Why does electromagnetic induction happen?

[forest]

Is it this one? 

See photo below...and http://www.google.com/patents/about?id=VMtxAAAAEBAJ&dq=390721+1888+nikola+tesla

Could be, but I rather thought about this one : http://www.google.com/patents?id=MvdbAAAAEBAJ&pg=PA1&dq=Nikola+Tesla+unipolar&source=gbs_selected_pages&cad=2#v=onepage&q=Nikola%20Tesla%20unipolar&f=false

[gravityblock]

Excellent post Goat, and it is the key to understanding the HPG!

When you have both the disc and external circuit (EC) rotate together, the emf or electric field on the disc is driving the electrons from the axis to the rim.  It is also driving the electrons in the EC to flow from the axis to the rim, where they cancel each other out.  In this case, the EC is part of the disc and there is only one emf force present in the system, so an electric field is present, but no voltage can be brought out of the system.

When there is relative motion between the disc and EC, there is an emf or electric field which drives the electrons from the axis to the rim on the disc, and another emf which is opposite in direction or polarity from the rim to the axis in the EC.  Let's say the disc is rotating clockwise and the EC is stationary.  From the disc's frame of reference, the disc is moving clockwise to the EC.  From the EC's frame of reference, the disc is moving counter clockwise.  It is the relative motion between the disc and EC which provides two opposite emf's or two different electric fields with opposite polarity to cause current to flow.  The electromotive force is the electric field, but it takes two electric fields with opposite polarities or direction to have a closed circuit before current can flow.

Changing the direction of rotation of the disc or EC will change the polarity of the system.  Reversing the magnetic field will change the polarity of the system.

When you have a disc on both sides of a magnet all rotating together on the same axle, one disc will be facing the magnet's north pole and the other disc will be facing the magnet's south pole.  Since each disc is looking at a different pole, this should change the polarity of the electric fields in the discs to be different.  This is only partially correct.  There is also a change in the direction of rotation between each disc and the magnet.  One disc will say it is rotating CW when looking at the magnet, and the other disc will say it is rotating CCW when looking at the magnet, so this changes the polarity of the system again.  Now the discs have the same polarity in electric fields.  This means if the current is flowing from the axis to the rim in one disc, then it will also be flowing from the axis to the rim in the other disc.

Place a magnet and disc on each end of the axle where the discs are facing outwards.  I'm attaching a sketch to illustrate this better.  Also the south poles on the magnets will be facing outwards.  There will need to be enough space between the magnets where there magnetic fields don't reach other.  In this setup the current should flow from the axis to the rim on one disc and then should flow from the rim to the axis on the other disc.

When we connect a wire from rim to rim on each disc, this will allow current to flow from the axis to the rim in Disc A, then will flow from the rim of Disc A to the rim of Disc B, then from the rim to the axis in Disc B.  Now we need a wire to connect the axis to the axis on each disc, so the current can then flow from the axis of Disc B to the axis of Disc A, and this will be our return path that is needed to close the circuit for current to flow.

The best case scenario for this method is to have the wire connecting the rims together to rotate with the discs and to have slip rings on the axis.  If this doesn't work, then we will need to have slip rings on the axis of each disc and to have stationary brushes connecting the rims together.  What we're doing is to have relative motion not between the disc and EC as in a conventional disc, but to have relative motion between the discs.  This will increase the voltage in the system.  It may be possible to stack and connect the discs in multiple layers to increase the voltage in the system with little to no additional energy input requirements.

I think this is one of many circuits which may lead to a self-excited dynamo that you refer to.  I believe it is possible to have a self-excited dynamo, but my suggested method may fall short.  Relativity and different frames of references is the engine behind the HPG, and is the key to unlocking the mystery.  It's all about relative motion in the system, and this is true in regular induction also!


Take care,

GB

[forest]

Kromley generator is something very similar :

http://www.google.com/patents?id=RjZsAAAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q=&f=false

[gravityblock]

When a rotor magnet moving CW approaches a stator coil, half of the coil's length will have a polarity that is opposite to the other half.  Why is that?

One end of the coil is facing towards the magnet while the other end of the coil is facing away from the magnet.  The end of the coil facing the magnet will say the magnetic field is coming from the right while the other end of the coil will say the magnetic field is coming from the left.  So, this allows two electric fields with different polarities in the system to be created in the middle of the coil.  The two electric fields are created due to the relative motion between the magnetic field and the ends of the coil.

When the rotor magnet begins to pass the stator coil, then the end of the coil facing the magnet will say the magnetic field is moving to the left while the other end will say the magnetic field is moving to the right.  This will flip the polarities of the two electric fields and the direction of the current, thus AC. 

The HPG produces a DC current because the relative motion is not changing in the system.  Whereas, in regular induction the relative motion is changing in the system between the ends of the coil as the magnet approaches and leaves.

Why does electromagnetic induction happen?  Short answer is relative motion in the system.  It's all about relative motion! 

[Goat]

Thanks for the information forest & gravityblock a lot of good information to absorb!