A tachometer for supplying a signal representative of the rotational rate of a rotatable device includes a plurality of detection magnets, an index feature, and one or more non-rotationally mounted magnetic circuits. The detection magnets are coupled to, and spaced around, the device, to thereby rotate with the device when the device is rotated. The index feature is associated with the rotatable device, to thereby rotate with the device when the device is rotated. The index feature and the plurality of detection magnets are spaced evenly around the device. The magnetic circuits are spaced evenly around the device, and each magnetic circuit is configured to supply a first electrical signal each time one of the detection magnets rotates past the magnetic circuit and a second electrical signal each time the index feature rotates.