opposite polarity what does it mean exactly

[hoarybat]

Hi all! Great forum first time here!  I too am going to give a magnet motor a whirl.  I do have one concern which maybe u could help with in RED below:  what does the highlight below mean exactly?  I am attempting to build my motor with repulsion (like poles facing).  Is opposite polarity = is N-N/S-S repulsion (same polarity) = de-magnitizing?  I don't wan't to kill the magnets because if it is turning for a while and slowly loses power, what good is it right?  My first prototype worked OK for a start and turned on its own but was too small to really get going fast.  I am investing to make it larger to increase the speed based on my design.  I am using permanent ceramic magnets first to test the theory since they were less $$ NeoD.  Below is 1 of 3 ways to demagnatize a magnet:

2) Via a demagnetizing magnetic field: permanent magnets exhibit a characteristic called coercivity, which is the ability of a material to withstand being demagnetized by an applied magnetic field. Modern permanent magnet materials such as Sm-Co and Nd-Fe-B have high coercivities; older materials such as Alnico or ceramic [hard ferrite] materials have lower coercivities. With a strong enough magnetic field of opposite polarity, it is therefore possible to demagnetize the magnet [whether this comes from another permanent magnet, or a solenoid]. Interestingly, an opposing magnetic field is sometimes applied to a magnet in order to 'knock it down', or to lower its overall magnetic output, so that it can be used appropriately in an application.

Many thanks in advance HB

[hoarybat]

Does anyone have an answer to help me?  Googled to death and can't find a correlation.

[poynt99]

hoarybat,

That is a typo.

It should read something like "opposing poles", meaning poles of the same polarity, i.e. in repulsion.

As mentioned, magnets with low coercivity have this problem of becoming demagnetized when used with opposing poles. With neos and SmCo mags, this should not be as much a problem, if at all, but I am not an expert on magnets.

If you have a choice, it might be wise to go with an attraction style motor then.

So you have a self-runner do you? Could you post a video please?

.99

[gyulasun]

Hi hoarybat,

Member Honk made a setup with opposing pole Neo magnets close to each other and after some months he could not find any flux loss from the magnets.  While this is a static case, you may ask what about the moving repel magnets close to each other, and whether eddy current will heat up the body of the metal magnets? (Your ceramic magnets are surely not prone to eddy currents.)

So the answer is this link here: http://www.overunity.com/index.php?topic=2751.msg56551#msg56551

See also Honk's thoughts here: http://www.overunity.com/index.php?topic=3456.msg56445#msg56445

Regarding your original question, I agree with poynt99, it must be a loose usage of words.

Any chance you may explain your working setup?

rgds, Gyula

[maw2432]

Hoarybat,

Do you have any photos of your working motor?

Bill