The shape and size of the graph changes due to the shape of the teeth and the amplitude and the frequency of this graph changes due to speed of the teeth passing the pick up sensor windings .
This sensor utillises Faradays Law
Magnetic or Inductive type Speed or position Sensor :
Modern engines need to know which position the crankshaft is so they can fire the spark plug and spray the fuel from the injectors at the perfect time to keep the emissions low and provide good performance .
These sensor consist of a winding and as a teeth(magnet) approaches the winding it starts producing a negative voltage in the sensor windings , when directly next to it sensor (windings) because not many fields are crossing the winding it creates close to 0 volts in the sensor. As it starts to travel away from sensor windings it start producing a positive voltage in the sensor windings , and how many time this cycle repeats itself per second is none as the frequency. there is a gap placed on some wheels as a reference point to TDC for ECU. Its real easy to find out whether they are inductive/magnetic type sensor because they are the only type of sensor which creates a negative and a positive voltage signal or in other words it creates analouge signal.
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