Wiegand proximity sensors are intrinsically safe—their self-powered characteristics mean that they can function without external power sources. There is no mechanical contact between the source of the alternating magnetic field and the Wiegand wire assembly and no wear. These systems will function reliably for billions of cycles. The rugged sensors can operate over a range of temperatures and also are insensitive to electrical noise. Response is consistent over a frequency range of near-zero to more than 30 kHz. The sensors are available in package form, consisting of a 15-mm length of Wiegand wire surrounded by a copper coil, all contained in an SMD-mountable plastic support structure.