Wiegand wire

Wiegand wire

[′vē·gänt ‚wīr]
(electricity)
A work-hardened wire whose magnetic permeability is much greater near its surface than at its center.

Wiegand wire

An iron-alloy wire that has unique magnetic properties. Invented by John Wiegand in 1972 and used in sensor applications, the Wiegand wire's outer layer can be magnetized without affecting the inner core. When an external magnetic field is applied, the core switches polarity to that direction and emits a large pulse. As the field is intensified, a smaller pulse is emitted.

Magnetic Key Codes
Used in keycard door locks, the plastic keycards have two embedded rows of Wiegand wires in a specific polarity pattern that represents a 26-bit ID number. When run through a magnetic field strong enough to switch the polarities of the inner cores, pulses are generated. The pulses energize a coil that creates a signal detected by a sensor. Although Wiegand cards are not as predominant as they were in the past, the 26-bit ID format has been carried over to many access control systems. See access control.
References in periodicals archive ?
Wiegand found that when a specially prepared piece of ferromagnetic alloy (the Wiegand wire) is subject to a reversing external magnetic field, it will retain its magnetic polarity up to a certain point, then suddenly 'flip' to the opposite polarity.
"Wiegand wire" is produced through a process involving the annealing of a Vicalloy spool wire (an alloy of vanadium, iron, and cobalt), then simultaneously stretching and twisting the wire to form a strain-hardened outer layer on the wire, surrounding a soft inner core.
Several short lengths of Wiegand wire were embedded side-by-side in the plastic body of each card.
When the Wiegand effect is used for rotation counters, a short (15 mm) length of Wiegand wire is located next to a permanent magnet mounted on a rotating shaft.
Here, a set of Hall-effect sensors measure the angular position of the shaft-mounted magnet within each rotation, while the Wiegand wire powered rotation counter tracks the number of complete turns.
Wiegand Wire. Wiegand Wire technology was developed in the 1950s and is now manufactured by HID Corporation (formerly Sensor Engineering).
While it is the most expensive card technology available due to the complex manufacturing process, Wiegand Wire offers better security, making it appropriate for use at airports, government agencies, power stations, and hospitals.
Embedded in the bottom half of the card is a series of parallel Wiegand wires. The Wiegand wire is a specially treated ferromagnetic wire.
Use of the Wiegand wire has currently increased for permanent product identification because of its durability.
Since the encoding of the Wiegand wires in the card is tightly controlled by Sensor, which still holds the patent, two identical badges are never made.