Magnetic sensors are AC signal generating devices that are used to indicate the rotational speed of a wheel or shaft (RPM). Magnetic sensors are widely used because they are relatively inexpensive to manufacture and are very reliable in the harsh automotive environment. Typical automotive applications for magnetic sensors include RPM pickups, cam and crankshaft position sensors, and ABS wheel speed sensors. All of these sensors can indicate rotational speed, with no mechanical contact to cause a breakdown from wear and tear.