accommodates an electric motor for driving a tool, is provided. There is provided a controller having at least one switch for switching on and off the electric motor and the electromagnet. The controller includes an operating and supervisory panel that is supported on an end of the housing opposite the tool. The switch for switching on and off the electromagnet and for switching off the electric motor is designed so that in the activated condition of the electric motor any operation of the controller will first cause the electric motor to be switched off before the electromagnet can be switched off.

Abstract: A magnetic drilling stand is disclosed having a drilling unit (20), having an electromagnet (14) for fixing the magnetic drilling stand (10) on a component (12), having a voltage source which can be coupled to the electromagnet (14), and having a controller (28) for monitoring the holding force of the electromagnet (14), with the controller (28) having a device for monitoring the current level of the electromagnet (14), in order to identify a fault state or an adequate magnetic holding force, with a signal for an adequate magnetic holding force being produced only if, within a test phase, the current level of the electromagnet is below a respectively predetermined threshold value at at least two predetermined times after the start of the test phase.

Abstract: A driver circuit for driving an electrical load includes an input terminal pole connecting the driver circuit to an AC voltage source, an output terminal pole connecting the driver circuit to the load, a rectifier circuit connected to the input terminal pole for converting an AC voltage into a pulsating DC voltage, and a control element connected to the rectifier circuit and to the output terminal pole. The control element has a switch and a controller, the controller switching the switch on and off by means of a pulse train signal, wherein an electrical output value of the driver circuit is adjustable by switching the switch. The controller is configured to vary at least one time-based value of the pulse train signal within one period of the pulsating DC voltage such that a driver current is adjusted at the output terminal pole having a defined waveform within the period.

Abstract: A magnetic drilling stand is disclosed having a drilling unit (20), having an electromagnet (14) for fixing the magnetic drilling stand (10) on a component (12), having a voltage source which can be coupled to the electromagnet (14), and having a controller (28) for monitoring the holding force of the electromagnet (14), with the controller (28) having a device for monitoring the current level of the electromagnet (14), in order to identify a fault state or an adequate magnetic holding force, with a signal for an adequate magnetic holding force being produced only if, within a test phase, the current level of the electromagnet is below a respectively predetermined threshold value at at least two predetermined times after the start of the test phase.

Abstract: The invention discloses a power tool having a motor adapted to drive a tool, comprising at least one switching element, coupled with a controller, for actuation of the motor, the controller being configured so that the motor can be switched on for driving the tool only when the at least one switching element is activated several times in a predetermined way, or when at least two switching elements are activated simultaneously or in a predetermined way in succession, there being provided at least three operating modes, namely an inoperative mode, in which the motor is out of operation, a working mode in which the motor is driven for driving the tool, and an intermediate mode, in which the user is signaled that further activation of a switching element is needed for transferring the motor to its working mode.

Abstract: A drilling machine, in particular a core hole drilling machine, having a mount on which an electromagnet is provided for attachment to a metal part on which a drilling unit is supported in displaceable fashion, wherein the drilling unit has a housing that accommodates an electric motor for driving a tool, is provided. There is provided a controller having at least one switch for switching on and off the electric motor and the electromagnet. The controller includes an operating and supervisory panel that is supported on an end of the housing opposite the tool. The switch for switching on and off the electromagnet and for switching off the electric motor is designed so that in the activated condition of the electric motor any operation of the controller will first cause the electric motor to be switched off before the electromagnet can be switched off.

Abstract: A circuit for a series motor for a power tool is disclosed, wherein reliable switching is achieved by means of two electronic switches, without the use of a mechanically disconnecting switch. To this end, two electronic switches, preferably triacs, are preferably connected in series to each other, the voltage drop across the triacs being continuously monitored by a monitoring circuit. A check for faults can be carried out before switching on the power tool. Alternatively, a fusible cutout can be tripped by means of a protective switch connected in parallel thereto.

Abstract: A circuit for a series motor for a power tool is disclosed, wherein reliable switching is achieved by means of two electronic switches, without the use of a mechanically disconnecting switch. To this end, two electronic switches, preferably triacs, are preferably connected in series to each other, the voltage drop across the triacs being continuously monitored by a monitoring circuit. A check for faults can be carried out before switching on the power tool. Alternatively, a fusible cutout can be tripped by means of a protective switch connected in parallel thereto.

Abstract: A core drilling machine comprises a stand on which a carriage is guided which can be moved by means of a drive in a working direction along a guide, wherein on the carriage a drilling unit having a spindle driven by a motor is received for driving a drilling tool, the drive comprising a stepper motor.

Abstract: The invention discloses a power tool having a motor adapted to drive a tool, comprising at least one switching element, coupled with a controller, for actuation of the motor, the controller being configured so that the motor can be switched on for driving the tool only when the at least one switching element is activated several times in a predetermined way, or when at least two switching elements are activated simultaneously or in a predetermined way in succession, there being provided at least three operating modes, namely an inoperative mode, in which the motor is out of operation, a working mode in which the motor is driven for driving the tool, and an intermediate mode, in which the user is signaled that further activation of a switching element is needed for transferring the motor to its working mode.