Abstract: The invention relates to a regulator circuit for controlling the power fed to an electric motor from a voltage source, wherein the regulator circuit comprises a semiconductor switching element connected in series to the electric motor and the voltage source for the purpose of controlling the power fed to the electric motor, a control circuit for controlling the semiconductor switching element, and a first operating element for operating the control circuit by means of an operating signal generated by the operating element and fed to the control circuit, wherein a microprocessor is incorporated in the control circuit. The microprocessor can be adapted to control numerous functions within the regulator circuit, in particular monitoring and safety functions. It is however also possible for the microprocessor to be adapted to control the power fed to the electric motor subject to the operating signal.

Abstract: The invention relates to a control circuit for controlling a DC voltage power supply, whereby the control circuit comprises a switching element connected in series to the motor and a bypass switch connected in parallel to the electromotor for braking the electromotor by means of bypassing, with the bypass switch being formed by a semiconductor and the control circuit comprising a control circuit for controlling the bypass switch and a detector connected to the control circuit for detecting the status of the switching element. Semiconductors are less sensitive to vibrations and dirt. They are furthermore so small that they can easily be mounted on the same carrier as the other components of the control circuit. The control circuit is preferably arranged for gradually increasing the conductivity of the bypass switch once the switching element is open. Mechanical shocks when the tool is switched off are prevented by means of the partial conductivity of the semiconductor switch.

Abstract: The invention relates to a control circuit for controlling the power supplied from a power source to an electromotor, whereby the control circuit comprises a semiconductor switching element connected in series to the electromotor and the power source for controlling the power supplied to the electromotor and operating means connected to the semiconductor switching element for controlling the semiconductor switching element, whereby the operating means are arranged for controlling the semiconductor switching element when the control range of the semiconductor switching element is exceeded for at least a moment in a fully conducting state. Because the current reaches this value for at least a moment, the switch no longer has to interrupt a relatively large current.

Abstract: The invention relates to a switch for controlling the power to be fed to an electric motor of an electrical hand tool, which comprises a power supply connection, a motor connection, a controllable semiconductor connected between the motor connection and the power supply connection, a control circuit for controlling the semiconductor, and a safety circuit, wherein the switch comprises a cumulation circuit which is adapted to repeatedly measure a quantity prevailing in the switch or in its vicinity, assign a count value to the measured value of the quantity, cumulate the count values and generate a signal when the cumulated count value reaches a predetermined value. As a result of these measures the prior history of a component is included in the assessment of whether a situation is occurring which threatens the quality of this component.