#1529 DN6851 Hall Effect Sensor

Episode 1529 Chip of the day
Alternating Fields

[oskimac]

very interesting and informative. also, i searched: Edwin Herbert Hall, discover the HALL effect in the year 1879. This effect consists of the appearance of an electric field transverse to a conductor on which an electric current circulates in the presence of a magnetic field. Hall's experiments showed that the charge carriers were negatively charged particles. This fact was of great relevance since electrons would not be discovered until more than ten years later.

[robinbrowne]

Hall effect sensors are very cool. They are often used as rotation sensors in hub-motors for electric bikes. I have played around with these motors quite a bit, but the Hall effect is another one of those black magic mysteries which only the Wizards of Silicon Valley understand.

[RonDogInTheHouse]

Nice chip of the day! See you're putting to good use the power supply rail PCB, Nice.

Did an online search, Hall effect is the deflection of electrons (holes) in an n-type (p-type) semiconductor with current flowing perpendicular to a magnetic field. The deflection of these charged carriers sets up a voltage, called the Hall voltage, whose polarity depends on the effective charge of the carrier.

[byronwatkins]

Edwin Hall discovered it in about 1880. It is very important in studying solids because it allows us to measure charge carrier concentration (and sign).

[Enigma]

I suppose the alternating aspect would be useful for a tachometer if you were to mount magnets with alternating poles along a disk connected to the rotating shaft. The alternating poles would provide distinct transitions.

[justin.campbell]

You should get some analog ones and make a current sensor with them using a split toroid. I am working on one now, using an aditional sense coil to cancel the field for higher current capability and to pick up higher frequencies. I think it would make a good video!

[olivierconet]

Very interesting. Thanks !
On the datasheet I haven't seen info about the timings (sensing delay, maximum frequency)
How fast can this be ? (I have 3 hall sensors in my brushless motor that can turn pretty fast. That makes a few kHz)

[frankowalker]

These are used a lot in video machines to measure the speed of the video drum. 👍

[bayareapianist]

I was wondering if this sensor would keep its on/off status after its power cut off. If it does like a charged cap, for how long would it keep it?

[barrybogart]

Ok, but what I want to know is how they are used to measure DC Amps in a clamp meter.

[vanhetgoor]

What is the use of a circuit that tells you that something changed without telling you what the situation was before it changed. I will give the answer later. The contents of my wallet changed, into what? Is it empty now or filled so fully not one single extra South African Rand will fit in. And why continuously giving the signal that in the past something changed and only changing that when the situation changes again. I would like to know, if the subject is magnetics: is there a field and in what way is the field pointed, three possibilities, there is no field, there is a south pole, or there is a north pole present.
This Hall sensor is totally useless! Only for a moment it tells the truth, that is to say, at the moment it flips, but shortly after that it becomes unreliable, because you do not know if the changed field is still there, the field could have died out and nobody is informing about this.

[bruceblosser]

could use a Hall Effect Transistor with a rotating set of magnets, to drive an inductor based buck device!