Great Video, and thank you for not taking us on the visuals of each test. The analytical no nonsense to the point presentation needs a Gold Olympic medal.
Great demonstration of experiments to show the effects of eddy current drag. Keep up the good work as I’ve never seen these kinds of experiments with this topic to look at so many different variables. 😀👍
This is a seminal work in this subject matter -- especially for engineers who are curious about basic design elements for eddy current brake systems. Fantastic content, sir.
Thank you for the well-done presentation, it helped me a lot in finalizing the design and fabrication of my version of Eddy current water heating system for our home in floor heating
Nice testing. Very interesting. If you do another test series it would be interesting to note what the energy transfer efficiency is from the drill press to the copper plates. Would need to know the weight of each plate X delta T X specific heat X the time period. Since I experiment with building room heaters, that would be good info.
Nice test but picture net to the chart would help. Since I forget what you are talking about. Also I assume when you have some inconsistencies it might be due to frequency of the metal and speed.
Thanks - Yes - The one that that was hard to control precisely was the time - 10 seconds. I would spin the drill down and hit the timer at the same time but sometimes it might hit 11 seconds before I would raise it back up. Also, as the copper would heat up above the ambient air temp I think spinning it in the cooler air was cooling down the copper a bit after i had already ready the temperature. It worked well for the most part but a few inconsistencies means it was real data:)
Bismuth would be interesting but it is a different magnetic property:) Bismuth is diamagnetic and creates an opposite polarity above the magnetic fields. Pyrolytic Graphite is much lighter and has a much stronger diamagnetic effect. I might look at seeing what pyro does - if it is interesting - Hey it will be another video!!!! Thanks for the idea.
They sort of are. The clutch on the air conditioning is magnetically operated. As far as replacing the torque convertor you'll have a problem with heat. Eddy current is still a current. That current flow will create heat. A torque convertor has a fluid (oil) pumped through it. This fluid is run through a radiator to cool it. Even then when the car comes up to speed, the torque convertor "locks" out by directly connecting the drive shaft to the gearbox and stops the need for the fluid coupling. The fluid coupling seems rather mechanical but is actually very efficient. Eddy current is just resistive losses.
Visual is the best Teaching Method otherwise it doesn't hold the Minds Attention and the comparison with Aluminum might have been even more enlightening, just my opinion...
Great video- pretty exhaustive testing. What were those 1" magnets on the 6" disc array? For anyone curious of the speed of the copper passing over the magnets here are the ranges... 5"C : 15.707" travel 6"C : 18.849" travel A= @665rpm : ( 174.08"/sec - 208.90"/sec ) ( 59.26 : *B* ) ( 37.8% : C ) B= @1122rpm: ( 293.72"/sec - 352.47"/sec ) ( 168% : A ) ( 63.93% : C ) C= @1755rpm: ( 459.42"/sec - 551.33"/sec ) (263% : A ) ( 156% : B ) That is quite a change in response by air gap @16:10 of the video. ( edit in bold )
Yes - I realized I forgot to mention that:) They are 1 inch diameter (25.4 mm) x 0.25 inches thick N40.:). Thanks for giving the angular velocity - that is quite a drop in speed:)
Do two magnet behave like a magnet and copper with respect to eddy current drag? Do they attract or repel more when one is moving ? As in for example magnetic gear arrangements or even two magnets approaching each other?
Great video! just one little question: would the temperature test be more precise if the total amount of warmth was calculated? Because the masses of discs are different and it seems that it takes different quantity of warmth to increase their temperature. Also there are different quantities of work are done with different disks as well. So it seems like, in the same conditions, the temperature increasing should be proportional to the amount of work done and oppositely proportional to disks masses.
Andrew - sorry to be late in replying but - we plate the magnets and encapsulate magnets in plastics and PTFE and epoxies to reduce oxidation. The "rust" is the oxidation of the material. Great care is taken at every step in the manufacturing process to eliminate oxygen in the material but at the atomic level there will always be something in the material. The less oxygen that is entrained in the material the longer it takes before oxidation will affect anything about the magnet. I have had a customer who did get some of our high temperature magnets and molded clay around them and baked it in an oven to sinter the clay and it worked great. Since standard neodymium magnets are only good for an operating temperature of 60-80° you would need to probably select the SH grade neo which is good for 150*C or a samarium cobalt magnet that is good to 300°C. Thanks - I hope this helps.
I have huge magnets but currently no large blocks of copper. I really want to see the eddy currents effect. I have a bullion block of aluminium that surprisingly didn't work. Maybe it does but not as much as copper? Is that right? Also, I figured until I can afford a big block of copper, maybe a small bit of copper will work in a large magnetic field! No. No that doesn't work... 😆
Thank you for this video it was extremely helpful I have a question I built a generator with magnetic wire and n52 magnets I'm noticing the magnets are getting weak I produced a lot of current at first and now it's half the amount got any ideas n/s thanks
can you run a drag test with a north on one side and a south on the other sandwiching the copper plate and try doing and off set half over lap(like a zipper)
Really this is closely related to induction motors. This is basically a locked rotor test in disguise. Note that adding a (thin!) iron backing plate to the copper will usually give you much bigger braking effect because it closes the flux loop (but will also give you a net attractive force unless the amount of iron is very small). Also having two rows of magnets (alternating N-S side-side) will give much bigger effect- more than twice.
Sir..i have been trying to separate granulated electric wire lot to separate very thin granulated copper and plastic..with 1440 rpm rotation of magnets on conveyor belt..it is not showing any repulsion effect on 1mm x 4mm wire chunk moving on conveyor belt..my purpose is to separate copper from plastic..whats gone wrong..plz help me..thx.
I know you have great computer modeling, I have a configuration that I believe does create the equivalent of a Fresnel lense, only with magnetic fields, rather than light. The benefit, is that a lot less expensive magnetic material is needed, a positive there, also it has potential I believe to create incredibly strong permanent magnetic fields. Is there any chance you and your staff would evaluate this for me? Next, I am not looking to profit from this in any way, you can have all rights, etc.... The only thing I ask, "is that it be named after me, the lavedas configuration." If possible. I started working with permanent magnets at 3 yrs of age, where I encountered "numerical alphabet refrigerator magnets, that even at 3 I knew where different, and they were, the were very cheap, and used a Holbrook array configuration, in 1968-69, being three no one could ever explain said(we didn't have no www. Then!
I’m sure this is a good as the rest of your videos, but 10 minutes in and I’m so confused on exactly what you are doing…. I guess I should have watched the whole video. A visual on your setup on the drill press would have been helpful. Thanks for your videos, by the way.
Nice job on the experiments...love the enthusiasm in your work. I have a similar question...Have you or anyone out there...studied the effects of opposing magnet arrays? N S N S N ======= non-ferromagnetic conductive disk S N S N S versus N N N N N ======= non-ferromagnetic conductive disk S S S S S N S N S N ======= non-ferromagnetic conductive disk N S N S N I've built a resistance training sled with a 1/2" thick by 12" diameter aluminum disk that will spin over 1500 rpm (through a two step gearing process) at normal walking gait and I have 1" x 1" cylindrical RE magnets. Before I start machining a device to hold the array or arrays I'd like a little nudge in the right direction. *Are opposing arrays beneficial--- (provide considerably more eddy current resistance)?* Whether or not I use opposing arrays, I plan to be able to adjust the overall resistance by either changing - the air gap, or - the array's position relative to the distance from the center of the disk, or - how many magnets are actually positioned adjacent to the disk to create the magnetic field.
This is a terribly crude experiment. What if you used 1/2 inch disk magnets. The separation between magnets would make a bigger difference to the flux between the magnets. The sizes are a mess in this experiment.
