# Questions tagged [magnets]

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### Why do rare-earth permanent magnets need to be recycled instead of just reused?

For years, scientists and engineers have struggled to find ways to efficiently break down and recycle rare-earth materials from various devices, especially permanent magnets.... My question is: Why do ...
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### Would this be the best permanent magnet design for vertical rod?

I'm trying to design and build a small vertical wind turbine that is held in place by permanent magnets, i.e. the rod with the blades on is held using magnets and gravity and allows the rod (that the ...
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### How this synchronous motor works and how to modify them?

I have the following synchronous motor ripped out from an old range hood in my kitchen. I used new electrician tape to cover up the coils that should form the electromagnet--the old cover is too oily....
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### What is the most efficient way to convert shaking/vibration to electrivity?

What is the most efficient way to get electricity from shaking? I am thinking about something like shown in the picture below (the magnet is going inside the coil), but maybe there is a better design ...
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### How does the magnet sheet sliding metal mechanism work?

I was watching this video - at 10:23 mark where the person was using a hook mechanism for sliding the metal sheets together and noted that sometimes the hook would get caught on a bad angle. To solve ...
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### Magnetic Force - Point of Load

I am using a Magnet like this in an assembly and I am trying to calculate the torque in point P2 (see picture below) resulting from the attraction force F between my magnet and the steel part. As I ...
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1 answer
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### Can the repelling force of magnets be used to create heat energy thus maybe creating a tyoe of heat generator [closed]

Imagine holding two magnets in the opposite polar the force it creates is so powerful what happens if we hold someting in between and the force only gets stronger if you push but what if we get a ...
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1 answer
32 views

### Use magnetic levitation to lift a carousel capable of turning 9000lbs [closed]

Allow me to describe my current situation. I have a 18 ft (5.486 m) carousel that is assembled using steel beams that are bent into two circles, an outer and an inner. And there are steel spokes ...
1 vote
3 answers
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### What Goes Into Making a Variable Field Magnetic Motor?

(I feel it is necessary to mention that I am not an electrical or mechanical engineer; I just like to build fun things.) I've already got a good explanation of the concepts involved in a variable ...
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### Rotating a lead screw with a moving magnet

Is it possible to introduce torque on a lead screw (with no magnets attached to it) with a moving magnet that can only move parallels to the screw? (the lead screw is ferromagnetic) Something like ...
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### Looking for a compression spring alternative with 10x lifespan

I'm working on a project where 100k spring cycles is gonna last a few months Any recommendations on an alternative? I considered magnets but their sprigabilty isn't great (also, will they get ...
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### Can you make the magnets rotate inside the coils of Brushless motor?

I know that current brushless motors, have a non rotating core made of copper coils, with permanent magnets on the outside rotating around it, and eventually connected to a shaft. But i was wondering,...
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### Practical estimation of magnetic force

I'm trying to estimate the magnetic force which develops on a truss-like ferromagnetic structure (I want to estimate the motion of the object) in a uniform magnetic field, and I came to realize that I ...
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### Cheap / Easy source of small amount of ferromagnetic metal [closed]

Hello all I have a magnet in my car to stick my phone to the dashboard. But I changed phone and now my new phone needs some metal stuck to the case in order to attract to the magnet. I read online ...
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### Demagnetize neodymium permanent magnets at < 60 degrees C

I have 10 cylindrical neodymium permanent magnets about 5mm in diameter, 5 mm long, embedded in a thermoplastic polymer. I want to demagnetize them without removing them, or heating them above 60 C ...
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1 answer
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### Designing a "ratcheting" spinning wheel with ferrous metal bits

I'm trying to design a freely spinning wheel that will "lock" into a few different configurations. I'm planning on placing a rare earth magnet near a certain point on the wheel, and inserting bits of ...
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2 answers
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### How to design a magnet to handle a known force?

There is a metallical structure. I can estimate how much steel are in it. I would like to know how tall/strong a magnet should be to maintain a certain object to the metallical structure. The object ...
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2 answers
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### How do I add magnets to the mechanism of my exercise bike?

I have an exercise bike that works by a (I'm assuming solid iron) flywheel and a 'horseshoe' of magnets that are moved in and out to set the difficulty. I have attached an image of the same design ...
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4 votes
1 answer
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### Can a Foucault's current brake be used on the rails themselves to brake trains?

Your typical Foucault's current brakes operate on a disk, which is placed in an electromagnetic field in order to transform kinetic energy into heat without friction. The problem is that the disk ...
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### Can you use an electromagnet to break the connection of a permanent magnet?

At first, I had a particular goal, but I'm starting to doubt feasibility which has led me here. Original Goal: Create a small (3in²) electromagnet with 100% duty cycle capable of holding at least ...
1 vote
1 answer
118 views

### Can magnetic stripes be read wirelessly with lasers or other technologies?

I know that magnetic stripes used in credit cards and audio tapes are typically read by a magnetic reader head. But is it theoretically possible for the stripe to be read by a laser in a similar ...
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### Restricted Rotation using electromagnets

I was wondering if I could restrict the rotation of a part over another in one direction alone using an electromagnet but allowing me to have a continuous rotation if forced (maybe by using some ...
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### Is it possible to protect electronics on a cubesat from 100-1000g of acceleration

I am currently researching the feasibility of setting up a coilgun that launches Cubesats for a paper.
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### Difference between permanent magnet and electromagnet exciter generator in principles wise?

I searched about this, but couldn't find any helpful explanations. All it says is that magnetic field is generated by either permanent magnets or electromagnets. In both cases, how does the exciter ...
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### Compensating for a magnet in a device with a magnetometer

I'm working on a device that relies on data from a magnetometer. Unfortunately, the device also needs to have a fairly powerful magnet on it. Given that the design is fairly flexible, and within ...
2 votes
2 answers
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### How do I separate these powerful magnets from their base plates?

Old hard drives are my favourite source of super-powered fridge magnets. I have a bunch of them holding up countless childrens' drawings. But the magnets themselves are stuck to base plates of various ...
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### Is martensitic steel 455 magnetic?

According to wikipedia there are 3 types of steel based on the crystal structure: austenitic, ferritic and martensitic. Austenitic steels are non-magnetic where 300 series stainless steels belong to. ...
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### Does the Hyperloop One suspension require constant current through copper windings?

As a follow-up to How does the pressurized suspension of the Hyperloop not affect the tube pressure?, I believe (though I can't find where I read it now) that the Virgin Hyperloop One implementation ...
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### Could we use NE 555 Timer for industrial magnetic proximity switching circuit?

I actually need a magnetic proximity switching circuit such that In the case of water in fuel sensor, whenever the water level in water in fuel sensor increases the magnetic float shall move and come ...
2 votes
1 answer
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### Can a neutrally bouyant helium balloon be suspended in air using magnet entrapment?

The above picture is a basic concept of how a levitron toy works. Could the top floating peace stay entrapped in the magnetic field without having to spin if the edges of the balloon keep the top ...
2 votes
1 answer
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### Generating practical power without an iron core, but with high RPM

Here's what I'm proposing - a small turbine directly coupled to a permanent magnet that's spinning at, say, 150k RPM. The magnet is enclosed one or several wire loops parallel to the axis of rotation. ...
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### Magnetic Entrapped Storage at 0 gravity

I understand this is a multifaceted question and I apologize . All of it is relevant to be understood. On Earth Fly wheel storage devices are used as an alternative to batteries. Even with magnetic ...
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### How can I calculate field strength of a Neodymium Ring magnet at an angle?

How can I calculate field strength of a Neodymium Ring magnet at an angle? I have a Neodymium Ring magnet, and I rotate the magnet around an axis perpendicular to the poles. (Not continuous rotation). ...
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### Could a magnetic audio tape recorder/player be made using a vibrating permanent magnet?

Cassette tape players use a read head where the magnetic field from the tape is directed through an induction coil. The induced current in the coil is then amplified and sent to the speakers. Now I'm ...
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### Calculate the relative pulling force as function of size for neodymium magnets

I want to optimise the size and shape of a magnet for a desired pulling force. (Please forgive my limited knowledge of magnetism). A cylindrical magnet fixed to an object will hold it in place by ...
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### Effect of magnetic field on electronic components

Are electronic components like diodes,transistors, micro-controllers, microprocessors, wireless transceivers etc are damaged by strong static or dynamic magnetic fields? If yes, at what strength the ...
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3 votes
2 answers
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### How to split mercury with a magnetic force?

Do you think, one could split a mercury drop into two drops with the magnetic force? Mercury is a liquid metal, hence if I put a current through it, it will become a electromagnet (a wire with a ...
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### Magnetic decoupling torque

I have a system consisting of 4 magnets rotating at speeds between 200 and 6,000rpm, which are facing 4 other magnets with a 0.5mm gap between the two sets. The set-up looks like this: Both sets of ...
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1 vote
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### why is the outside of an electromagnet not magnetic?

On the electromagnet setup pictured below, only the core part is magnetic (when powered, it attracts a piece of steel) but not the 2 "wings" outside that are supposed to channel the magnetic flux. ...
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### Is there a device like this? [closed]

I would like to get my hands on a mechanically-set timer (wind up is fine, so that it's self-powered) which sends a small electrical pulse to a mag-lock once the timer goes off, thus causing the mag-...
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### 3D Representation of Magnetic Field Lines

There are several tools available for monitoring electrical metrics (voltage, current, resistance, frequency). I have recently acquired all that I need for these studies. What tools are available for ...
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### Under what circumstances would one need or not need an electronic brake for a permanent magnet motor?

My company was asked to design a custom product several years ago. The original requester never bought it, but we've sold several a year through distribution. It's been a small side-line for a while, ...
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### How does a Levitron work?

I just watched this video: https://www.facebook.com/HigherPerspective/videos/1162007547164896/ I don't understand what I see. If the spinner's magnetic, the bowl is made of iron and that the wood ...
1 vote
1 answer
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### Making a strong electro magnet

I am looking into making a strong electro magnet. I want it to be able to hold around 100 pounds of weight or more. Would a magnetic core like this work at all? I'm planning on wrapping wire around ...
2 votes
3 answers
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### How to form a seal around a sharp moving blade?

I have a setup where I want to move a knife like blade through a body of liquid inside a container and I want to control the blade from outside the container. Apart from using magnets to move the ...
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1 answer
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### How to 'smooth/flatten' the surface of a disturbed liquid without contacting it?

I would like to essentially flatten or smooth the surface of a viscous liquid after dropping an object into it, without actually touching the liquid. For example, if I drop a rock into a tub of oil, I ...
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1 answer
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### How to calculate the maximum spacing between Hemholtz coils?

I would like to design a long, uniform magnetic field using Hemholtz coils but am not sure how far I can separate them before the field lines diverge and become two loops that go around each coil ...
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### Can a magnetic lock be negated or overcome by a stronger electromagnet?

Magnetic locks seem to be fairly common on the doors of modern buildings, but I question their reliability when compared to a traditional, mechanical lock. I realize that the strength that it would ...
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### Live motion simulation with respect to electromagnetic field software

Totally numb question from non-engineer, so sorry about that. For my little home project I need to create a matrix of solenoids, so I need some kind of simulation. I wish to be able to create metal ...
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### Using magnetic field readings for linear gesture recognition

I am thinking about using a permanent magnet as an input device for my smartphone. I have been reading some papers about it, but I really want to understand how things work. Using the integrated ...