Abstract: A device for rain-induced switching on and off of an electric windshield wiper motor (10) in vehicles, is provided with a sensor (18) responding to moisture on the windshield and a control unit (16) for controlling an electric switch (11) for the switching on and off of the windshield wiper motor (10) as a function of the sensor signal. The control unit (17) is constructed in such a way that it detects the rate of variation of the sensor signal and only generates a switch-on signal when there is an increase in amplitude of the sensor signal above a predetermined amplitude magnitude in order to ensure the prompt switching off of the windshield wiper motor (10) when the rain ceases regardless of the formation of streaks on the windshield.

Abstract: A control circuit for an electric motor is proposed, whose rate of rotation and rotational direction depends on a control signal (Ue) at the input terminal (10). The rotational direction is given by means of a determined control signal level being exceeded or fallen short of. The rate of rotation is controlled by means of a pulse width modulation of the control signal (Ue). There is a nonlinear relationship between the change in the pulse duty factor of the pulse width modulation and the control signal. The mean adjusting speed of an actuating motor accordingly adapts to the control deviation signal of an actuating control.

Abstract: A ventilating arrangement, particularly an air conditioning arrangement, for a vehicle has an air passage extending from outside into a passenger cabin, and a flow regulating flap associated with the air passage and turnable by an adjusting motor, an impeller located in the air passage and driven by an electric motor with a variable rotary speed, and a pressure measuring element which is connected with the air passage upstream and downstream of a flow resistance arranged in the air passage and formed, for example, as a heat exchanger.

Abstract: The sawtooth voltage generator is intended in particular for use as a clock and reference voltage generator of an electronic regulating means for a motor vehicle heating system. The generator has an output voltage having a leading edge determined by a first RC circuit and a trailing edge determined by a further RC circuit. A first capacitor (C1) and a second capacitor (C3) are charged rapidly; the second capacitor (C3) has its own discharging circuit, e.g. a resistor (R7). The curve form of the trailing edge of the output voltage can be substantially freely determined with a nonlinear wave shape which is suitable for compensating for non-linear characteristics of elements of a regulating apparatus intended for receiving the output voltage with the operating frequency being determined by the discharge circuit (R4), the first capacitor (C1).

Abstract: A constant current source is provided for the energizing circuit of an electromotor driving a blower. The constant current source includes a battery connected in parallel with a series circuit including the energizing circuit of the motor, the emitter-collector circuit of a transistor and a control resistance. The transistor and control resistance are part of the constant current source. The base of the transistor is connected to the output of a differential amplifier the first input of which receives a reference voltage while the second input receives a voltage corresponding to the voltage across the control resistance and thus the energizing current. The reference voltage is derived from a potentiometer connected in parallel with the battery.

Abstract: To provide for essentially uniform tension of a safety belt extended by a user from a belt supply, a roll-up motor is mechanically, serially connected to a spring housing which includes a spiral spring, to which one end thereof is attached, the other end of the spring being attached to the shaft of the belt roll-up unit. A traveling nut is threaded on the shaft of the roll-up unit, axial movement of which is sensed by a three-position switch which controls the motor to pay out more, or take up some belt if the tension on the belt does not fall within the tension as set by the spring and controlling a center-OFF position of the three-position switch. Roll-up operation of the motor is started by a current pulse supplied from a latch switch incorporated in the engaging latch of the belt and abruptly changing state upon disengagement of the belt from the latch.

Abstract: A pair of relay contacts directly connect the electromotor to a battery when closed. One side of the relay coil controlling the contacts is connected to a battery when a thermostat responsive to engine temperature closes. The other side of the relay coil is connected to the battery through an electronic switch, in one embodiment a thyristor, in the other a transistor, which are in the conductive state when the ignition switch is closed. The thyristor further is conductive for one operation following opening of the ignition switch, while the transistor is conductive for a predetermined time period following opening of the ignition switch.