Hi Mariu
A guy named Kevin in Vancouver BC Canada ("Journey") is testing a small orbo-type motor very similar to what you are doing and he has some ferrite magnets at 90 degrees to his torroid coils, postioned at the sides of the torroids.....
here is his youtube channel with videos of it:
http://www.youtube.com/user/XoFFoX777?feature=mheehe says these magnets makes the thing really race up huge in rpms -
I think it is around 70ma draw at 12V and 3000rpm he is gettig which is pretty good performance
.he has the magnets inside a "T-shaped" PVC pipe that is positoned to the sides of the torroids...
Here is his description of his "helper magnets" setup: (taken from EVGRAY yahoo group from a few days ago message #59996)
EVGRAY discussion board link:
http://groups.yahoo.com/group/EVGRAY/here is Kevin's quote about the magnets beside the torroids;
"About the mags in the tubes ...
The ones in there right now are just plain old weak ferrite mags that
were cheap as Borscht so I grabbed a whole shit load of em. 3/4" and 1"
ferrites that I think are very low grade. So the tubes are just a
plumbing T with a 3/4" inner diameter which the 3/4" mags fit nicely in
there. Unfortunately, I can only get about 18 of those mags to fit in
there due to the other end of the T narrowing slightly. I will just have
to hone that other side out to get more mags in there. The more mags the
faster it goes. You can use just one stack on one drive coil but works
even better when using two on opposite towers. At first you have to find
out which pole of one stack makes the motor speed up. One pole will
speed it up the other will slow it down. So lets say just for example,
the north pole makes it go faster on the 1st tower, then you use the
north pole for the opposite tower. I'm not sure yet just exactly what
is going on but I do know that the inductance value of the coils changes
quit a bit when a magnet is close to the core. With the coil out of the
tower and not connected and a magnet stuck right against the coil, the L
value goes down a lot.
My ferrite cores have an Al value of 18,000 in case anyone is wondering.
The toroids inductance values are very high, 2 are at about 1.1 H and
the 3rd is 1.26 H and the 4th is 1.35 H. I also observed when they are
in circuit and the rotor is spun by hand with the inductance meter
measuring one or all coils L value changes up and down as well. Patrick
told me that this is a problem with the meter ... I'm not convinced tho.
So I have added on occasion a 3rd stack of magnets on the other open
tower #2 where there is still room and it speeds up yet some more. If my
silly pick up coil is moved I can add a 4th stack as well for more speed
I would assume. They also change the current draw. When I was using only
2 drive coils when the mags were applied the current draw would go down
quite considerably. I haven't checked lately what it's doing now that
there are 4 coils. I would imagine its the same.
Using very strong Noe mags produces a more speed but depends on the
diameter of those neos. The same 3/4" neos work better than the ferrites
but need a slightly different placement further away from the towers.
We have to realize that these fields from the external mags are
interacting with the rotor mags as well which could be adding
torque/speed. Cuz whenI use large stronger mags, you can really feel
and hear the extra energy ... it starts to vibrate and shudder, makes
more noise. So I'm sure there is an optimal field shape and strength
that works best for a given coil size and rotor mags size ... all a
balancing act."