Abstract: A device for sensing velocity variations in a conductive body 10 moving through a magnetic gap 12 between two discrete portions 13, 14 of a magnetic circuit 15. The magnetic circuit 15 generates a magnetic flux 16 in the gap 12 to induce eddy currents 17 in the body 10 moving through the gap. The device includes an eddy current sensor defining at least one further gap 24 through which the body 10 is also moved, and at least one sensor coil 18. A voltage is induced in the coil by variations in the induced eddy currents. The voltage is detectable; providing an indication of variations, that is to say accelerations or decelerations, in velocity by providing two discrete magnetic circuit portions, the size and weight of the device be reduced while enhancing the ability to sense eddy currents. The device may be used in a vehicle to sense vibration, acceleration, or other motion.