Magneto resistors have a variable resistance which is dependent on the magnetic field strength. A magneto resistor can be used to measure magnetic field presence, strength, and direction. They are also known as magnetic dependent resistors (MDR). A magneto resistor is a subfamily of magnetic field sensors or magnetometers.
A magneto resistor is a resistor for which the electrical resistance changes when an external magnetic field is applied.
Magneto resistors make use of the magnetoresistance effect. This effect was first discovered in 1856 by William Thomson, also known as Lord Kelvin. The effect is noticed in ferromagnetic materials and is dependent on the magnetic field strength and the angle between the direction of electric current and the magnetic field. This effect is therefore known as anisotropic magnetoresistance (AMR). Other, more recently discovered magnetoresistance effects are the giant magnetoresistance effect (GMR), colossal magnetoresistance effect (CMR), and tunnel magnetoresistance effect (TMR). Because most conventional magneto resistors utilize the AMR effect, the other effects will not be discussed in this article.
Permalloy, an alloy consisting of 81% nickel (Ni) and 19% iron (Fe) has a high anisotropic magneto resistance as well as a low magnetostriction (change in size due to magnetic fields) and therefore is a favorite material for magneto resistors.
Magneto resistors are often constructed of long thin films of permalloy. To increase the sensitivity of a permalloy magneto resistor, shorting bars of aluminum or gold are placed on the thin permalloy films under an angle of 45 degrees. This forces the current to flow in a direction of 45 degrees relative to the length of the film. This is called a barber pole configuration.
A typical AMR magnetoresistive sensor is constructed of a combination of 4 permalloy thin film magneto resistors, connected in a Wheatstone measurement bridge. Applications of magneto resistors as magnetic field sensing devices include:
The following symbol is used for a magneto resistor. It is shown as a variable resistor which is dependent on magnetic flux, indicated by 'x'.
Magneto resistors kuwa na upinzani kutofautiana ambayo inategemea nguvu ya uwanja wa sumaku. Magneto resistor inaweza kutumika kupima uwepo wa uwanja wa sumaku, nguvu, na mwelekeo. Wao pia hujulikana kama magnetic tegemezi tegemezi (MDR). Magneto resistor ni subfamily ya sensorer uwanja wa sumaku au magnetometers. Magneto resistor ni resistor ambayo upinzani wa umeme hubadilika wakati uwanja wa sumaku wa nje unatumiwa. Magneto resistors kufanya matumizi ya athari magnetoresistance. Madhara hayo yalipatikana mwaka 1856 na William Thomson, ambaye pia anajulikana kama Lord Kelvin. Madhara ya magnetism ni muhimu kwa ajili ya vifaa vya chuma na ni kutegemea nguvu ya uwanja wa sumaku na pembe kati ya mwelekeo wa umeme na uwanja wa sumaku. Kwa hiyo athari hii inajulikana kama anisotropic magnetoresistance (AMR). Kwa mfano, kuna athari za magnetoresistance kama vile athari ya magnetoresistance kubwa (GMR), athari ya magnetoresistance kubwa (CMR), na athari ya magnetoresistance ya handaki. Kwa sababu magneto-resistors kawaida kutumia AMR athari, athari nyingine si kujadiliwa katika makala hii. Permaloy, alloy iliyoundwa na 81% nikeli (Ni) na 19% chuma (Fe), ina upinzani wa magneto wa anisotropic na magnetostriction ya chini (mabadiliko ya ukubwa kwa sababu ya uwanja wa sumaku), na kwa hivyo ni nyenzo inayopendwa kwa upinzani wa magneto. Magneto resistors ni mara nyingi kujengwa ya filamu ndefu nyembamba ya permalloy. Kwa kuongeza unyeti wa resistor ya magneto ya permalloy, bar za kufupisha za alumini au dhahabu huwekwa kwenye filamu nyembamba za permalloy chini ya pembe ya digrii 45. Hii inahamasisha mkondo wa umeme kutiririka katika mwelekeo wa digrii 45 ikilinganishwa na urefu wa filamu. Hii inaitwa muundo wa nguzo ya mpanda-mvi. Magneto-resistive sensorer ni aina ya sensorer ya AMR ambayo inajumuisha 4 permalloy thin-film magneto resistors, iliyounganishwa katika daraja la kipimo la Wheatstone. Maombi ya magneto resistors kama vifaa vya kugusa uwanja wa sumaku ni pamoja na: Alama ifuatayo hutumiwa kwa magneto resistor. Ni kuonyeshwa kama upinzani variable ambayo inategemea flux sumaku, iliyoonyeshwa na 'x'.