EFFECT HALL SENSORS

Sensors are called all those members who transform one physical largeness in other of nature electrical worker. The microphone, as an example, is a sensor, because it transforms the sound in tensions electrical workers. And it the fotoresistenza is pure, whose sensibility depends on the light that invests it. Also the termistore, that is the resistance to temperature coefficient negative, belongs to this formation of elements, because its behavior is conditioned from the heat of the atmosphere in which it is found dipped. In short. the sensor replaces, in a sure way, our senses, from the which drift the name, in order to operate here with logical intelligence where it comes employed. Between the multiple electronic expressions of sensors, in good part known from the readers, ve n' famous one is one little, but not for these immeritevole of mention. Draft of the sensors of Hall, that is those component small, various Foggia, often similar to transistor, that they generate tensions electrical workers when they are speeds up to you from magnetic fields and that, just for this, they also come calls magnetic sensors to you.

EFFECT HALL

The type of sensor, of which we are occupying, works in virtue of an uncovered electromagnetic effect in the 1879 from scientist E.H. Hall who, since that famous time, yields, how much illustrating in figure 1.

MAGNET

Fig. 1 - Schematic interpretations of the Hall effect. In absence of magnetic fields (design up), the electron, that they cover a conductor, proceeds ordinately from the point A to the B point. But when a magnet it is approached the conductor, the electrons endure a shunting line and between i points C - D of the section interested from the magnetic field manifest one volatge electrical worker.

That is, when on the termi­nali of a conductor outline of figure 1 is applied to one tension V up (), this, if it is a continuous ten­sione, promotes a uniform electron flow from the point To towards the B point, without that, between two extreme points of a trasver­sale section of conductor (C - D) sussista some diffe­renza of upgrades them. The index of the voltmetro, infat­ti, remains firm on the zero centers them. If, instead, like indicated in the outline low of figure 1, a magnet is approached the conductor, the electron flow endures a shunting line from the rectilinear distance, with a sure hoard towards the point D and a thinning in the next zone to point C. and the result electrical worker more striking ten­sione is that one of the presence of one, between i points C - D, marked from the index of the voltmetro. Inverting the polarity of the magnet, also the cor­rispondente electron concentration and the de­viazione of the index of the instrument are inverted. With the result that point C is this time more negative of the point To and the index of voltmetro flette towards the positive values you. More symbolically the concept than tension of Hall is expressed through the outline brought back in figure 2, in which with It goes indicates the tension of feeding of the circuit, while with GND the earth line is marked (ground = earth).

Fig. 2 - Symbolic outline of a sensor to Hall effect, whose it marks them of escape is prelevabile from i points C - D.

In a generalized manner, therefore, the tension of manifest Hall when a magnetic field of H intensity is involved, cross-sectionally, a conductor covered from current and is noticeable between the extremities of the two perpendicular sections.