How Does Pulsar Speedometer Work

  • Many modern pulsar speedometer are electronic. In the design derived from the earlier eddy current model, the rotation sensor installed in the transmission emits a series of electronic pulses whose frequency corresponds to the (average) rotation speed of the drive shaft and therefore to the speed of the wheels (assuming The wheels have full traction). The sensor is usually a set of one or more magnets mounted on the output shaft or (in the drive axle) differential crown wheel, or a toothed metal disc between the magnet and the magnetic field sensor. When the part involved rotates, the magnet or tooth passes under the sensor, generating a pulse in the sensor at a time because they affect the magnetic field strength to be measured. Or, especially in vehicles with multiple wiring, some manufacturers use pulses from ABS wheel sensors that communicate with the dashboard via the CAN bus.


    The computer converts the pulse into speed, and then displays the speed on an electronically controlled analog pointer or digital display. The vehicle control system also uses the pulse information for a variety of other purposes, such as triggering ABS or traction control, calculating average stroke speed or increasing The odometer replaces the odometer directly rotated by the odometer cable.

    Another early form of electronic speedometer relied on the interaction between a precision mechanism and a mechanical pulse wheel driven by the car's wheels or transmission. The agency will try to push the speedometer pointer to zero, while the electric pulsator will try to push it to infinity. The position of the lcd speedometer pointer reflects the relative size of the output of the two institutions.