Great video thanks for your time and effort it is much appreciated. You are a great teacher! I know you did this years ago but your videos are helping an old fella get his head around electronics today.
So much positive feedback for negative feedback! The kids of my colleagues at work get a kick out of this each year during Bring Your Kids To Work Day. Thank you Shahriar!
man so cool...your description is so simple to understand. anyone with basic knowledge in electronic can make. you make it that so simple... There is complicated circuits for this but this one is simply the best..
OH.MY.ALLAH. I've been looking for a way to build an electromagnetic suspension device like this for so many days now! I was scratching my head and piecing together scraps of research but was getting increasingly frustrated - to the point of thinking of giving up.. You have seriously saved my life with this tutorial. Very informative and has everything I need. I'm an instant subscriber! You are helping to inspire and teach countless students young and old all over the world. Thank you.
Well, there's another one that you hit straight out of the ballpark. Super! Absolutely stupendous! If you're ever in Houston I'd be happy to buy you a beer! Thanks for all of your hard work.
As I have commented many other times, you are a good guy! it is so awesome and inspirational that you are giving back, it makes me want to be a better person... Back in the 90's I did a very similar magnetic levitation project as part of a controls class final project except we needed to do a full blown analog controller, as I recall it was much more complicated than your approach. Thanks again
A wonderful project and a top-notch explanation of the theory behind it!. Your videos are always instructive and entertaining. I really appreciate the effort.
Thanks. Watching your video always gives a high as if I am physically doing it. You clear the possible doubts on the way and is a very effective teacher.
Another great video. Instead of KA7500 you can also use TL494, AFAIK they are identical and both can be found in old computer psu, best way to recycle old parts.
I love the two Hall-effect sensor idea, that's genius. It appears as if you have damaged the two large electrolytic capacitors during your fine-tuning. the tops of them are obviously bulging after too much heat was generated internally.
Your videos are so creative and well explained. Who would ever have thought to use levitation as a lead in to understanding PLL's. Genius.......... Thanks
this helped explain hall effects pretty well. I'm currently trying to make a diy 500g-1kg (it be great if more) electro magnetic levitator with conventional metal infused PLA filaments with my 3d printer. its a very slow tedious process but im finally making some leeway in my current prototype demo thanks to this video. I need to find a real ferrite outter circle though for the 3d printed electromagnets (used electromagnetic filament for the base of the 4 electro magnets and copper wire wrapped around)Thank you!+thank you to all the commenters putting a lot of other equations here.
The system has feedback, it does not operate in open loop. In fact, it won't work in open loop at all. There is feedback around the error amplifier which goes all way the way through the electro-magnet, Hall-effect sensor before it is fed back to the error amplifier.
Thank you very much for your effort for making this very educational video. Your teaching style is innovative, not many people make cool projects and explain them.
I have to say that this video was absolutely awesome to say the least! To be honest, for some of your other videos, I have stopped watching after 10 minutes or so because they have been way too fast progressing, too complicated with advanced terminology and generally difficult to follow. This video was the complete opposite. Easy to follow and understand, which made it VERY interesting. Thank you.
Excellent experiment. Simply put : Food for the brain :). BTW I know students from the local university that follow your channel with 10x more dedication than all the courses they are having.
I absolutely love your videos and the way you can explain difficult subjects. im glad you're reaching a milestone in the amount of subscribers, that only means we get to enjoy more quality content. thank your Mr Shahriar.
Awesome video! One small correction - I think that the magnetic field very near to a magnetic dipole actually changes as 1/r^3, not 1/r^2. This is the due to the difference between a dipole and a monopole (like a point charge).
I was searching for someone to point this out as soon as I started watching. Worth noting that the cubic relation also makes control that much harder. Or put another way, the sensitivity of the control system is higher. That much harder to get the dampening right.
Of course, the force between two dipoles is even more complicated to calculate. There are multiple terms, though 1/r^2 terms are involved in most situations (unless the magnets are much smaller in scale compared to the separation, I think).
You are right. But what I meant is that the IC would work much better, as PWM controller, with some feedback at the error amplifiers. In open loop, with the near infinite gain, the amp works as a comparator and the system runs as bang bang control. The ringing inside the Ton time of the output square wave is the hysteresis loop working at the middle of bandwidth of the feedback loop.
Another great video. Much appreciated. You are in inspiration to so many - the 5k subscribers you mention at the end of the video is now 30k! Including me. :)
This system is barely stable. The open-loop transfer function is something like 1/(s^2 - 1), which has a pole in the right-hand plane. The negative feedback creates a closed-loop transfer function of 1/(s^2 - 1 + g), where g is your loop gain. This give a pair of complex poles on the y axis, which wouldn't normally be stable, except that you have a tiny amount of air resistance. If you differentiate the hall-effect signal and add that in your feedback loop, making the feedback path (g1 + g2*s) I believe if would improve stability by pushing the complex poles solidly into the left-hand plane.
Katia Gyetvai He's right though.. look at the oscillations... Also, his system is unstable because he uses a very simple regulator (most likely only P). If you use a properly tuned controller, such as PID, these problems will dissapear. I also doubt he did a simulation before that to check the transfer function.
I totally agree. But the problem then is to tune the system with the proper amount of differential gain to get stable response. In my experience designing one levitator that way, yes it gains marginally better stability at the expense of hours of tuning.
I did a project like this also two years ago for a class on instrumentation design. We used an arduino to read in the voltage from the hall effect. I wish I would have thought of a second sensor on top. the way we tried to cancel out the coil to cancel oscillations was to sample the sensor when the PWM was low (while trying to make sure the inductor was fully discharged) I have a couple videos of it in my channel if you want to check it out
Great video, really takes the snore out of my controls class and gives more intuition as to what and why i study controls. But if i do build this gadget i'd probably try to make it levitate using a knight rider effect on it. But again thanks for the inspiration and intuition, looking forward to more videos from you.
This is the best video on this project. I am building this right now so it's very useful. I have one question: Is it necessary to establish a PWM using an oscillator, or I can directly use the output of the op-amp to turn the electromagnet on/off? I don't have the KA7500C IC, was wondering if I can use something else instead if I understand what's needed..
The full schematic of the project is available on my website. All the part numbers are available and there is even a link on where to buy the electromagnet. The rest is up to you! :)
I am uncertain how well it work with something like that. It all depends on how much the steel ball influences the magnetic field going through the Hall effect sensor at the bottom, and I am not sure if it will have a strong effect on it.
Great video! I will propose this for Bring Your Kids To Work Day. I'm wondering, though, if having reverse current when the ferromagnetic attraction force exceeds m*g, would cause stability issues as pushing does not offer an equilibrium point in the 2 other directions as pulling does.
I really like those probes you have to convert the oscilloscope probes to something you can connect to a bread board ... any idea what they are called and where I might get some?
Excellent video. And excellent project. Congrats!! Would it be possible to omit the hall sensors and take the feedback from the tiny current that the magnet induces to the coil? Forgive my question I only understand a fraction of what You exposed... My understanding of electronics and circuits unfortunately is minimal... I have an idea of a project that I believe would be very interesting in aeronautics. ( I am only a naive and humble hobbyist ). Thank You and best regards. Victor Micha.
Great video but little correction, on 29:40 you describe that pwm is turned off that it do burst of pwm what is not case, what you describe as pwm burst are some oscillations in circuit (they are to high frequency to be from pwm), instead pause and what you describe as pwm bust are one pwm period.
Not really useless. As you can see in the single shots, the PWM is neither at 0 or 100% but somewhere in the middle (with ugly ringing). So it's doing PWM. But I don't know if there's any advantage in using the IC. Replace it with another opamp comparing the FBV and the set voltage and feed the output directly to the FET gate. Should be able to levitate the magnet and would be worth a try (oscillations could be a bigger problem with this setup though).
That's a pretty damned cool party trick :D I wonder if this might benefit from using a latching current mode PWM controller such as UC3843 rather than the very basic TL494 equivalent you have. You would have intrinsic cycle by cycle current limiting, so shouldn't need the big power resistors; have the latch to stop the multiple switching transitions per cycle you see on the scope; and the current loop which makes the electromagnet into a voltage controlled current source, taking its behaviour as an inductor out of the equation makes the whole thing intrinsically more stable and more tolerant to variations in loop compensation at the error amplifier. At least I know about this in switching power supplies, but I can only guess as to how well this translates to this circuit. I might try it but I don't have the magnets, electromagnet or hall effect sensors, so I probably will procrastinate and eventually forget about it.
This should also work with steel ball, right? Ball can rise a bit magnetic field at bottom so there must be little difference on exit of 741. This is amazing video. I wish that my uni. prof. were as good as 1/10 of you.
William, thanks for your observations. Would you please recommend some easy reading material that would give me a good understanding of poles,zeroes and how you saw that the stability would improve by pushing the complex poles solidly in the left hand plane? - Thx
Possibly a soft iron core would allow the magnet to approach quite closely, since the electromagnet field would be very low when it was largely unenergised. The steel has too much remnance.
How can I miss this video all these years. Elegant technique. And beautiful way to demonstrate control theory.
Great video thanks for your time and effort it is much appreciated. You are a great teacher! I know you did this years ago but your videos are helping an old fella get his head around electronics today.
So much positive feedback for negative feedback! The kids of my colleagues at work get a kick out of this each year during Bring Your Kids To Work Day. Thank you Shahriar!
This is one of the best tutorials I have ever seen. Thanks. You are a wonderful teacher.
man so cool...your description is so simple to understand. anyone with basic knowledge in electronic can make. you make it that so simple... There is complicated circuits for this but this one is simply the best..
OH.MY.ALLAH. I've been looking for a way to build an electromagnetic suspension device like this for so many days now! I was scratching my head and piecing together scraps of research but was getting increasingly frustrated - to the point of thinking of giving up.. You have seriously saved my life with this tutorial. Very informative and has everything I need. I'm an instant subscriber! You are helping to inspire and teach countless students young and old all over the world. Thank you.
Jeeeeebus
Well, there's another one that you hit straight out of the ballpark. Super! Absolutely stupendous! If you're ever in Houston I'd be happy to buy you a beer! Thanks for all of your hard work.
This is an excellent explanation, easy to understand without being too simple, and detailed enough without being confusing.
As I have commented many other times, you are a good guy! it is so awesome and inspirational that you are giving back, it makes me want to be a better person... Back in the 90's I did a very similar magnetic levitation project as part of a controls class final project except we needed to do a full blown analog controller, as I recall it was much more complicated than your approach. Thanks again
What a neat little experiment !
A wonderful project and a top-notch explanation of the theory behind it!. Your videos are always instructive and entertaining. I really appreciate the effort.
Thanks. Watching your video always gives a high as if I am physically doing it. You clear the possible doubts on the way and is a very effective teacher.
Another great video. Instead of KA7500 you can also use TL494, AFAIK they are identical and both can be found in old computer psu, best way to recycle old parts.
I love the two Hall-effect sensor idea, that's genius.
It appears as if you have damaged the two large electrolytic capacitors during your fine-tuning. the tops of them are obviously bulging after too much heat was generated internally.
Your videos are so creative and well explained. Who would ever have thought to use levitation as a lead in to understanding PLL's. Genius..........
Thanks
Great video. Thanks a lot. Best regards from Victor Micha. Mexico City. 🇲🇽
this helped explain hall effects pretty well. I'm currently trying to make a diy 500g-1kg (it be great if more) electro magnetic levitator with conventional metal infused PLA filaments with my 3d printer. its a very slow tedious process but im finally making some leeway in my current prototype demo thanks to this video. I need to find a real ferrite outter circle though for the 3d printed electromagnets (used electromagnetic filament for the base of the 4 electro magnets and copper wire wrapped around)Thank you!+thank you to all the commenters putting a lot of other equations here.
Great effort and thank you for such great videos - much appreciated!!!!
The system has feedback, it does not operate in open loop. In fact, it won't work in open loop at all. There is feedback around the error amplifier which goes all way the way through the electro-magnet, Hall-effect sensor before it is fed back to the error amplifier.
very high quality videos packed with clear explanations....and neat work.
you deserve a high quality thanks.
This is still a great video. Thanks 7 years after the fact.
Another excellent video, demonstrating principles very clearly and then a practical demo! Keep up the good work.
I LIKE THE SETUP!!!
Simple and easy
Explanation are great in every single video!!!
Keep up the good work
I am learning a lot thanks to your videos
Excellent video! Really well explained. You are a great engineer.
Awesome video, you are a big inspiration to me and I can imagine to many others.
Thank you very much for your effort for making this very educational video. Your teaching style is innovative, not many people make cool projects and explain them.
Thank you Signal path blog .Another really good video .
You keep me studying even when I'm trying to take a break!
I have to say that this video was absolutely awesome to say the least! To be honest, for some of your other videos, I have stopped watching after 10 minutes or so because they have been way too fast progressing, too complicated with advanced terminology and generally difficult to follow. This video was the complete opposite. Easy to follow and understand, which made it VERY interesting. Thank you.
Excellent Video!!!
Thank you, I really appreciate the way you take the time to explain the circuit and the build. Not many people do that !
Excellent experiment. Simply put : Food for the brain :).
BTW I know students from the local university that follow your channel with 10x more dedication than all the courses they are having.
I absolutely love your videos and the way you can explain difficult subjects. im glad you're reaching a milestone in the amount of subscribers, that only means we get to enjoy more quality content. thank your Mr Shahriar.
thanks for you valuable job on teaching guys how to make a circuit that really works. You are so great. I will build it for my self.
Awesome video! One small correction - I think that the magnetic field very near to a magnetic dipole actually changes as 1/r^3, not 1/r^2. This is the due to the difference between a dipole and a monopole (like a point charge).
I was searching for someone to point this out as soon as I started watching. Worth noting that the cubic relation also makes control that much harder. Or put another way, the sensitivity of the control system is higher. That much harder to get the dampening right.
Of course, the force between two dipoles is even more complicated to calculate. There are multiple terms, though 1/r^2 terms are involved in most situations (unless the magnets are much smaller in scale compared to the separation, I think).
Great video Thank you for all your inspiring ideas. Is it possible to get the schematics of the setup and the list of the parts used? Thanks again.
Excellent video.
Thank you.
There are of course many ways of doing this. The IC was available and provided an opportunity to introduce a new part people can learn about.
how do v do d same setup with the electromagnet on the table and things levitating over it?
You are right. But what I meant is that the IC would work much better, as PWM controller, with some feedback at the error amplifiers. In open loop, with the near infinite gain, the amp works as a comparator and the system runs as bang bang control. The ringing inside the Ton time of the output square wave is the hysteresis loop working at the middle of bandwidth of the feedback loop.
Neat. Can't wait for the future videos you are talking about.
Pfff, I could never imagine magic can be that awesome! To be honest, I kinda treat these topics as superfluous but when you do did it I was in awe
Amazing video, thank you!!
Excellent !!, enjoyed the video
Excellent! Another great tutorial from you!
Another great video. Much appreciated.
You are in inspiration to so many - the 5k subscribers you mention at the end of the video is now 30k! Including me. :)
As usual a very nice video. Thanks
Nice video on levitation!
Man i Loveeeeeeeeeeee this channel , thanks for the great explanations and tutorials , please keep up the good work , your fans from London .
from Bolivia SudAmerica thank you your videos are amazings!!!!!
Nice one! Good for teaching
👍👍
Great learning material!
Fantastic video. Very clear & informative. Now know what my next project is going to be
Keep up the good work :)
This system is barely stable. The open-loop transfer function is something like 1/(s^2 - 1), which has a pole in the right-hand plane. The negative feedback creates a closed-loop transfer function of 1/(s^2 - 1 + g), where g is your loop gain. This give a pair of complex poles on the y axis, which wouldn't normally be stable, except that you have a tiny amount of air resistance. If you differentiate the hall-effect signal and add that in your feedback loop, making the feedback path (g1 + g2*s) I believe if would improve stability by pushing the complex poles solidly into the left-hand plane.
Wow. So complicated William,
Katia Gyetvai
He's right though.. look at the oscillations... Also, his system is unstable because he uses a very simple regulator (most likely only P). If you use a properly tuned controller, such as PID, these problems will dissapear. I also doubt he did a simulation before that to check the transfer function.
I totally agree. But the problem then is to tune the system with the proper amount of differential gain to get stable response. In my experience designing one levitator that way, yes it gains marginally better stability at the expense of hours of tuning.
Good platform for developing a seismometric sensor.
Thanks for that. Your an excellent teacher, keep em coming.
Bravo! Excellent Electronics Video!
I will try this analog ciruit it is just GREAT!.....Thanks
Don't confess to understand it all but very interesting. Thank you.
I did a project like this also two years ago for a class on instrumentation design. We used an arduino to read in the voltage from the hall effect. I wish I would have thought of a second sensor on top. the way we tried to cancel out the coil to cancel oscillations was to sample the sensor when the PWM was low (while trying to make sure the inductor was fully discharged)
I have a couple videos of it in my channel if you want to check it out
Great video, really takes the snore out of my controls class and gives more intuition as to what and why i study controls. But if i do build this gadget i'd probably try to make it levitate using a knight rider effect on it. But again thanks for the inspiration and intuition, looking forward to more videos from you.
Great show. I sent it to my nephew to enjoy as well.
Great demonstration!
Awesome video and awesome teaching thanks!
Thanks my friend.
Thank you for the prompt reply.
This is such an interesting video. Thanks very much!!!
You are a very good teacher. Thank you..
Fantastic video, as we have come to expect :) Thanks very much.
Hey man, I've just found you yt channel, your videos are awesome, keep teaching us! Thanks!
This is the best video on this project. I am building this right now so it's very useful. I have one question: Is it necessary to establish a PWM using an oscillator, or I can directly use the output of the op-amp to turn the electromagnet on/off? I don't have the KA7500C IC, was wondering if I can use something else instead if I understand what's needed..
Great Job Man
Great Video! Very Informative!
The full schematic of the project is available on my website. All the part numbers are available and there is even a link on where to buy the electromagnet. The rest is up to you! :)
Great video as always, well done.
Great explanation.Thanks very much!
I am uncertain how well it work with something like that. It all depends on how much the steel ball influences the magnetic field going through the Hall effect sensor at the bottom, and I am not sure if it will have a strong effect on it.
As always, Excellent. Thanks.
I love your videos, you're such a good teacher.
I felt that I should tell you that =)
Really great, sometimes we forget the old fashion way of doing things without microcontrollers.
Many thanks for a super video.
Awsome looks sooo simple when u do it.
Great video! I will propose this for Bring Your Kids To Work Day. I'm wondering, though, if having reverse current when the ferromagnetic attraction force exceeds m*g, would cause stability issues as pushing does not offer an equilibrium point in the 2 other directions as pulling does.
good one. Nice.
Loved the video, brilliant
Great video, thank you!
I really like those probes you have to convert the oscilloscope probes to something you can connect to a bread board ... any idea what they are called and where I might get some?
Very interesting and informative, thanks,
Great video and very well explained Thanx I really enjoid that
Excellent video. And excellent project. Congrats!!
Would it be possible to omit the hall sensors and take the feedback from the tiny current that the magnet induces to the coil?
Forgive my question I only understand a fraction of what You exposed... My understanding of electronics and circuits unfortunately is minimal...
I have an idea of a project that I believe would be very interesting in aeronautics. ( I am only a naive and humble hobbyist ).
Thank You and best regards.
Victor Micha.
very well explained. Thanks.
Awesome video keep it up!
Loved the video.
Realy good job!
I enjoyed this video!
Great video but little correction, on 29:40 you describe that pwm is turned off that it do burst of pwm what is not case, what you describe as pwm burst are some oscillations in circuit (they are to high frequency to be from pwm), instead pause and what you describe as pwm bust are one pwm period.
Is that a reverse-biased (and bulging) cap I see on the top right? Also, fantastic video. The levitation worked better than I would have expected.
Not really useless. As you can see in the single shots, the PWM is neither at 0 or 100% but somewhere in the middle (with ugly ringing). So it's doing PWM.
But I don't know if there's any advantage in using the IC. Replace it with another opamp comparing the FBV and the set voltage and feed the output directly to the FET gate. Should be able to levitate the magnet and would be worth a try (oscillations could be a bigger problem with this setup though).
That's a pretty damned cool party trick :D
I wonder if this might benefit from using a latching current mode PWM controller such as UC3843 rather than the very basic TL494 equivalent you have. You would have intrinsic cycle by cycle current limiting, so shouldn't need the big power resistors; have the latch to stop the multiple switching transitions per cycle you see on the scope; and the current loop which makes the electromagnet into a voltage controlled current source, taking its behaviour as an inductor out of the equation makes the whole thing intrinsically more stable and more tolerant to variations in loop compensation at the error amplifier. At least I know about this in switching power supplies, but I can only guess as to how well this translates to this circuit. I might try it but I don't have the magnets, electromagnet or hall effect sensors, so I probably will procrastinate and eventually forget about it.
This should also work with steel ball, right? Ball can rise a bit magnetic field at bottom so there must be little difference on exit of 741.
This is amazing video. I wish that my uni. prof. were as good as 1/10 of you.
William, thanks for your observations. Would you please recommend some easy reading material that would give me a good understanding of poles,zeroes and how you saw that the stability would improve by pushing the complex poles solidly in the left hand plane? - Thx
Possibly a soft iron core would allow the magnet to approach quite closely, since the electromagnet field would be very low when it was largely unenergised. The steel has too much remnance.