The Ossie motor

[gyulasun]

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I'm not sure that the sandwich type is better. The outer coil is too far from the magnets. Check this out: http://www.magneticsolutions.com.au/cgi-bin/flux-graphs?page=fluxgraphs
On that graph you can see magnetic flux, and how it decreases by increasing the distance.
The sandwich type is just a longer coil, but it has an air gape between the 2 coils it is made of. If the sandwich type has a better geometrical rate, it can be stronger, I guess.

Returning to my previous problem:
- Gyula, I guess you were right about the smaller ID, but this means when you calculate the force between the magnet and the coil, the 'A' is not the ID, but the OD. But why? I always belived that the effective area of a coil is the inner area, not area of the coil itself. Maybe I was wrong.

- Calculating B, I got that the Green coil should be about twice as strong as the Blue. But, when I tested them by connecting them is series, the result showed me that the Blue coil is stronger then the Green. So I guess, there must be some sort if geometrical rate, when the calculated 'B' is correct. The length of the wire in the 2 coils is almost the same.

- Next I'm going to make a new coil, with a much smaller ID (about 5mm), using the same geometrical rate as the Blue has: (OD-ID)/2 = l
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Hi Augen,

Ok on your 4 thinner coils you did not mean to sandwich but use them separately with 4 magnets, I do think it is BETTER than sandwiching them.

However, the sandwich arrangement also has merits especially if the coils are very narrow indeed, so that the mechanical length or thichness of the sandwiched coils are kept at a minimum possible. And the minimum possible length is attained if you use a single wire thickness coil for the sandwich layers, the case for the pancake coils. Please read in the Abstract part of this paper for explanation: ..."the turns of the coils are not concentrated at the circumferences but distributed across the diameters."  i.e. the turns of the two (or more) coils can directly and very closely face each other in the total area embedded within the circumference, so the (magnetic) coupling improves between the coils.
This explains why the small ID is needed: you have to fill the inside space with wire radially up and up, increasing the circumference;  in a conventional solenoid coil (or in a multilayer coil with high ID) there is wire only at or near to the circumference, mainly length-wise, and the inner radial-wise space is 'empty'.
Here is the paper:
http://www.ece.uvic.ca/~btill/papers/neurimp/Zierhofer_Hochmair_1996_00503178.pdf

Now back to your 4 separate coils because I also think they will be more promising.    I would like to draw your attention on an experiment Ian showed with a pulse motor, using only one big coil and he compared it to a pulse motor with 8 coils, using the same input power like the one coil motor:

http://www.overunity.com/index.php/topic,1754.msg31932.html#msg31932

(It is worth reading his further posts in the second page of the above link, though not reported ou.)

You have built a nice setup from Lego parts for sure, not to mention your coils.    I think your blue coil is 'stronger' because (even though it has higher ID than the green coil) it fits much better to your magnet cross section area than the huge green one,  this latter 'wastes' its bigger area: if you had magnets with comparable diameter to the green coil (and suppose these magnets would have the same strength than your present magnets), then I think you would have experienced the green coil was better.  I already described in previous posts above what ratio I think may be good for the coil/magnet diameter but of course the tests are to decide.

Re on the geometry of your coil, (OD-ID)/2 = l,   is it the Brooks coil geometry?  IF yes you may have to change a little that ratio to be able to reduce the length of the coils, no?

So I think the bottom line is the more coils and magnets you use in such setups, the better torque you get and if you combine this with Ossie's switching circuits to utilize the collapsing fields energy at the switchoffs, then you can have even better performance.  Will it be ou? I do not know unfortunately, I hope.  Maybe Ossie already knows? 

rgds, Gyula

[Jimboot]

I forgot about my setup.

Aaaahaaa! You wouldnt live near Narre Warren wd u?!

[Jimboot]

running 7 days non stop at 460rpm. Voltage drop hard to measure. Tried diff meters but is irregular. May have dropped .01 Time to switch & try more Augen & Gyula ideas.

[Augen]

Hi Gyula,

Maybe you are right about the coupling of the coil, but in that case you have to use them differently. For example place 2 coils about 2 cm apart so the B field is almost constant between them, and the magnet is moving between the 2 coils in a strong B field. See pic1.

I'm going to make a new coil: ID=5mm; OD=30mm; length=5-8mm. I'm hoping this will be much stronger, then the blue one (See Reply #548).

I think, using more coils will help me to get closer to OU. More coils use less energy (more coils -> higher resistance), and I'm hoping that the performance of the motor won't decrease much. (1 strong coil <-> more weaker coils, because of the less current, using the same voltage). But using more coils, you can generate more current, while using less current. (Ossie motor v1.2) I'm wondering weather the latest Ossie motor really works (12 magnets - 12 coils and 12V batteries).


Hi Jimboot,

I'm sorry, no. I'm from Europe.

Maybe we should try to build the latest Ossie motor (12 magnets - 12 coils and 12V batteries). He sad he'd got great results and achieved OU. (If I remember correctly)

[gyulasun]

Hi Augen,

Well, I think the 2cm distance between the coils would be too long, maybe 6-7mm would give much better flux strength in the gap and a 5mm thick strong magnet could still pass easily in the gap.
Re. on the more coils use less energy, this is ok and have you read Ian's suggestion on connecting series coils groups also in parallel with each other?
here it is:
http://www.overunity.com/index.php?topic=1754.msg35080#msg35080

It seems the more magnets you bring in to interact with the coils, the more flux quantity would be involved for the same input power.

rgds,  Gyula