Storing Cookies (See : http://ec.europa.eu/ipg/basics/legal/cookies/index_en.htm ) help us to bring you our services at overunity.com . If you use this website and our services you declare yourself okay with using cookies .More Infos here:
https://overunity.com/5553/privacy-policy/
If you do not agree with storing cookies, please LEAVE this website now. From the 25th of May 2018, every existing user has to accept the GDPR agreement at first login. If a user is unwilling to accept the GDPR, he should email us and request to erase his account. Many thanks for your understanding

User Menu

Custom Search

Author Topic: Tesla's "COIL FOR ELECTRO-MAGNETS".  (Read 505667 times)

Farmhand

  • Hero Member
  • *****
  • Posts: 1583
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #255 on: May 28, 2013, 04:03:08 AM »
Thanks guy's, TEKTRON I think either of the two basic lower temp coatings would suit for my intentions, preference to the 180 degree rated stuff. Much appreciated.

I'll search for other suppliers now I can see it seems common. Just hope the price is do able.

I'm not sure that many compromises can be made on the cores as far as weight goes. As far as wire is concerned then aluminium would have to be the best for lightweight performance.

Thanks again, please forgive my ignorance I should have been able to find that myself.

Cheers

Farmhand

  • Hero Member
  • *****
  • Posts: 1583
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #256 on: May 28, 2013, 04:45:37 AM »
Now that annoys me, I just spent almost a half hour filling in a quotation request form and then when I went to press the submit button nothing happened, the request can't be sent.. So now I will have to send a personal Email which probably won't be replied to because I only want 1000 feet of wire. They even want to know a business name and why I want it.

Anyone know where the prices are listed I can just order some and it will come in the post ? I can't find any places that list the price and allow direct orders of listed stock/products.

Cheers

kooler

  • Sr. Member
  • ****
  • Posts: 471
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #257 on: May 28, 2013, 05:16:35 AM »
"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."

 
Mags
the only aluminum magnet wire I have got is the degauss coil out of a crt.. it looks like copper but everyone I have torn down isn't but that may be to big for you..

Magluvin

  • Hero Member
  • *****
  • Posts: 5884
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #258 on: May 28, 2013, 05:58:20 AM »
the only aluminum magnet wire I have got is the degauss coil out of a crt.. it looks like copper but everyone I have torn down isn't but that may be to big for you..

Thanks kooler

Im not lookin, but that sounds like an in the pinch source.  ;)   

Mags

fritz

  • Sr. Member
  • ****
  • Posts: 424
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #259 on: May 28, 2013, 10:06:27 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.

I got your point - but if the windings are almost 90 degrees to your sum flux direction - there wont be an induction phenomenen in the wire - and there should be pretty no contribution to the overall inductivity.
The contribution to overall inductivity would increase if you change the inclination of your windings from 90 degrees towards 45 degrees in  relation to your sum flux / rotational axis.
As long as you don´t exceed flux saturation in your ferro magnetic wire - you will observe increased inductivity - if you saturate the wire, inductivity will fall back to normal - and there will be iron losses in the wire.

rgds.

gyulasun

  • Hero Member
  • *****
  • Posts: 4117
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #260 on: May 29, 2013, 12:44:42 AM »
Here is a cutaway view of the old scrap magnet below. And the page link here.
http://en.wikipedia.org/wiki/File:Lifting_electromagnet_cross_section.png

It says flat conductors and it looks like 4 pancakes together?

Then there is this from a link you guys provided. Its the repair page with some pics that show flat conductors.   
http://www.walkermagnet.com/service-repair-scrap-magnet-repair.htm

Mags

Hi Mags,

I found a patent on this type of electromagnet i.e. on the old scrap yard magnet. Yes, it has 4 pancake coils layered one above the other i.e. there are 4 layers (in the patent: sections) from the pancakes as the cross section drawing shows. BUT the pancake coils has no parallel conductors as per FIG 2 of the Tesla Coil for Electromagnet patent defines, they are all wound from single flat conductors and not parallel guided ones and insulating layer is interposed between the turns. And if say the first layer at the top is clockwise wound, then the next layer under it is in counterclockwise and again the 3rd layer is cw the 4th at the bottom is ccw,  so that connection could be simplified for the layers while getting like poles for all layers. This is a link to the patent US1325914, filed in 1907 and granted only in 1919): http://www.google.com/patents/US1325914
(In fact there is another patent on quasi the same construction from the same Cutler-Hammer MFG by another guy, filed in 1910 and granted in 1920: http://www.google.com/patents/US1334504 ).

This means that no series bifilar coil construction (SBC as synchro1 labels it) was used in the Cutler-Hammer scrap yard electromagnet construction. The fact that this flat pancake coil construction utilizes its both magnetic poles for lifting the scrap iron pieces makes it to be a strong electromagnet indeed (the magnetic poles can close via the lifted iron pieces, multiplying the holding force).

Gyula

PS I have attached a rough drawing as an addition to the cross section drawing to show the created magnetic poles. Notice that the pole in the center has a higher surface area than the one at the outer edge, this is intentional as described in the patent.

synchro1

  • Hero Member
  • *****
  • Posts: 4720
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #261 on: May 29, 2013, 04:06:46 AM »
Hi Mags,

I found a patent on this type of electromagnet i.e. on the old scrap yard magnet. Yes, it has 4 pancake coils layered one above the other i.e. there are 4 layers (in the patent: sections) from the pancakes as the cross section drawing shows. BUT the pancake coils has no parallel conductors as per FIG 2 of the Tesla Coil for Electromagnet patent defines, they are all wound from single flat conductors and not parallel guided ones and insulating layer is interposed between the turns. And if say the first layer at the top is clockwise wound, then the next layer under it is in counterclockwise and again the 3rd layer is cw the 4th at the bottom is ccw,  so that connection could be simplified for the layers while getting like poles for all layers. This is a link to the patent US1325914, filed in 1907 and granted only in 1919): http://www.google.com/patents/US1325914
(In fact there is another patent on quasi the same construction from the same Cutler-Hammer MFG by another guy, filed in 1910 and granted in 1920: http://www.google.com/patents/US1334504 ).

This means that no series bifilar coil construction (SBC as synchro1 labels it) was used in the Cutler-Hammer scrap yard electromagnet construction. The fact that this flat pancake coil construction utilizes its both magnetic poles for lifting the scrap iron pieces makes it to be a strong electromagnet indeed (the magnetic poles can close via the lifted iron pieces, multiplying the holding force).

Gyula

PS I have attached a rough drawing as an addition to the cross section drawing to show the created magnetic poles. Notice that the pole in the center has a higher surface area than the one at the outer edge, this is intentional as described in the patent.

Layering counterwound pancakes together cause them to share the same kind of characteristics found in the serial bifilar pancake.

Magluvin

  • Hero Member
  • *****
  • Posts: 5884
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #262 on: May 29, 2013, 04:12:04 AM »
Hi Mags,

I found a patent on this type of electromagnet i.e. on the old scrap yard magnet. Yes, it has 4 pancake coils layered one above the other i.e. there are 4 layers (in the patent: sections) from the pancakes as the cross section drawing shows. BUT the pancake coils has no parallel conductors as per FIG 2 of the Tesla Coil for Electromagnet patent defines, they are all wound from single flat conductors and not parallel guided ones and insulating layer is interposed between the turns. And if say the first layer at the top is clockwise wound, then the next layer under it is in counterclockwise and again the 3rd layer is cw the 4th at the bottom is ccw,  so that connection could be simplified for the layers while getting like poles for all layers. This is a link to the patent US1325914, filed in 1907 and granted only in 1919): http://www.google.com/patents/US1325914
(In fact there is another patent on quasi the same construction from the same Cutler-Hammer MFG by another guy, filed in 1910 and granted in 1920: http://www.google.com/patents/US1334504 ).

This means that no series bifilar coil construction (SBC as synchro1 labels it) was used in the Cutler-Hammer scrap yard electromagnet construction. The fact that this flat pancake coil construction utilizes its both magnetic poles for lifting the scrap iron pieces makes it to be a strong electromagnet indeed (the magnetic poles can close via the lifted iron pieces, multiplying the holding force).

Gyula

PS I have attached a rough drawing as an addition to the cross section drawing to show the created magnetic poles. Notice that the pole in the center has a higher surface area than the one at the outer edge, this is intentional as described in the patent.

hey Gyula

I was just showing what I found on those magnets. I hadnt stated that they were bifi or not. Didnt know. ;D

I dont know if old lock motors in cars were bifi either, but the old impala I worked on recently used large solenoids. They did all kind of weird stuff back then. Like wind 2 stator coils in window and windshield wiper motors. Naturally they were wound together, bifi, but only one was used for one direction and one for the other direction.

The stators were in series with the armature, but one stator was wired in opposite polarity. Apply power to the stator that makes the motor go in one direction or the other.  What a waste of wire.  I guess they just didint know.  Everything is so much easier with PM's. ;)


I had an idea of weirdness the other day...

Ever really look at how a voice coil functions in the speakers magnetic gap?

If you have ever put dc to a speaker terminals, the speaker cone is forced forward or backward depending on the input polarity. Well if you hold the dc on the terminals, the cone is kept in that forced position being held back by the cone suspension.
Now, if the voice coil were 10ft long or even 100 ft. and the whole thing was built for the coil to be able to move full stroke, if we applied dc, the coil would move all the way till it left the magnet gap. ;) It would keep going till the mag field was no longer affecting the coil.

Ok, here is what I propose. Some things will have to be worked out, but follow me...

We wind an air core toroid, air core for now, in a complete loop(toroid) say 2in thick and 12in outside and 10in inside diameter.  Now we make a rotor with say just 2 magnets on opposite sides of the rotor, same polarity outward, that are set to rotate within the inner diameter of the toroid coil so that the rotor magnets are in close proximity to the inner side of the toroid winding...  This I believe would emulate the 10foot long voice coil but it instead would be infinitely long, not just 10 in.

This is just and idea that popped into my head. It is only a possible proof of concept design as described. Might work with a toroid core, or maybe more core toward the outer diameter of the toroid but inner side of the windings stepped away(inward) so the field of those parts of the winding are not just trapped in the core and can affect the rotor magnets.

It is just a possible way to make a dc motor without switching what so ever. If one really understands the workings of a speaker, then it isnt hard to imagine this motor idea to work similarly, with dc input.  ;)

Just throwing it out there. ;D   So simple to implement.

Mags

Magluvin

  • Hero Member
  • *****
  • Posts: 5884
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #263 on: May 29, 2013, 04:26:08 AM »

Layering counterwound pancakes together cause them to share the same kind of characteristics found in the serial bifilar pancake.

I was thinking the same thing, but Gyula has shown another pat that seems to clearly show that the connections from coil to coil alternate one wound out, then connected to the outside of the next coil down and so on. This would mean that each cake is wound in the opposite direction of the next for the magnetic polarity to stack up. If it were that they are in series and each series connection started at the inner or outer end of each coil then yes, this would divide the voltages between adjacent upper and lower windings to be defined as a bifi. It might have a very small effect though being that only the upper and lower 'edges' of each winding are in proximity to the next level winding, being they are ribbon conductors.

Now, if you were to 'show' me that each layer were bifi with 2 conductors each, then I would agree. But I have not seen that so far.  Maybe there were some out there. But so far it doesnt seem so. Yet. ;)

Mags

synchro1

  • Hero Member
  • *****
  • Posts: 4720
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #264 on: May 29, 2013, 04:49:13 AM »
Look at this discussion:

                        "Alternatively, a three-wire coil design has two windings in opposite directions".

Latch Valve Designs

Reversing electrical polarity is accomplished in one of two ways.  A two-wire coil design has one winding and the device’s electrical source changes the polarity applied to the valve.  Alternatively, a three-wire coil design has two windings in opposite directions. Power is then selectively applied by the device’s power source to one of the windings creating a certain polarity or applied to the other winding for the reverse polarity.  Again, electrical power is applied in brief 20 to 50 millisecond pulses after which no power is applied.  Three-wire valves are more expensive than two-wire valves. Latching valves operate on DC current.  AC current can be used, but a special valve coil must also be used to convert the AC to DC current.

MileHigh

  • Hero Member
  • *****
  • Posts: 7600
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #265 on: May 29, 2013, 05:23:05 AM »
You can see when you look at the drawing that there are four layers of band-iron formed into coils that are stacked one on top of the other.  There are some nice supplementary drawings if you follow the patent links.

All four layers form a giant ampere-turn magnetic field generator that work together.  You can see how the metal casing of the electromagnet takes the "top" flux and channels it to the center and "points" it downwards.  The same "top" flux is also channeled to the outer ring of the casing and is also "pointed" downwards.  So Gyula's "magnetic footprint" drawing is wrong.   If the center circle of his drawing is red, then the outer ring that he has marked in blue is also actually red.  Following Gyula's convention where blue represents the opposite polarity, then what Gyula shows as white should be blue.  In summary, at the inside you have the red circle, then you have a blue ring around that, and on the outside you have a thin red ring.  That's how the electromagnet is designed.

In looking at the other drawings, the blue area (my definition) seems to be recessed.  That makes the recessed blue area a kind of "suction zone" for scrap metal when the electromagnet is energized.

I will repeat again, to make a connection between Tesla's patent and the two electromagnet patents shown here is nonsensical.  Talk about minuscule inter-layer capacitance in this brute force application makes no sense at all.

MileHigh

sparks

  • Hero Member
  • *****
  • Posts: 2528
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #266 on: May 29, 2013, 01:07:55 PM »
   The old magnets in junkyards have to let go of the stuff.  They used at least two windings.  Like an automotive starter solenoid.  One high current to polarize the load steel.  One low current to maintain the stuff on the magnet while it was transported.    Then when you want to drop the stuff the holding current winding is opened.  The kick voltage of the high resistance winding goes sky high so the switching devices used mercury plungers I believe and dumped the kick energy into resistor banks.  This is from memory of a brief read 30 years ago so take it for what it's worth.
  IMHO a tesla pancake coil is nothing but a piece of coiled coax.  If you take a piece of coax and hit it with RF to INCREASE the standing wave ratio  (reflected signal)  soon you develop high voltage relavent to nodes and antinodes within the coax.  If your node and antinode develop at terminals then you get what Tesla was after.  We know that electromagnetic waves carry energy so when they stand and are constructive the pancake coil acts as an energy storage unit.

gyulasun

  • Hero Member
  • *****
  • Posts: 4117
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #267 on: May 29, 2013, 03:39:34 PM »
Hi sparks,

I agree with you, in the Tesla pancake coil as defined in his Coil for Electromagnet patent, Figure 2, the two conductors (in very close proximity but still isolated from each other) constitute a transmission line just like the coax cable that also includes two isolated conductors.  Ham radio operators do use so called coax trap coils to get frequency selective switches in their antennas to have multiband operation in the short wave bands. The coax traps have many series and parallel resonances as per their impedance curve shows in the function of frequency: http://vk1od.net/antenna/coaxtrap/coaxtrap10.png  from this link: http://vk1od.net/antenna/coaxtrap/ 
It is sure that Tesla was aware of how the impedance of his two conductor coil changed when connected the two isolated conductors in series because he wrote that at resonance the input AC current finds no impedance other than the conductors resistance, this way the usual and inherent coil propety to resist initial current flow is solved. 

However, in the junkyard electromagnets (as per the two patents described in my previous post above) the pancake coils used single conductor and no any mention of using two conductors as per Tesla's  Fig.2 defined.  So what you wrote energy-wise for the coiled coax (which I agree with)  is not valid for a single conductor pancake coil.

Gyula

synchro1

  • Hero Member
  • *****
  • Posts: 4720
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #268 on: May 29, 2013, 04:06:15 PM »
   The old magnets in junkyards have to let go of the stuff.  They used at least two windings.  Like an automotive starter solenoid.  One high current to polarize the load steel.  One low current to maintain the stuff on the magnet while it was transported.    Then when you want to drop the stuff the holding current winding is opened.  The kick voltage of the high resistance winding goes sky high so the switching devices used mercury plungers I believe and dumped the kick energy into resistor banks.  This is from memory of a brief read 30 years ago so take it for what it's worth.
  IMHO a tesla pancake coil is nothing but a piece of coiled coax.  If you take a piece of coax and hit it with RF to INCREASE the standing wave ratio  (reflected signal)  soon you develop high voltage relavent to nodes and antinodes within the coax.  If your node and antinode develop at terminals then you get what Tesla was after.  We know that electromagnetic waves carry energy so when they stand and are constructive the pancake coil acts as an energy storage unit.

Thanks Sparks. The high voltage polarization you speak of is also refered to as: "Impulse Magnetization". Those old fashioned magnets are long gone. Consider what the time frame did for the field of Aviation, from Kitty Hawk to the Mars Rover. It's hard at first for us to understand the Wright brother's method of wing warping to gain directional control, even though wing flaps are commonplce today on aircraft.

The argument arose about the differences between SBC and single wire coils. Both coils are used to "Impulse Magnetize" but they work differently. The SB Pancake directs the pulse to align electron spin in a substrate while the single wire wrap coil polarizes.

gyulasun

  • Hero Member
  • *****
  • Posts: 4117
Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #269 on: May 29, 2013, 04:16:10 PM »

Layering counterwound pancakes together cause them to share the same kind of characteristics found in the serial bifilar pancake.

Sorry, it is not correct.  The facing pancake surfaces are not comparable for the two cases, that is why I disagree.  See also Magluvin answer here http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg361720/#msg361720

Gyula