STEORN DEMO LIVE & STREAM in Dublin, December 15th, 10 AM

[lumen]

http://www.youtube.com/watch?v=veoRZh0GTkQ

Cancelling CEMF? Not sure the motor would run if the coil is between N-S magnets

This is interesting but understandable. Probably wound the coils with several layers all in the same direction.
The same results as a few loops of wire would produce.

[exnihiloest]

exnihiloest.... where a A do you see any interaction here ??!!!!!!!!

Where is your data? A model depends on what you put in.
Where is your analysis? FEMM gives the saturation only along the field lines.

Here is real life, not a simulation:

- a generator provides a 10 Khz sin signal to a toroid coil with a 100 ohm resistance in series in the circuit.
- the oscilloscope measures the voltage across the coil.
- if the core is saturated, the coil inductance is lower thus the voltage too.

1th test) no magnet: voltage reading is 4 v pp.
2nd test) coil tightly sandwiched between two magnet stacks, providing a rather uniform and transverse field through the core: voltage is 3.6v pp, near the same.
3rd test) magnets providing a field in the same plane as the toroid. Thus along some parts of the toroid, magnet and coil fields are colinear: voltage is 1 v pp.

It is to be highlighted that in the 3rd case, the two magnet stacks are farther from one another than in the second, providing a mean magnetic field in the toroid lower than in the second case and nevertheless the effect is much more important.

It is obvious that the saturating field must be in the direction where we want an effect to occur. The field from the magnet being neither toroidal nor uniform, magnetic flux cannot be confined in the core, thus coil and magnet act on one another, with emf and Lenz's law applying.

[Bruce_TPU]

Opps, my mistake. In a recent post I suggested that Steorn is using Bonded NdFeB magnets, but that was wrong on my part. I forgot that Steorn's magnet gauss measurements was on an open faced magnet that was not between two magnets, and therefore the field will be half the value.

So, 500mT is normal for a strong sintered NdFeB magnet during open faced measurements. It seems that Steorn is using either SmCo or NdFeB sintered magnets.

Hi Paul,

I was able to find  some 1" OD disc magnets here: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=469-1000-ND 

They are rated at 10800 Gauss.  10000 Gauss = 1 T.  So 10800 Gauss gives us 1.08 T.  I think that should work fine, would you agree? 

Thanks!

Bruce

[Staffman]

Naudin just posted another video... He shows how to cancel back EMF. Very cool!!! Sorry if this has been previously posted.

http://www.youtube.com/watch?v=veoRZh0GTkQ

Edit: I see it has been posted... sorry guys!!!

[teslaalset]

Ok guys, I've made an attempt to visualize what the magnitization cycle could be as I understand it right now.

The idea is that the coil is mostly at a remanent magnetic status while rotating.
Only shortly after the magnet passes the coil some action is changing the core status.

Let me know whether you agree with this.

[update]
Rotor is moving clockwise
Only in situation 3 the permeability is at maximum value at a very short time.