Abstract: Methods and apparatus for detecting particular frequencies of vibration utilize a magnetically-tunable beam element having a stress-sensitive coating and means for providing magnetic force to controllably deflect the beam element thereby changing its stiffness and its resonance frequency. It is then determined from the response of the magnetically-tunable beam element to the vibration to which the beam is exposed whether or not a particular frequency or frequencies of vibration are detected.

Abstract: A tilt sensor utilizes the “Wiegand Effect” to sense the occurrence of a tilting of the sensor from one inclined position to a horizontal position to another inclined position. The tilt sensor includes within a plastic or other non-magnetic body a non-magnetic elongated tube, a magnet that is contained and substantially freely slidable within the elongated tube, and a Wiegand wire that extends along and that is adjacent to the elongated tube. The tilt sensor also generally includes a coil wound on the Wiegand wire and a pole piece that extends along and that is adjacent to the elongated tube through which the Wiegand wire extends, and the pole piece is made of a material through which a magnetic flux path can be created. In operation, as the tilt sensor is moved from one inclined position to another inclined position, the magnet within the elongated tube slides from one end of the tube to the other.