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Author Topic: Tesla's "COIL FOR ELECTRO-MAGNETS".  (Read 505792 times)

Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #240 on: May 27, 2013, 04:09:17 AM »
Hey Mags,

Is it not logical to expect that some lifter designs may use multiple coils as a way to increase ampere turns for more lifting power or to allow for a more physically compact unit?  Any increase in DC resistance can be compensated for via application of a higher DC voltage to maintain a given DC current.

Heating of the windings is usually a limiting factor with these lifters, and you will note that the mfg page cited specifies a 75% or so duty cycle for most of their lifters.

I just don't see anything in that 1914 image that is not consistent with a standard DC lifter. 

PW

Hey Pico

Im just stating what I read and see.  The page of the pic I posted says flat conductors. And so does the modern magnet link claim this in the repair section.

Of the 2, the pic posted seems to have 4 layers if Im interpreting the cut away view properly. And the pics of the repair coils look as to have 2 layers, like pancakes made of flat conductors and stacked ready for butter and syrup. Possibly they are in series with each other, dont know yet.  Just laying out what I think of it so far. Not saying they are bifilar or not. There is no indication so far.

Mags

picowatt

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #241 on: May 27, 2013, 04:24:42 AM »
Hey Pico

Im just stating what I read and see.  The page of the pic I posted says flat conductors. And so does the modern magnet link claim this in the repair section.

Of the 2, the pic posted seems to have 4 layers if Im interpreting the cut away view properly. And the pics of the repair coils look as to have 2 layers, like pancakes made of flat conductors and stacked ready for butter and syrup. Possibly they are in series with each other, dont know yet.  Just laying out what I think of it so far. Not saying they are bifilar or not. There is no indication so far.

Mags

Mags,

Check out the following:

http://www.jobmachineryinc.com/generator_sets.htm

http://magstargenerator.com/

If there was an easier way (i.e., more energy efficient), don't you think a tight profit margin industry like a scrap yard would be using it?

There are PM lifters available for lifting flat sheets, but for irregularly shaped scrap, big DC electromagnets rule. 

PW

Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #242 on: May 27, 2013, 04:35:14 AM »
Mags,

Check out the following:

http://www.jobmachineryinc.com/generator_sets.htm

http://magstargenerator.com/

If there was an easier way (i.e., more energy efficient), don't you think a tight profit margin industry like a scrap yard would be using it?

There are PM lifters available for lifting flat sheets, but for irregularly shaped scrap, big DC electromagnets rule. 

PW

Hmm, not gettin your drift. Im not arguing that they are DC or AC. 75% duty cycle indicates pulsed DC. Are you saying that you dont think they are wound with flat conductors?  Not sure of the point.
 ;D

Mags

picowatt

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #243 on: May 27, 2013, 04:50:58 AM »
Hmm, not gettin your drift. Im not arguing that they are DC or AC. 75% duty cycle indicates pulsed DC. Are you saying that you dont think they are wound with flat conductors?  Not sure of the point.
 ;D

Mags

Mags,

Not at all.  I fully agree that many, if not all, of these lifting magnets use flat windings.  Particularly wrt the more modern versions.

I just don't see anything that supports Synchro1's claim that the lifter depicted in the 1914 image operates on a 6 volt pulse using a capacitor that somehow causes it to remain magnetic until, I assume, a second pulse is somehow applied.

That is basically how he described the operation of that "industrial electromagnet" depicted in the 1914 image that he stated was a "Tesla Scrap Yard Magnet".

I see nothing in that 1914 image that is not consistent with a standard DC electromagnetic lifter and wondered if Synchro1 had any evidence to support his assertions, or if that was just speculation on his part.

PW 

Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #244 on: May 27, 2013, 09:01:27 AM »
Tesla also used flat conductors for ordinary transformers for obvious reasons.

http://www.google.com/patents?id=p5g_AAAAEBAJ&pg=PA2&source=gbs_selected_pages&cad=2#v=onepage&q&f=false

Page 2 lines 11 to 19.

Quote
In practice for apparatus designed for ordinary usage the coil is preferably constructed on the plan illustrated in Fig 3 In this figure LL are spools of insulating material upon  which the secondary is wound in the present case however in two sections so as to constitute really two secondaries. The primary C is a spirally wound flat strip surrounding both secondaries B.

Flat copper strips make good coil conductors in some applications. The most obvious reason to me would be the reduced resistance and increased surface area. A flat strip primary would give good coupling to a secondary winding even with not many turns itself simply because of how much of the secondary winding area the primary strip is in close proximity to. Similarly for a large spiral coil if the turns are flat strip the inductance would be more for the turns I think, because more copper is in closer proximity per turn.

Just an uneducated look at the flat strip conductors.

Happy to see the discussion heated up. I don't want to seem as though I am trying to stifle discussion, people should feel free to speak their mind, within reason.

Cheers

fritz

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #245 on: May 27, 2013, 09:37:27 AM »
Flat copper strips make good coil conductors in some applications.

Using flat foil coils is pretty standard in switched mode powersupplies.
To increase the coupling and prevent stray flux, the primary might be split in multiple parts, surrounding the secondaries.

rgds.

Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #246 on: May 27, 2013, 12:37:28 PM »
Hi Fritz, I've noticed in some appliances like televisions and such that some small HF transformers have a wide copper band around the wire windings, the copper band is soldered as a band like a shield. Wouldn't that reduce the inductance kinda like a shorted winding on a multi-strand coil ? I think I've been told it's for shielding from memory.

Anyway when I wound my second motor coil, I had to use a slightly different former with a slightly bigger core so the coil has more inductance than the other one so to keep the same DC resistance I just wound some "extra other" wire around it and soldered that extra wire "shorted" which lowers the inductance of the coil a bit. It could do with a bit more yet. It's not important though because it's just a rough test setup.

Hmmm Just thinking. 

I'm guessing that a coil wound from iron or steel wire would have lots of inductance compared to the same length of copper wire with no ferrous core.

What about aluminium wire ? Will it yield the same inductance (with a steel core) as a copper coil would for the wire length and diameter (with a steel core) or is mass a factor ?

To all:  Anyone know of a source of about 0.5 mm to 1 mm or so insulated aluminium wire for magnets ? Or even stranded thinly insulated aluminium wire ?

CHeers

synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #247 on: May 27, 2013, 03:11:44 PM »
Pancake Magnetizers are a still in use:
 
 "To test the device, we generated a magnetic field using a "PANCAKE-TYPE MAGNETIZER" and a cracked magnetized ferromagnetic specimen and imaged the vectors".
 
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6332808&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6332808

 
I came across this, I found to be very interesting about the coil's properties:

 "It is well known that the inductance of a pancake type coil put on the metallic specimen changes according to the electromagnetic properties of the metallic specimen"

synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #248 on: May 27, 2013, 03:38:30 PM »
This might help stifle the hysteria,
 
From: Electromagnetic pulse generator plans:

 "Pancake coils are perfect for the job".
 
"If you want true emp pulses, you would need to do a little research. Combining a high frequency pulsing circuit that pushing a good amount of current into pancake coils. Look up Nikola Tesla and Pancake coils to see what I mean. It is my opinion that you would not want any ferrite in any of the coils if you expect the electromagnetic field to disipate in the surrounding air either. Pancake coils are perfect for the job. Maybe a nice stack of them, and you will kick a pulse directional much stronger than firing a nail through a coil of wire with dynamite. Not to mention, you might survive when you fire it off".
 
The issue is; What are this coil's special applications? I think I've built a sufficient case so far to prove that the pancake bifilar coil's used as an "Impulse Magnetizer"!  Alright?
 
                                             " we generated a magnetic field using a "PANCAKE-TYPE MAGNETIZER"!

The question remains, how do Skycollection's ferrite toroids react when pulsed from a stack of these kinds of magnetizer pancacke coils?
 
 

fritz

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #249 on: May 27, 2013, 03:50:35 PM »
Hi Fritz, I've noticed in some appliances like televisions and such that some small HF transformers have a wide copper band around the wire windings, the copper band is soldered as a band like a shield. Wouldn't that reduce the inductance kinda like a shorted winding on a multi-strand coil ? I think I've been told it's for shielding from memory.
There are shielding layers with ferrite transducers, typicalwise between primary and secondary, foil type, with just one end connected to protective ground.
The idea behind is that in case of extreme overvoltage - the discharge should happen toward protective ground. In this case the foil is just a cap - not a single turn.

I´ve seen what you mean - I think this is used for non-flyback situations with ferrite and metal cores, reduces stray flux and works as kind of base loading to keep (iron) losses down / if no secondary load.


I'm guessing that a coil wound from iron or steel wire would have lots of inductance compared to the same length of copper wire with no ferrous core.

What about aluminium wire ? Will it yield the same inductance (with a steel core) as a copper coil would for the wire length and diameter (with a steel core) or is mass a factor ?

To all:  Anyone know of a source of about 0.5 mm to 1 mm or so insulated aluminium wire for magnets ? Or even stranded thinly insulated aluminium wire ?

CHeers
I would expect only small difference between steel, copper, al wire in terms of inductivity.
The major difference would be the resistance. Stanley Meyer uses SS resistive wire for his pulse transformers...
If you have lots of turns and thin and long wire - the resistance will give you somewhat completly different.


rgds.

synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #250 on: May 27, 2013, 08:20:36 PM »
 
This video shows a permanet magnet locking device that works by impulse shifting an alnico field. This single wire coil pulse is changing the pole around not magnetizing the alloy: Very interesting effect that in part, drives the Flynn motor  This is well worth a look!

 
http://www.youtube.com/watch?v=MZzosuvfvE4
 
Flynn gets the power of 3 magnets from 2.  A roman numeral II with an alnico and neo cylinders for cross bars, between ferrite legs completes the "Horse shoe". Imagine a monopole rotor pulsed by a micro second alnico pole switch impulse through a DPDT reed switch! This is not a "Leedskalnin" locking device. This magnet circuit field attracts from a distance. Look at the potential power savings advantage from controling a powerful permanent field with split second impulse, rather then wasting power on electrifing ampere turns.

synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #251 on: May 27, 2013, 10:10:25 PM »
Imagine an attraction motor, with a two permanent horseshoe magnet rotor mounted in opposition, and in repulsion to the 'Flynn" pulse power magnet pole polarity. The rotor horseshoes would be attracted to the ferrite legs, then a micro second pulse would release the 3x PM repulsion, and really send the rotor spinning with that little input power. We may new thread to explore this promising new build!!
 
                                                                       "THE IMPROVED FLYNN GAP ROTOR MOTOR"

                                                                   I broadened the field simply to " The improved Flynn Gap"!
« Last Edit: May 28, 2013, 12:38:06 AM by synchro1 »

Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #252 on: May 28, 2013, 12:52:08 AM »

I would expect only small difference between steel, copper, al wire in terms of inductivity.
The major difference would be the resistance. Stanley Meyer uses SS resistive wire for his pulse transformers...
If you have lots of turns and thin and long wire - the resistance will give you somewhat completly different.

rgds.

But my point is, weather right or wrong ( I don't mind which) that the steel or iron wire should act as a core as well as a wire. I mean the comparison with steel/iron to other wires when no specific core is involved (air cored coils). I am probably wrong but wouldn't a coil wound from steel or iron wire act as though it had a core of sorts (inductively speaking) even without a core piece proper. Meaning that say 100 meters of steel wire wound as an air core coil in my imagination would have more inductance than 100 meters of copper wire wound as an air core coil. I don't see why the steel/iron windings would not act as a kind of core to increase the inductance, but not as a core to concentrate flux as a regular core would. The steel wire thing is just a matter of interest I have no use in mind for that, just wondering.

Still cant find any aluminium magnet wire.   Does anyone know if aluminium magnet wire exists ? I mean thinly insulated stuff so as much wire as possible can go on a certain former. I would like to build as light a motor as possible but not a small motor and I don't want to try to use air coils I want to use cores of some kind to get good force on the rotor. I can get uninsulated aluminium wire as welding wire, but how to insulate the turns, the layers can be insulated easily enough but the individual turns per layer has me a bit stumped except for using some spacing material between turns, then a short is but a bump away kind of, shorting between two individual turns is not a great loss I guess if it was to happen it's not the end of the coil.

Cheers

TEKTRON

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #253 on: May 28, 2013, 03:22:42 AM »
But my point is, weather right or wrong ( I don't mind which) that the steel or iron wire should act as a core as well as a wire. I mean the comparison with steel/iron to other wires when no specific core is involved (air cored coils). I am probably wrong but wouldn't a coil wound from steel or iron wire act as though it had a core of sorts (inductively speaking) even without a core piece proper. Meaning that say 100 meters of steel wire wound as an air core coil in my imagination would have more inductance than 100 meters of copper wire wound as an air core coil. I don't see why the steel/iron windings would not act as a kind of core to increase the inductance, but not as a core to concentrate flux as a regular core would. The steel wire thing is just a matter of interest I have no use in mind for that, just wondering.

Still cant find any aluminium magnet wire.   Does anyone know if aluminium magnet wire exists ? I mean thinly insulated stuff so as much wire as possible can go on a certain former. I would like to build as light a motor as possible but not a small motor and I don't want to try to use air coils I want to use cores of some kind to get good force on the rotor. I can get uninsulated aluminium wire as welding wire, but how to insulate the turns, the layers can be insulated easily enough but the individual turns per layer has me a bit stumped except for using some spacing material between turns, then a short is but a bump away kind of, shorting between two individual turns is not a great loss I guess if it was to happen it's not the end of the coil.

Cheers
http://www.hmwire.com/Aluminum_Wire.html

Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #254 on: May 28, 2013, 03:24:15 AM »
But my point is, weather right or wrong ( I don't mind which) that the steel or iron wire should act as a core as well as a wire. I mean the comparison with steel/iron to other wires when no specific core is involved (air cored coils). I am probably wrong but wouldn't a coil wound from steel or iron wire act as though it had a core of sorts (inductively speaking) even without a core piece proper. Meaning that say 100 meters of steel wire wound as an air core coil in my imagination would have more inductance than 100 meters of copper wire wound as an air core coil. I don't see why the steel/iron windings would not act as a kind of core to increase the inductance, but not as a core to concentrate flux as a regular core would. The steel wire thing is just a matter of interest I have no use in mind for that, just wondering.

Still cant find any aluminium magnet wire.   Does anyone know if aluminium magnet wire exists ? I mean thinly insulated stuff so as much wire as possible can go on a certain former. I would like to build as light a motor as possible but not a small motor and I don't want to try to use air coils I want to use cores of some kind to get good force on the rotor. I can get uninsulated aluminium wire as welding wire, but how to insulate the turns, the layers can be insulated easily enough but the individual turns per layer has me a bit stumped except for using some spacing material between turns, then a short is but a bump away kind of, shorting between two individual turns is not a great loss I guess if it was to happen it's not the end of the coil.

Cheers

"Still cant find any aluminium magnet wire.   Does anyone know if aluminium magnet wire exists ? I mean thinly insulated stuff so as much wire as possible can go on a certain former."

Some speaker companies use aluminum wire for their voice coils. Ive seen flat(well rectangular) and square wire on voice coils but not round as of yet in Al. So yes it should be available. Im pretty sure Al has a higher melting point than copper and is definitely lighter so high power and less moving mass could be a motive there. If we were to pick apart the resistance value differences, for a speaker 4 ohms is 4 ohms and 16ohms is 16 ohms.   I dont believe there are any operational differences between copper and aluminum coils with equal/similar electrical properties.

Iron wire? I dont know what would happen there. If it acts as a core, then maybe most of the field produced remains in the wire/core till over saturation. I dunno. Maybe it wont saturate so easy because of a core with many gaps and voids between windings. Square wire would help but still a bit gappy. ;)

Mags