Abstract: A tire pressure detector for motor vehicles which is to be fastened to a wheel rim comprises a pressure switch actuated by the air pressure in the tire for monitoring the tire pressure. The pressure switch includes a reference pressure chamber with an electrically conductive switching diaphragm which closes the chamber toward the tire and which cooperates with a contact pin of the reference pressure chamber and an electric oscillating circuit connected to the latter in the detector housing. The reference pressure chamber (23) is axially clamped between a supporting ring and a spacing ring of insulating material in the metallic detector housing by a radial collar, which is formed, so that an annular gap is formed between the collar and the inner wall of the detector housing.

Abstract: A tire pressure detector for motor vehicles which is to be fastened at the circumference of a wheel rim and comprises an oscillating circuit having coupling coil which cooperates with a stationary receiver coil. In order to increase the minimum air gap between the rotating coupling coil and the stationary receiver coil, the coupling coil, which rotates with the wheel rim, is arranged on a middle limb of a plate-shaped ferrite core. The magnetic coupling for the stationary receiver coil is improved by means of the shape of the ferrite core (23).

Abstract: In a pressure sensor for detecting the air pressure in the interior of tubeless tires of motor vehicles, on a rim having two edge beads extending around its outside and a drum-like base, to facilitate mounting and provide malfunction-free, exact detection of pressure it is provided that the pressure sensor (10) is disposed in a bore (9) of the preferably radially inner section (5) of a bead (3), and in particular the longitudinal axis (43) of the pressure sensor (10) forms an acute angle with the axis (44) of the rim.

Abstract: A device for the transmission of measuring signals for the tire pressure of twin wheels of motor vehicles comprises for the purpose of enabling a simple exchange of the individual wheels in the twin wheel at least two signal transmitters which are arranged at each individual wheel in the area of the free outer rim edge in such a way that the first signal transmitter of the first wheel is electrically connected with a sensor of the first wheel and with the signal transmitter of the second wheel, and the signal transmitter of the first wheel is electrically connected with a sensor of the second wheel and with the second signal transmitter of the second wheel by means of coupling devices which are arranged on the rims. A stationary signal receiver is provided in the area of the free outer rim edge of the respective inner individual wheel at a distance from it.

Abstract: To calibrate a electronic compass provided with a magnetometer and being fixedly mounted in a motor vehicle the magnitude, and direction of interference magnetic field must be determined. For this purpose, a constant magnetic field Hg containing an earth's field component He' and the interference field component Hs, is measured by the magnetometer in a first position of the vehicle (Hg1) and then in a second position (Hg2) in which the vehicle is turned by 180.degree.. From the measured constant field magnitudes and directions, (Hg1, Hg2) the interference field component Hs is calculated according to vector equation H.sub.s +1/2 (Hg 1+Hg 2).

Abstract: In a process for establishing the driving direction of a vehicle by an electronic compass fixedly mounted in the vehicle and which is provided with a magnetometer having a computerized evaluation circuit the local curve (O) of the earth field (He) is determined from five measuring points (M1 . . . M5) which are established by turning the vehicle and corresponding signals are stored. The parameters for the center point displacement (Hs), the shape (ellipse) and the turning (angle .alpha.) of the local curve (O) in the vector diagram (x,y) are calculated by the computer by means of an algorithm with five unknowns for the five measuring points and thereafter the direction of the earth field (He) is computed. Subsequently, the vehicle is oriented to a predetermined cardinal direction and a correction angle is determined from the difference of angles between the cardinal and north directions and the earth's magnetic field direction measured by the compass.

Abstract: A magnetometer with a time coding is proposed, which serves to measure magnetic fields in the motor vehicle and in particular to measure the direction of the earth field and to determine the driving direction. The magnetometer includes at least one sensor having a horizontally disposed, magnetizable rod-shaped core and a winding disposed on the core. The winding carries an alternating current for generating an auxiliary alternating field, in order to magnetize the core in alternation up to and into saturation. In order to measure the magnetic field detected by the sensor and to generate the auxiliary alternating current, a controlled alternating current source (18) is connected on the one hand to one and the same winding (19), and on the other hand a measurement voltage that can be picked up at this winding (19) is connected to an evaluation circuit (21, 25, 12, 13).

Abstract: A process for correcting inclination dependent angle errors when establishing the driving direction of vehicles with an electronic compass for navigation is suggested. The compass comprises a magnetometer (10) with an evaluation circuit (11) for computing the driving direction. For compensating inclination dependent angle errors on the indicator of the drive direction the inclination angle of the earth field is fed into the evaluation circuit (11) as a calibration dimension (E), subsequently the inclination angle (.psi.) of the vehicle is established cyclically by means of an inclination measuring device (12) and then the corrected driving direction (.theta.) is established from the computed driving direction (.theta.') as well as from the calibration dimension (E) and the angle of inclination (.psi.) in accordance with the equation .theta.=f (.theta.',.psi.,E). This corrected driving direction can then be further processed or issued to an indicator (13) (FIG. 1).

Abstract: A magnetoresistive sensor used for emitting of electric signals in dependency on the position or the speed of a ferromagnetic body includes magnetoresistive measuring strips (10) on a substrate (12) which are exposed to a stationary magnetic field (H) such that a large field component (H.sub.y) extends perpendicular to the measuring strips and a substantially smaller field component (H.sub.x) in the plane of the measuring strips and at an angle of about 45.degree. to the direction of a measuring current flowing through the measuring strips. By approaching a ferromagnetic body (14) to the stationary field (H) additional field components (H.sub.z and H.sub.t) start acting on the measuring strips. The magnetic field component H.sub.t generated in the plane of the measuring strips changes in dependency on the position or speed of the ferromagnetic body and affects measuring current accordingly.

Abstract: The inductance of a variable inductor is put in series with a resistor to provide a delay circuit at the output of an amplifying path and the delayed voltage is fed-back to produce square waves having a period representative of the induct. The amplifying path includes a first amplifier and a final stage that includes a transistor. A second transistor is connected to a voltage supply line feeding the final stage and the delay network and is also connected to the final stage in such a way that the second transistor conducts when the first transistor of the final stage is blocked and so that the second transistor is automatically blocked when the output of the final stage is at a low potential. The base of the second transistor is connected through a resistance to a battery voltage line at a somewhat higher potential than that of the voltage supply line for the final stage.