Magnet Core Solenoid?

[TechStuf]

If I have a 2 inch long X 1/2 inch diameter cylindrical N42 NDFEB magnet, can I surround it with a coil for the purpose of NEUTRALIZING it's field very briefly with a pulse of current???

Arringtj, I happen to own a digital camera with an NdFeB flash catch which does just that....at least for the purpose of releasing the flash arm.  I also own a handful of the NdFeB magnets you mention and their fields can also be "neutralized" or more accurately, 'shunted', via similar method.

Ergo stated:

It's not possible to alter the flux of a NdFeb magnet by a surrounding coil.
It would take an extremely heavy duty magnetizing force to affect the magnet.
But the heavy force would also demagnetize the ndFeb at the same time.

This idea is flawed and will not work.

Said the parrot on the shoulder of the man with the tenured eye patch.  There are numerous methods by which to alter the path and density of the flux quanta surrounding an NdFeB magnet.  An EM coil is certainly one of those.


Why, just the other day I gingerly waved a piece of iron in the face of a mean, stubborn old Neo, and it got all bent out of shape....and that lowly piece of fickle ferrousness was hardly pulsating with heavy force at the time.


TS

[khabe]

I took apart today one car starter solenoid. Outer case was OD-52mm, ID-44mm
not welded tube and tried on the Lathe - very well machinable and looks like
Nickel contents. Sizes do not fit exact I need. Its very hard to find or ask if you
dont know exact type or mark of steel you need, or how its called ...
One possibility is to visit scrap store and perhaps find right size starter solenoid ..
... unfortunately Im little bid ill right now and my back causes pain as well

Anyone has info about

With due respect,
khabe

[z.monkey]

I am building a solenoid based transformer now.

It is 2 inches long and about 0.85 inches in diameter.

It is the primary core for the Flapjack coil, here's the link...

http://www.overunity.com/index.php?topic=6640.0

It uses a soft iron tube and a 1/2" machine screw for the core.

After thinking about arringtj's idea I decided to make a second
primary coil with the NdFeB Magnets.  This web site sells some
0.75 inch ring magnets which I could stack up to make the core.

http://www.magcraft.com/products/ring/index.html

The rings are 1/4" tall so I stack up 8 and there is the NdFeB core.
I'll use a 3/8" machine screw to hold the core together and epoxy a
22 AWG winding to the outside diameter of the NdFeB magnets.

Thanks arringtj...

Edit:  The NdFeB ring magnets are 0.125 inches tall so I will need
16 of them to make a 2 inch stack.  At Magcraft's prices this is $27
plus shipping to make a 2.25 inch tall core.  That is pricey...

[X00013]

@ arring          as stated before, overcoming a neo with a wrap will be futile, i think what you might be looking for is somthing like this, take your .5 x 2 inch neo and place it end to end with same size isoferrite, then wrap the iso which has  low permabilty, the iso will flop poles via the neo and as you apply current to the wrap, only side effect will be they will fly apart when current is applied (simple enginnering problem),  hope this helps and good luck .

[Low-Q]

EM guru question:

I am not building a PM Spiral / Sprain motor, but similar end magnet issue...
Given: Pole faces are 90 degrees to each other, not face to face... and magnet wire would be closer to other PM's than core.

If I have a 2 inch long X 1/2 inch diameter cylindrical N42 NDFEB magnet, can I surround it with a coil for the purpose of NEUTRALIZING it's field very briefly with a pulse of current???

Can the coil be "seen" by other PM's as the opposite polarity if current is opposite of core polarity?

What would a brief pulse of HF AC do in this coil?

Many thanks for any expert input!

Jeff

You can use a magnet as an electromagnet core. The difference is that the core this time has an magnetic offset. The energy you put in to the magnetwire will accordlingly reduce the total magnetic field of the magnet. However, the change in magnetic field is allways less than the energy you put in to the magnet wire. So if you want to make a OU magnetmotor based on magnet cores, you will probaly meet a dead end. But it's worth trying anyway for learning purpose.

Vidar