Electronics 101: The Hall Effect explained
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- Опубліковано 1 січ 2025
- Hall effect devices are becoming increasingly common in the hobby. We have Hall effect sticks, compasses, and even hall effect sensors on gas motors which control the timing of the CDI ignition firing.
But what is the Hall effect and how does it work?
This video hopefully explains the way in which this effect works.
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The magnetic field, the current created by the voltage applied to the Hall affect device and the force acting on the electrons should be all orthogonal to each other. So on your white board the north pole of the magnet should be behind the white board and the south pole in front. Fleming's Left Hand Rule (for motors) gives these directions (it uses conventional current flow, even though that was subsequently shown to be the opposite to reality) would have the positive of the applied voltage at the bottom of the device illustrated with the negative on the top (if the negative of the Hall voltage is to appear on the right of the of a Hall affect device as illustrated).
So this entire 11 minute video is incorrect?
the magnetic field emanates from North. To get the deflection to the right as shown on his whiteboard, the N pole has to be in front and S pole behind the white board. F = q* v x B.
Took me a while to understand this comment, thank you for your explanation sir
Such an enthusiastic conductor. We love you for all the conducting you do.
I'd say semiconductor as his lecture affects my knowledge more than other conductors.
Wye bother? Does it relay matter?
This is an incredible explanation of a microelectronics concept that I've had difficulty grasping in the past. Thank you for taking the time to make it clear. Cheers!
I explained it in a much better and simpler way.
ua-cam.com/video/DtIz_HACSPI/v-deo.html
I've never seen the letter "S" written bottom to top. Great video: simple explanation of a complex subject.
This kind of teaching we need in our school system. I really believe when someone explain the things very well, he really understood the subject... I was trying to understand the principle of our turbine meter which has a pickup coil and a rotor. And I'm not sure how the pulses are generated. Now it's very clear to me and i know how to troubleshoot the equipment. Thanks sir.
You sir, are a wonderful teacher. I can tell that you love knowledge and that you enjoy sharing it with others. You've made this concept very easy for me to understand. Thank you so much, God bless!
Wouldn't the electrons be redirected in the direction into the whiteboard? Because F=q(E+v x B) where there is no external electric field, but the velocity is up, and the magnetic field is to the left, and the electric charge is negative. So by cross product I expect the applied force would point into the page.
Also, some ESC for brushless motors (most of the sensored ones) use Hall effect sensors as a feedback, to control timing.
Tiago de Pádua
Yes, I got one by taking apart an old computer fan to make a hot wire detector. Very useful.
Do you ever get a Hall effect when you walk along a corridor?
No... but I really a-door walking down corridors anyway. :-)
If there are three doors at the end of the corridor, you get the Monty Hall effect.
If there's a group of smokers you might see small Hall effect
Ok
If there is a hot babe at the end of the corridor, I get a Hall effect in my pants.
As a car mechanic this has helped me understand more how the sensors work in cars
Crankshaft / camshaft / distributors mostly use hall sensors. Thank you
Bangersnsmash Uk The mirror-mounted compass in many cars has one, too.
Nice quick video. I believe you have the direction of the magnet (magnetic field) mixed up. In the orientation you show the magnetic field is parallel with the movement of the electrons. The cross product between velocity and magnetic field would be zero. The magnetic field would have to be either into or out of the board.
Probably correct. Just a minute, I'll dig out my three dimensional white board.
Isn't the movement of electrons inside semiconductors perpendicular to the plane of board when magnetic field is parallel to the same plane?
Sorry but I've got to say this: always you get some one trying to boast how good they are ( electrons don't do that), COOL it you guys, Bruce was using the simplest explanations as to what hall effect is, so that everyone can understand. He's not doing a course in advanced electronics.
When trying to teach there is an obligation to get it correct. I'm sure Bruce once knew this stuff and 5 minutes spent revising would have resulted in a video that was substantially correct. This video is mostly incorrect.
mick sharp well said. I know nothing about electronics, this is WAY over my head, but Bruce has a real skill at explaining a subject that is mysterious to me. To all those who want to correct him...get your own channel.
Jim, AMEN to that!!!!
Jim Goodwin Well stated!
just curious what were some things that were incorrect?
Thanks for that video, this is certainly the best explanation I've seen so far.
Simplifying stuff is a skill , RESPECT.
It would be cool if you "electrically " took us from the radio transmitter we hold all the way through the prop spinning on an electric plane.... and everything in between. These are great and we learn so much!!!!! Thanks Bruce!
You are incredible at teaching and explaining, I love your sense of humor!
I explained it in a much better and simpler way.
ua-cam.com/video/DtIz_HACSPI/v-deo.html😊
i love these electrical theory videos Bruce! cheers!
It's not a theory...
I explained it in a much better and simpler way.
ua-cam.com/video/DtIz_HACSPI/v-deo.html
Fantastic video, I looked everywhere for good explanation and I couldn't find a better one! Thank you for uploading.
I thought electrons move according to RHR presence of magnetic field (assuming it has velocity)
You are correct. I was wondering if anyone else would bring that up. Electrons are NOT attracted by a magnetic field. They will experience the Lorentz force, however. Nice guy, but some of the stuff he says is cringe-worthy. :-)
The GMR effect (and its relatives) is often used for compass chips these days as its much more sensitive than the Hall effect (GMR effect is a quantum / spintronics phenomenon). For stronger magnetic fields sensors will indeed mainly be Hall effect. All conductors exhibit the Hall effect, but its a tiny small effect in metals which are very low resistivity. Being a semiconductor does not have the advantage you describe as holes and electrons cancel out partially - they both get pushed the same direction. The key point is you need a conductor with a very high resistivity (such as a lightly doped semiconductor). The sign of the Hall constant depends on whether electrons or holes dominate the current.
The field strength of a magnet drops off as the inverse cube of distance, not inverse square, this is because magnets are dipoles, not monopoles.
Actually they are pushed to the side by the magnet. Which side depends on the pole of the magnet that is closest to the sensor. For the shown deflection the magnet would have come from the direction of the pen on the board, not in the plane of the board. Apart from that a very good explanation.
Well, the electrons themselves are not much affected by the magnet. The moving charge is what gets pushed by a magnetic field. So you have to get electrons moving for them to be affected. That's one thing I noticed.
Hahaha, technically true, I guess that was one of the details he left out to simplify, which I understand as it is not crucial to understanding how hall effect sensors work. Good'ol right hand rule cross products.
One thing I think is most important in educational products: when statement is simplified, it cannot contradict scientific knowledge. "Electrons are attracted to magnet" is this general form is a false statement.
deelkar Really!?! All I can say is.... K.I.S.S. - Keep It Simple, Stupid! C’mon, man! Most of us just want to know how our gimbals control our planes or drones! We don’t want to read a two-inch thick book about the effects of magnetism on a semiconductor. We just want to keep our stuff in the air.
I don't like you saying that the electrons are attracted to the North pole as they're not really attracted to either. For the electrons to be attracted that way you'd have to have the north pole of the magnet behind the whiteboard (away from the camera) and the south pole in front of it (towards the camera).
You had me at “not *that* kind of conductor”.
Great video, all around!
Love your videos. Simple to understand. Gets me there quickly to get a GRASP on the subject. Looking at the thumbs down on a few and wondering why there are as many as there is. Then I realize they are the poindexters that go ( in a nasally voice) ," you said pie is 3.14. Nuh uh, your wrong it's 3.1415." We that watch your videos are laymen and don't have time to watch a 10hr video on the truest form of the subject and probably wouldn't even grasp it anyways. These videos are to get us in the ballpark on a subject and get the AHHHH I kinda understand now. Love your vids Bruce.
*Warning* : The explanation in this video is not correct. Electrons or any charge is never attracted or repelled by magnetic field. Magnetic field exerts force on, say +ve charge (q), by this formula F=q(VxB); So the force exerted by magnetic field causes the +/-charge to move perpendicular to the direction of motion and also to the magnetic field.
For proper explanation checkout this video ua-cam.com/video/xbGeMx0zOoc/v-deo.html
Actually the magnetic field falls off as 1/r^3 (not 1/r^2). Remember, there's no monopole term in the expansion of magnetic fields unlike electric fields
A channel where the comments are as educational as the videos. That’s for the correction!
Now this explained the hall effect its been since about 1964 since I studied electronics 🤤 I watched some other guy do an art lesson that left me more confused than when I started thank you for the simple well done explanation
So if a magnets south is positive, does that mean the Earths south is negatively charged? The amplification is the source voltage to the amplifier, so when the signal goes into the amplifier, it's come out as whatever the max voltage for the amplifier is... It would have to be the signal plus the supply voltage for the amplifier, the total voltage.
I was told the accent is learned by a very young child. Lip movements are recorded. Very good explanation.
Thanks for the great video. This is the best explanation I've see so far. Looking forward to more of these theory videos.
Great sense of humor and so interesting. Thank you sir
Hi Bruce if a engine used reluctor and hall effect sensor should the ecm have two setting reluctor and hall efect
I’m really struggling to find anything on Mr Hall on UA-cam.
Seems a bit like how Tesla wasn’t talked about when I was doing my Australian electrician trade school in the early 1990s.
Hello Bruce! Great video again, love the whiteboard!
Would love to watch a whiteboard video about optimization of power combo, from props to batteries, going through motors and ESC's, taking into account the weight or flying characteristics desired.
I know it's way too much for your small whiteboard and your almost finished markers, but you have managed yourself to explain so many things that I would think this is not a big task for you!
Thank you for your passion!
I explained it in a much better and simpler way.
ua-cam.com/video/DtIz_HACSPI/v-deo.html
I'm running stepper motors that run on pulses . Can a Closed loop hall effect current sensor be used to count pulse/steps of the motor ? And act like an Encoder?
I find dozens of wiring diagrams for connection to an ardino but none for connecting to a mach 3 BOB, is that they cannot act like a Normally Closed switch, or they just don’t work on my type system. I really need a wiring diagram for my system.
Thanks.
Love these types of videos. Thanks Bruce!
Is the word 'Hall', the scientist's name, like Volta and Ampere, who discovered it ? Or, is is referring to a sort of hall in the electrons/device or such ?
Hi Xapk here again..... just wondering if you know how Hall effect is used in a torque sensor. My e bike's conked out and suspect the torque sensor. Various wires going between the sensor and the controller 6 in total. Just wondering if there's an obvious function of them all which I could test out. One pair is likely to be just a simple DC current.
RCModelReviews.. So.. is it possible using it as a Switch? Almost like a Reed Switch?
Is there a way to tell which wire is which? I have a new wheel speed sensor to install, but the company changed it with no plug and told me to just splice the wires together. I think I know but I'd like to know for sure I'm wiring it right the first time.
Good side, is entertaining and sort of explains the Hall effect. Room for improvement: electrons are NOT attracted to the magnet (nor repelled by it), the experience a force perpendicular to their velocity and the magnetic field. In the video they would not arrange themselves on the sides but in the back of the whiteboard, leaving positive ions in the front (as they would do with semiconductors too).
Hello, please why we connect resistor between supply and output signal in hall effect circuit ?
how repeatable is the output? If I used a comparator and move a magnet near and away, with it trigger at the same distance each time? thank you.
Excellent explanation. Thank you so much. You’ve really made this very clear and are unique in your ability to make the complex understandable!
great vid and thank you Bruce.?why do we use pots if hall sensors are more efficient.?.are they more expensive to produce?.Ime into driving sims as well as rc planes.why do they use pots on the foot peddle apps and hall on my gear shifter?.sorry for my ignorance.
How can I make a speedometer out of the hall effect, please? What is the principle behind it?
Good explanation of a "mysterious" electronics term. I LOVE this sort of video. Many Thanks Bruce.
Can you tell how to calculate the spacing of 3 hall sensors in 3-phase motors with different winding schemes?
Why don't university teachers explain these as simply and clear as you?!
Would a drop of thin ca help that crack in your spectacle lens?just curious,thanks for what you do Bruce
jon mellor - I hope that didn’t happen from one of those dangerous drone pilots crashing a deadly craft into his head. O_o. On a serious note, I’ve never tried CA on lenses but depending on the material, glass, polycarbonate, etc., it could cause that nasty hazy effect.
Yes please, an explanation of how those solid state gyros work. Black magic I guess. Keep up the great work Bruce.
I disagree with his curved electron path. The electrons would curve to the side until they reached the edge of the conductor, but they would not curve back again.
The force the electron experiences is called the Lorentz Force, and the equation is F = V X B, known as the vector product, outer product, or cross product. The direction of the force uses a simple right hand rule. Point you fingers in the direction the POSITIVE charge is moving and curl them toward the direction of the magnetic field (out of north pole into south pole). Your thumb points in the direction of the force. Since electrons are negatively charged they experience a force in the opposite direction.
In his picture, the electrons are travelling upward and the magnetic field is pointing to the left, so point you fingers up and curl them to the left. Your thumb points out from the whiteboard. But electrons are negatively charged so the electrons would experience a force pushing them into the whiteboard or away from you.
That is nice video, and I did learn why this is used rather than a potmeter.
However, the explanation is very very very very simplified. In actuality, electrons aren't attracted or repelled my a magnetic field, but moving electrons experience a lorentz force while going through a magnetic field. The magnetic field would have to be perpendicular to the whiteboard in order for it to work (but it's kinda hard to draw).
Everyone seeing this will go, run think they understand it, write it as attracted in the report, their third year lecturer will see this, slap their face and bang their head on the table. Thinking... Did they learn anything at all. Remember, Physicists feel that physics is a crucible degree, its either for people or not. This explanation will make many think that it really isn't for the person who was just confused.
Mr. Bruce. Hi. I have a friend who is involved in mining Silicon. He has related to me that determining the quality of what is valuable to them is somewhat time consuming.
I am wondering if there is a way they could run a guick preliminary field test that might indicate whether the sample would be of interest for further evaluation.
Something like a quality magnet and voltmeter, in the pocket so to speak.
Thank You
Best Regards,
Susan
My main question is how fast is the hall effect monitor versus some other form of current sensing? Would it be considered a slow sense or a fast sense?
Walter Bunn Generally, slow. A quick Google search reveals that hall effect devices are good from D.C. up to somewhere in the mid-10's of kHz. For example, I saw high specs of 1, 25, and 80 kHz on different devices. HTH
You may have some things wrong if you reverse the polarity of the voltage source does the voltage at the meter reverse? if I'm been taught correctly it does, it would not be that the magnet attracts or repels electrons by the magnetic pole because it would all way attract electrons by one pole and repel by the other regardless of the perpendicular flow of electricity. The direction of the flux field, which reinforces or collided with the electromagnetic direction of the plate making one side the easier path and therefore causing one side to have more electrons, that is more likely responsible for the hall effect.
Some potentiometer use coils which will have stronger magnetic fields, that may be what is needed for your pot explanation.
We do not know if this has anything to do with hell, because hell may have different physical properties, maybe even a different dimension, be an alternate reality that exists in a parallel to our own, but where things work or happened differently, or something.
I know it's not really related to the Hall Effect, but I was wondering when and if you will be reviewing more DLGs. I'd like to hear your opinion on some begginer models like the Elf and the HK Raven.
Love your energy! Kept me interested in the Hall Effect an makes me wonder about if one could derive electricity from a field as weak as .5 Gauss?
Depends how much coils you have, look up faradays law for further research interesting stuff.
maybe if u jacked enough power into it, might increase the effect a bit, but bit of a waste of electricity unfortunately.
great one Bruce......I had a go at explaining hall and its benefits in one of my videos but not a patch on your explanation.....
Where are those 3D whiteboards when you need them?
I suppose will be commonplace enough any day now that AR and VR are becoming more developed and more widespread - especially given considerable 3D rendering prowess of smartphone/tablet processors.
You are the teacher ive been missing my whole life idk how kany videos ive randomly watched but you hleped me understand so easily ive been wondering lately what effect a magnet would have on current, thank you !!!!!! Is there any way i can get specific answers on certain questions not normally asked?
so which way does go BOTH depending on which side is depleted
You are the cool professor we never had.
but the induced electric field must be perpendicular to both applied mag field and current. according to this video it is parallel to applied electric field. how is this possible??
Love these types of vids... Always fun to learn how everything works.
I would hypothesize that the hall effect might not be measurable without using the semiconductor, much the same way you couldn't measure the pressure difference between the water at the surface of a pool and the bottom of the pool by using two hoses filled with water. Since gravity is creating the pressure difference, and the water in the hoses weighs the same as the water outside of the hoses, there will be no pressure difference created. Unless you fill the hoses with something other than water, which then you can measure the difference in pressures created by gravity's disproportionate pull on the heavier substance (the water). So I would suspect that that same hall effect that is pulling electrons towards one side of the conductor, would also equally pull electrons away from the conductor being used to measure that effect, unless the effect were disproportionately stronger in the material being used. Which it is apparently. So that's something interesting to take into account here.
wow. another great video. Very educationsl
Dumb question for you. What is best order to remove connectors from a battery source?
disconnect the negative side first as that is the side electrons are moving out
Will hall effect work in a room, or do you have to be in a hall?
+3 for the Aussie accent!! Love from Sacramento, California sir!!!!!!!!!!!!!!!!!!!
What is the difference versus inductive sensor?
Thanks bruce...helped me understand my hall effect distributor, on my truck
Do electrons flow or do they vibrate depending upon the potential?
Electrons of an electric current in metals, move in the 'Fermi Surface' not shells. Those in shells remain with the atoms of the metal.
Nice to know how Hall Effect works. I understand Mechanichal Gyros, how do the Electronic ones work?
Mostly by having a small bunch of accelerometers at a distance from one another. Although they're all on the same IC, the distance is ample for sufficiently sensitive accelerometers to calculate the difference. I think engineerguy did a video on MEMS accelerometers, that should help you further.
I kept the hall effect A3144 near a power supply transformer for months. I checked, it was all broken. The response to the magnet is wrong. Is there a connection? (sorry I use google translate)
How does one zero the reading? So that you get high low.
I'm very slow at grasping anything in the topics of physics but what I always tend to do to help me grasp it is to look at the foundation of most all things which is the table of elements I think we are on 118 of them, also I remember the fact that as humans we try to control things for ease of use so for instance if we have 600 volts power source and all we want to do is power a 60 watt light bulb we need to find a way to step down the power and obviously that's where all the components like capacitors and semiconductor come into the equation.
I explained it in a much better and simpler way.
ua-cam.com/video/DtIz_HACSPI/v-deo.html
I’m glad to see Whitey Bulger decided to make a career change .
Also, excellent explanation , thanks !
Electron Flow Model versus the Convention Current Model.
there is an experiment which is meant for calculating Hall coffecient, what is this hall coefficient.?
That was a bloody wonderful explanation, well done!
I take from this video that Hall effect gimbals are much more durable than the pot style yes? :)
Aren't sensors using GMR now instead of the hall effect?
To read earth magnetic field with high sensitivity? Probably. But i suspect there's no point going high-tech when low-tech works, and hall effect sensors have been around for a very, very long time and are dirt cheap now.
A Hall Effect device is used in the ignition distributor in some Ford cars in the nineties . Why...I suppose to read electric flow like timing
I love your disclaimers at the end of technical vids. I suppose they cut down on the geeky nit-picking a little but probably not enough.
;)
what is the 'conductor' ....... the rectangular component in the circuit ?
Your whiteboard videos are my favorite. Keep em coming Bruce! :)
??? how can we find the exact number of charge carrier in any materials as hall voltage is related with carrier density and mobility, so if hall voltage varries with magnetic field then carrier density for single material will be different ??
there must be electron flow flowing thru the hall sensor...if so it must be powered by a battery or an energy source...this is a question...
Home heating Condensing boiler with Hall Effect sensor in a EBM blower with speed issues how would I diagnose it? Could a ignition at 10,000 volt near a fan cause a sensor to loose the Hall effect.
Thank you
Learning the Hall Effect from a bloke in a flannel. Love it :)
Very interesting video, but I'm almost certain magnetic fields change in intensity by the inverse cube law not square.
How can you use the hall effect as a switch using the electrostatic energy from a finger for example? e.g. touch lamps
What if you turn a magnet into a pyramid and point it out from the battery will the energy travel up from the tip of the pyramid up towards the earths magnetic field ?
Learned something today! Thanks for the video!
The explanation was superb. Especially the bit with the op amp . . . you might include a Schmidt trigger in your next one.
I'm trying to imagine how this works in a component I have to repair. The Hall effect motor drives a shaft either in or out, (it's a linear actuator). But how does this particular motor reverse the polarity to send the shaft in extend or retract position?
Thanks Bruce ...ah the whiteboard , reminds me of my physics lessons run by an ex army colonel.
He used to push Mercury around his desk with a pencil , to demonstrate its properties at room temp!
I used to do that as a child back in the 1940/50s :) No-one bothered much about the potential health hazards in those days. We also once had to draw mercury up a pipette for a school science experiment - one guy sucked too hard and got some in his mouth !
Excellent video btw. I'm a retired electronics engineer a little older than Bruce so I'm aware of some of the simplifications but I don't think they matter too much if the basic ideas get across which is all that matters in this case.
Belper Flyer
Yes Bruce explains very well , its like having a private Tutor in Aeromodelling .
Was wondering what Hall effect was on my Taranis plus ltd edition.
Hope that boy had no ill effects from the Mercury incident!