Electricity and Magnetism > Magnetic Materials > Magnetoresistance
DCS# 5G45.70

MAGNETORESISTIVE SENSOR



APPARATUS
mounted AMR sensor with connector box
202-20-B4
strong magnet
202-20-D
digital multimeter 214-01-B
camera 201


DESCRIPTION
An AMR bridge sensor from an old computer floppy drive is used to show magnetoresistance.  The sensor consists of a Wheatstone bridge whose resistors are thin permalloy films.  Switch on the power at the connector box to apply 1.5 V across the bridge.  In a magnetic field, the resistance of the films change and so the output voltage changes.

These are used as position detectors in computer drives and in read heads.



REFERENCES
http://archives.sensorsmag.com/articles/0399/0399_18/main.shtml
http://www.ssec.honeywell.com/magnetic/datasheets/an211.pdf