Quote from: Magluvin on May 26, 2013, 09:35:34 PM
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.

Quote from: gyulasun on May 28, 2013, 06:44:42 PM
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.

Quote from: gyulasun on May 28, 2013, 06:44:42 PM
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.

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.    So simple to implement.

Mags

Quote from: synchro1 on May 28, 2013, 10:06:46 PM

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

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.