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Author Topic: Winding a strong electromagnet  (Read 178615 times)

Offline TinselKoala

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Re: Winding a strong electromagnet
« Reply #15 on: October 31, 2008, 02:04:58 PM »
@X: Picture hanging wire is generally steel (higher tensile strength) and is smaller in gauge or multi-stranded, here in North America. The soft iron wire is a general-purpose stuff usually sold in fairly large rolls (several pounds?) and is used for fencing, baling hay, concrete rebar tieing, anything you need a stout but formable wire for. I see that it is also called black iron wire.
When using it for cores it can be left bare, insulated with varnish, heat shrink, or any combo. You can also experiment with using the core itself as part of the circuitry, in whole or in part. Pack it tight, or even embed it in epoxy, to keep things from vibrating under AC stimulation.

EDIT to add there's a trade-off between number of turns and the added inductance. It isn't just resistance of the windings that is of concern. So there is an optimum number of turns, wire gauge, etc. for a particular core geometry and purpose (motor, transformer, choke, etc.) Electric motors and generators are remarkably efficient already and more efficiency would be a very strong sales incentive. IF motors could really be improved by reducing wire size and adding turns, beyond what has already been done, even just a little bit, it would be big news. Joe Newman's motors are remarkably inefficient flywheel energy storage systems; the main benefit from all that wire is the rotating mass it provides for the flywheel.

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Re: Winding a strong electromagnet
« Reply #15 on: October 31, 2008, 02:04:58 PM »

Offline capthook

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Re: Winding a strong electromagnet
« Reply #16 on: October 31, 2008, 05:34:28 PM »
@ CaptHook, how is it going.  I can totally relate to your frustration on finding high permeabilty materials.  I'm not sure about cold rolled steel?  Could you provide more information about it?  The permeabilty is most important....
I think the best material is silicon electrical steel which is very common but manufacturers will only sell to buyers with LARGE orders.  If you can salvage the cores from used transformers or inductors you could obtain the material, but I'm not sure how to do this.

 think the best material is silicon electrical steel which is very common but manufacturers will only sell to buyers with LARGE orders.  If you can salvage the cores from used transformers or inductors you could obtain the material, but I'm not sure how to do this.


Cold rolled steel:
http://www.ussteel.com/corp/sheet/cr/mls.htm
http://www.coilgun.info/theorymath/home.htm
Maximum permeability: 2,000u

Silicon electrical steel:  I second your motion and also wonder where to source a small, inexpensive, rod shaped piece !?!?

Offline Xaverius

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Re: Winding a strong electromagnet
« Reply #17 on: October 31, 2008, 06:58:05 PM »
@X: Picture hanging wire is generally steel (higher tensile strength) and is smaller in gauge or multi-stranded, here in North America. The soft iron wire is a general-purpose stuff usually sold in fairly large rolls (several pounds?) and is used for fencing, baling hay, concrete rebar tieing, anything you need a stout but formable wire for. I see that it is also called black iron wire.
When using it for cores it can be left bare, insulated with varnish, heat shrink, or any combo. You can also experiment with using the core itself as part of the circuitry, in whole or in part. Pack it tight, or even embed it in epoxy, to keep things from vibrating under AC stimulation.

EDIT to add there's a trade-off between number of turns and the added inductance. It isn't just resistance of the windings that is of concern. So there is an optimum number of turns, wire gauge, etc. for a particular core geometry and purpose (motor, transformer, choke, etc.) Electric motors and generators are remarkably efficient already and more efficiency would be a very strong sales incentive. IF motors could really be improved by reducing wire size and adding turns, beyond what has already been done, even just a little bit, it would be big news. Joe Newman's motors are remarkably inefficient flywheel energy storage systems; the main benefit from all that wire is the rotating mass it provides for the flywheel.

Hi, I have a lot of picture hanging wire here in my gallery.  I am familiar with baling wire, rebar wire, etc. so now I know what to look for.  I hope it is more permeable than ordinary hardware(nails, screws, bolts).  Enamel spray paint would be my insulator of choice with wire bundles to reduce eddy currents and Reactance.

You're right, motors are now extremely efficient, approaching 100% in most cases.  This has to do primarily with rising electricity prices  and using motors in small places such as electric razors, cd drives etc.  In my experience there are already some small motors(primarily DC) that are overunity.  For a given amount of electrical input, the mechanical output is greater.  What is very frustrating is that most small motors don't give their rated output, but if you search Data Sheets for small motors you can sometimes find the information.  The larger motors, used for compressors, pumps, etc. usually have a horsepower rating but I've never found any that are overunity.  It seems the larger the motor,  the less efficient but the greater output in absolute terms.

Free Energy | searching for free energy and discussing free energy

Re: Winding a strong electromagnet
« Reply #17 on: October 31, 2008, 06:58:05 PM »
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Offline Xaverius

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Re: Winding a strong electromagnet
« Reply #18 on: October 31, 2008, 07:11:24 PM »
Cold rolled steel:
http://www.ussteel.com/corp/sheet/cr/mls.htm
http://www.coilgun.info/theorymath/home.htm
Maximum permeability: 2,000u

Silicon electrical steel:  I second your motion and also wonder where to source a small, inexpensive, rod shaped piece !?!?
I see cold rolled is the same as silicon electrical.  Like I say you can salvage core material from used motors and transformers, but obtaining the right size might be difficult because these cores are machined to a particular shape.  Also have you tried ScientificAlloy.net?  You'll have to telephone them before 5:00 P.M central time and talk to a salesman.  They quoted me $250.00 for pure iron, ask them about EM core material.

Offline mondrasek

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Re: Winding a strong electromagnet
« Reply #19 on: November 01, 2008, 08:34:10 PM »
I know this might step off topic, but I've got to ask...

Say you are to make an electromagnet where you use a great number of single turn conductors wired in parallel.  Does this create an EM with nearly zero resistance, reactance, and impedance?  What kind of capacitance would such a device have compared to one of an equal number of turns wound from only one continuous conductor?

M.

Free Energy | searching for free energy and discussing free energy

Re: Winding a strong electromagnet
« Reply #19 on: November 01, 2008, 08:34:10 PM »
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Offline Kator01

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Re: Winding a strong electromagnet
« Reply #20 on: November 01, 2008, 09:23:25 PM »
Hey capthook,

this google-book link returns a message that this link does not exist.

Regards

Kator

Offline capthook

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Re: Winding a strong electromagnet
« Reply #21 on: November 02, 2008, 02:49:19 AM »
It appears the ultimate core material could be metglass?

http://www.metglas.com/products/page5_1_2_4.htm

Maximum DC Permeability (µ):
As Cast: 45,000
Annealed (High Freq.): 600,000

Saturation Induction (Tesla)   
As Cast: 1.56

Supposedly very expensive.....

"The material with the highest magnetic permeability is Metglas Magnetic Alloy 2714A (Cobalt-based) [7] with a high frequency annealed permeability of 1,000,000 (Maximum DC Permeability (µ)). "

I guess you would have to laminate numerous thin sheets together to make a larger core (or find a company that does that?!?)

This seems beyond my scope at this point.....

Sourcing ANY of the 'fancy' materials is expensive and difficult.  Also - getting them in an easily-usable form seems non-existant (as in solid rod form).
I'm of the notion that an EM core does NOT need to be laminated - and that a solid core would actually produce the best results.

Grain orientated silicon steel (electrical steel) seems a more practical option/the next-best option.

Looking forward to recieving ferrite rods next week for testing.....

Any other ideas/sourcing for other high permeability, practical core material?
Something like a .5" x 3" grain oriented silicon steel rod?

Also - going to the University next week for some research/reading materials.....
- - -
I think the best material is silicon electrical steel which is very common but manufacturers will only sell to buyers with LARGE orders.  If you can salvage the cores from used transformers or inductors you could obtain the material, but I'm not sure how to do this.

Me either!  But I would like to find out!

You might try ScientificAlloys.net.  They have a variety of materials and their sales personnel can provide information. 

I will call them Monday.
« Last Edit: November 02, 2008, 03:21:44 AM by capthook »

Free Energy | searching for free energy and discussing free energy

Re: Winding a strong electromagnet
« Reply #21 on: November 02, 2008, 02:49:19 AM »
Sponsored links:




Offline Xaverius

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Re: Winding a strong electromagnet
« Reply #22 on: November 02, 2008, 08:54:53 AM »
I know this might step off topic, but I've got to ask...

Say you are to make an electromagnet where you use a great number of single turn conductors wired in parallel.  Does this create an EM with nearly zero resistance, reactance, and impedance?  What kind of capacitance would such a device have compared to one of an equal number of turns wound from only one continuous conductor?

M.

The more single turn conductors wired in parallel, the closer to zero the resistance, reactance, impedance.  The capacitance would be the same with an equal number of turns from the same conductor.  You can use the Medhurst formula.

Offline Xaverius

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Re: Winding a strong electromagnet
« Reply #23 on: November 02, 2008, 09:03:31 AM »
It appears the ultimate core material could be metglass?

http://www.metglas.com/products/page5_1_2_4.htm

Maximum DC Permeability (µ):
As Cast: 45,000
Annealed (High Freq.): 600,000

Saturation Induction (Tesla)   
As Cast: 1.56

Supposedly very expensive.....

"The material with the highest magnetic permeability is Metglas Magnetic Alloy 2714A (Cobalt-based) [7] with a high frequency annealed permeability of 1,000,000 (Maximum DC Permeability (µ)). "

I guess you would have to laminate numerous thin sheets together to make a larger core (or find a company that does that?!?)

This seems beyond my scope at this point.....

Sourcing ANY of the 'fancy' materials is expensive and difficult.  Also - getting them in an easily-usable form seems non-existant (as in solid rod form).
I'm of the notion that an EM core does NOT need to be laminated - and that a solid core would actually produce the best results.

Grain orientated silicon steel (electrical steel) seems a more practical option/the next-best option.

Looking forward to recieving ferrite rods next week for testing.....

Any other ideas/sourcing for other high permeability, practical core material?
Something like a .5" x 3" grain oriented silicon steel rod?

Also - going to the University next week for some research/reading materials.....
- - -
Me either!  But I would like to find out!

I will call them Monday.

Some of the more exotic materials such as Metglas, SuperMalloy, etc have extremely high permeablities but relatively low saturation points(.25-.5 Tesla). Metglas can be purchased as a spool of ribbon but I priced it on Ebay for $125.00 for 50 feet.  It is also very sharp so it's difficult to handle.  I tried thin strips of GIron which is similar material and it didn't perform at all, I think these materials are only magnetized along the plane of the material(normally used for magnetic shielding) so I don't have a lot of confidence in using them. 

If you have access to a Sabre Saw with a metal cutting blade you might be able to obtain electrical steel laminations from salvaged objects.  You'll need it to cut the core material into the desired lengths/shapes.  I've heard old washing machine motors have cores that are easily used.  Might be worth trying.

If you don't use laminated steel or ferrite, the Reactance will be much greater.  If this is not a factor in your design then no problem, but if amperage optimization is important then you must consider using them.

Free Energy | searching for free energy and discussing free energy

Re: Winding a strong electromagnet
« Reply #23 on: November 02, 2008, 09:03:31 AM »
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Offline Kator01

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Re: Winding a strong electromagnet
« Reply #24 on: November 03, 2008, 01:02:26 AM »
Hello All,

here a good website from australia :

http://www.magneticsolutions.com.au/

@capthook: Some Killerrobot is obviously observing certain activities. I was accessing the patent-link

http://www.pat2pdf.org/patents/pat3670189.pdf

and downloaded the Pdf-File. A minute later accessing the same link again ( I had closed the window after download ) an error-message popped up saying that the file has been removed.

Regards

Kator

Offline gyulasun

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Re: Winding a strong electromagnet
« Reply #25 on: November 03, 2008, 01:25:09 AM »
Hi capthook,

Thanks for your P.Message. I think most of the aspects of making a good electromagnet have been included in this and in some other threads, I cannot add much new ideas unfortunately. Thanks also for quoting one of my earlier text on this subject earlier in this thread.
Some additional thoughts: I agree with Honk by saying that solid pure iron should be used with caution because of the eddy currents (unless you do not pulse-operate your EM),  see his thoughts: http://www.overunity.com/index.php?topic=2222.msg135629#msg135629 and here:
http://www.overunity.com/index.php?topic=5279.msg118679#msg118679
Also an important thing on response timewhen you do pulse the EM: http://www.overunity.com/index.php?topic=4948.msg105636#msg105636

You maybe noticed member DMMPOWER electromagnet offer? see here http://www.overunity.com/index.php?topic=4624.msg96814#msg96814
This reminds me to Jack Hildenbrand magnet valve but unfortunately DMMPOWER does not give any hint on the construction...   By the way, there is (I think) a valid argument against combining an EM with a permanent magnet to increase the flux by saying you can make the same increased flux by choosing a core with bigger permeability...
Well, this can be true up to a limit in the budget or fast switching speed or simply using already the highest exotic permeability core above which there is no higher and still you can increase the flux by including the flux from a perm. magnet too...

Thanks,  Gyula


Free Energy | searching for free energy and discussing free energy

Re: Winding a strong electromagnet
« Reply #25 on: November 03, 2008, 01:25:09 AM »
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Offline capthook

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Re: Winding a strong electromagnet
« Reply #26 on: November 03, 2008, 07:16:45 AM »
Gyula-

Thanks so much for the reply!  As always - your input is HIGHLY valued and most excellent!

By the way, there is (I think) a valid argument against combining an EM with a permanent magnet to increase the flux by saying you can make the same increased flux by choosing a core with bigger permeability...
Well, this can be true up to a limit in the budget or fast switching speed or simply using already the highest exotic permeability core above which there is no higher and still you can increase the flux by including the flux from a perm. magnet too...

Thanks,  Gyula

Agree.  From several text-books, as well as recent hands-on tests, adding a permanent magnet(PM) is helpful in that the PM can greatly multiply the relative force of the EM.
I can't provide exact figures, but...

Example in non-exact terms:
Supply an EM with 5 watts you get 1000 gauss.
Now take a permanent magnet with 1000 gauss and attach to the far end of the EM.
Apply the same 5 watts to EM.
You now end up with (1000+1000)x4= 8,000 gauss.
So you have greatly increased the efficiency of that 5 watts of power.

"If we have a certain number of magnetic lines, N, the pull is proportional to N(squared).
So the more powerful the pull to begin with, the greater is the change of pull when you produce a small change in the number of magnetic lines."

I see it as: it takes A watts to produce the needed flux from the EM.
Attaching a PM provides B watts of equivalent flux.
A-(Bx2)= C, the watts now needed to produce the needed flux.
The PM has 'pre-charged' the EM for free by 'pre-aligning' some of the magnetic domains.

Once again - I don't know the exact relative effect - is it 4x or 8x or x2?  Wish I knew - but it is large.  One reference book states it as x2.

Also - as in my project - if you are (only) repulsing a PM with the EM, it is an additional benefit by nullifying/reducing the attraction of the PM to the EM core.

Honks points are good ones on eddy currents and hysteresis losses (which points again to laminated electric steel as the core of choice), and I still need to learn more about these as well as reactance.

As to powdered cores, what I've found thus far is that most have them have low permability (20-150u) and saturation points and would be inferior in most designs over laminated electrical steel.

I'm still reading through the full threads of the links you gave....
Still reading the interesting Hilden motor thread: http://www.overunity.com/index.php?topic=2222.0
and this: http://www.overunity.com/index.php?topic=3456.0

- -
As to metglas, permalloy etc... it seems the super high permeabilities translates into excellent shielding - but not as EM or generator cores.  As Xaverius mentions, I think it has to do with low saturation points, as well as their 'orientations'.

It seems the practical/efficient core solution is electrical steel - grain-oriented even being the best.
Ferrite cores might also be a good choice, depending on the application.  I'll know more first hand info next week...

- -
Ways to source scrap laminated electrical steel:

Old microwave: http://www.overunity.com/index.php?topic=4047.msg101636#msg101636 \

"You can also get good laminations from junked alternators." wattsup


So much to learn - so little time!  One little step after the other  :)


Offline Kator01

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Re: Winding a strong electromagnet
« Reply #27 on: November 04, 2008, 04:54:54 PM »
Hi capthook,

I would be very interested in reading this electromagent-book. Can you please review your link ?
It is no valid. No such book exists in this library.

http://books.google.com/books/pdf/The_Electromagnet__and_Electromagnetic_M.pdf?id=CLmFTg_j0pwC&output=pdf&sig=ACfU3U3SDSRbaHhRwpQzx6pb7kwk3pCBuA

Do you have a copy saved ?


Regards

Kator01

Offline mondrasek

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Re: Winding a strong electromagnet
« Reply #28 on: November 04, 2008, 05:40:16 PM »
Kator01,

Link works for me.  Book is ~11.8Mb which is over my outgoing e-mail limit here at work or I'd offer to send it to you.

M.

Offline Kator01

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Re: Winding a strong electromagnet
« Reply #29 on: November 04, 2008, 09:23:12 PM »
Hi mondrasek,

thank you anyway... but this is strange. Must be somthing wrong with the german-google-books-database.

Regards

Kator01

 

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