In reguards to safty-please guy's-play it safe.
Below is a picture of one of  my moderators on IAEC.
A magnet came loose,and this was at only 730RPM. He nearly lost sight in that eye,and spent many months with vision in one eye only. Although we see them as toys,they can be very dangerous.

Analyzing the efficiency of the transistor switching is not something that you normally see but it might be something for some people in the advanced group.

There are two main goals and there are trade-offs where one optimization can have a negative impact on the second optimization and vice versa.   The two optimizations are 1) to switch the transistor on and off as quickly as possible, and 2) to burn the least amount of energy through the base transistor and diode drop of the base-emitter junction in the transistor.

The reason you want to switch the transistor on and off as quickly as possible is that the transistor is burning energy through the collector-emitter junction during the switching itself.  It the transistor switches off slowly it will steal energy from the back-EMF pulse.

Let's assume that the motor is running at its high speed steady state speed.  Let's also assume that you have done a manual test of the transistor with the drive coil to determine the minimum base current to saturate the transistor relative to the resistive load of the coil.  You may or may not want to use that data.

So you have three variables to play with:  1) the number of turns in the pick-up coil which will determine the max EMF voltage, 2) the physical size and shape of the pick-up coil which will determine what the EMF waveform looks like, and 3) the value of the base resistor.  By experimenting with your scope and watching the switching carefully and also looking at the pick-up coil voltage waveform you could in theory find a maximum efficiency sweet spot for the switching at the max steady-state speed.

MileHigh

@Tinman: The Warlock's Wheel is what Jeffery Kooistra called his Marinov Siberian Coilu experiment. He was working for Gene Mallove at the time and wrote about the experiment in Infinite Energy Magazine.

Jeffery writing in Analog: 
http://www.analogsf.com/0806/altview.shtml

Ken Rauen's analysis, which I think is incomplete:
http://www.infinite-energy.com/iemagazine/issue39/deviceupdate.html

I built one in 2000, a good testbed that had vertical mercury brushes that could contact the "stator" ring from either the inner edge or the outer edge, had a self-contained power supply (2 9v batteries) and a light-actuated switch to turn the current on without perturbing anything. The ring, the armature magnets and the powersupply/brush structure were all triaxially mounted on 3 nested axles and everything could move independently. The behaviour reported by Marinov and later by Kooistra was soundly confirmed by this apparatus.  When energised with the brushes positioned on the inner edge of the "stator" ring, the ring and the inner magnet armature both rotated... in the _same direction_. Since my brushes approached the ring from below and the lead wires were parallel to the device axis, the explanation that Rauen gives for Jeffery's results does not apply to mine, although it did appear that my ps/brush support was pushed in the opposite direction.

Let this sink in a bit. The more one thinks about it the more incredible it seems. Does the device really violate Newton? Does it work by flux leakage from the central magnets, or is this flux confined and unable to interact directly with the current in the ring?

Anyway, by interrupting the current at the right time, this thing can be turned into a pulse motor, and the magnet armature and the "stator" ring will both rotate in the same direction. An optical chopping wheel and led-photodiode pair will do the trick.

My original apparatus was damaged after I demonstrated it to a room full of physicists, when some mercury splashed out and shorted the logic chip on the power supply board. We moved the lab before I could repair it, and now it is lost. I made a version without the stator ring, substituting a cleverly wound coil to simulate the current paths in the ring. I call it the Marinov Slab motor; it runs on a 9v battery and also _appears_ to violate Newton because it is unclear what is being pushed against to turn the rotor, and it also appears to have no armature back-reaction.

@TK
Is there any clear diagrams of this device?

I'll try to sketch what I built but I'm a lousy artist.

The Phipps paper has some good illustrations that should make the basic layout clear. What is amazing about the Phipps paper, with all its careful analysis, is that he seems to have missed entirely the difference between putting the brushes on the inner edge vs. the outer edge of the ring.

http://redshift.vif.com/JournalFiles/Pre2001/V05NO3PDF/v05n3phi.pdf

Let me say it again: With the brushes on the outer edge of the ring, you give it power and the ring goes one way and the magnet armature goes the other way. No problems with Newton and Lorentz.... and this is what Phipps analyzes. But..... if you put the brushes to contact the inner edge of the ring only.... the ring and the armature move in the same direction. This is so unbelievable (and kind of difficult to implement) that Phipps apparently didn't even try it.

So the setup is like this: You have a hefty copper ring. Most people who have looked at this use copper vacuum flange gaskets, these are ideal in the 5 or 6 inch size. This is your "stator" but it must be mounted so that it can rotate freely on its central axis. You also have a magnet rotor "armature" that is mounted in the center, co-axially, and also can rotate freely. Marinov said to saw a bar magnet in half lengthwise, flip one half over and glue them together, so that you have a "flux loop" so to speak , but I just used a couple of bar magnets, stuck together so that one end of the stack has N-and-S polarities and the other end the S-and-N polarities. So you have a ring, encircling the rotor and everything is able to spin around on the same axis.
Then you arrange your brushes to contact the ring at 180 degrees apart. The brushes should be adjustable so that they can either be set to contact the ring on the outside edge or the inside edge. They can't drag the ring, torque is low, so mercury or GalInStan is used. Current is high though so the brushes need some thought.  For a first build I would make the brushes and power supply stationary, not able to rotate.
So, to start, you set up with the ring with brushes at 180 degrees apart. The magnet armature is positioned so that the bar magnets are closest to the brush points. Looking down from above you could draw a straight line through the brushes and the S and N poles of the armature magnets.
Now you give it the current.
The Armature will "snap" around to the 90 degree position so that the poles are now at the midpoints of the ring, between the brushes, and will want to "lock" in this position for as long as current is applied. But while the armature is moving to that "lock" position, the ring itself will also move, either in the same direction (brushes inside edge) or in the opposite direction (brushes outside edge). Once the armature "locks" into the position at 90 degrees to the brushes, then the rotor just coasts, it is no longer being "pushed" in either direction, and the armature wants to stay put. So just before it gets to the "lock" position... you turn the current off. This enables the armature to "coast" past the lock position until it is again lined up with the brushes, and you can apply another pulse of current (in the opposite polarity? I can't recall). This will drive the armature on around to the next "lock" position and the ring will keep coasting along. Lather rinse repeat.... and you have a pulse motor that will blow people's minds altogether, guaranteed.
Requires low voltage and high current, I was using two nine-volt transistor batteries in parallel, with a mosfet switch triggered by a light sensor, but that was for the rotating power supply. For a fixed PS, try to get 10 amps into the ring per pulse at least.

For a "proof of concept" single pulse demonstrator you can do what Jeffery did: Just glue a copper ring to the top rim of a styrofoam cup (if you use clear plastic cup you can see the armature better) , suspend it upside down with a thread, over a pair of magnets sitting on the table. Usually you don't even have to mount these magnets, just stick them together edgewise and set them down on the ends so that you have your N-S pole pair up and the S-N pole pair down.  Make two little pools of mercury in depressions in the table that the ring can contact, lower the cup/ring down over the magnets until the ring contacts your brush pools, and then use wires or foil slid under the ring edge  to make the power connection to the mercury pools. A pair of strong bar magnets, cylinders with flat ends, 1 or 2 inches long by 1/2 inch diameter, would be ideal for this proof of concept test.

It is not as complicated as it sounds, until you try to explain why it works the way it does. Marinov thought it worked by interaction with the scalar A field, since in his original conception there should have been essentially no flux leakage from the split , flipped and reassembled central magnet. But it works a lot better if you allow flux leakage, so I don't buy into Marinov's explanation, and neither did he at the end of his life.

Ideal ring:
http://www.ebay.com/itm/High-Vacuum-Copper-Gaskets-4-1-2-CF-Flange-3-1-4-/300628576466?_trksid=p3284.m263&_trkparms=algo%3DSIC%26its%3DI%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%26otn%3D21%26pmod%3D300528636168%26ps%3D54

As you can probably tell, turning the single pulse demonstrator into a pulse motor with continual rotation will be a bit of a challenge and will demand a lot of creativity.

Here is my Marinov Slab. If you can imagine the coil (it is a single coil even though it looks like two) being replaced by the ring, and free to rotate around the same axle as the rotor, that's the idea.
(Bottom view, showing Hall sensor position on its adjustment "timing" disc; the magnets are the two light spots at 2 and 8 oclock in the black Delrin rotor disk. The "virtual brush" positions are at 12 and 6 oclock, where the two half-coils almost meet.)

@TK
So we need to arange the magnets to produce the field pictured below?

Ok,i think this is a combination of the"dropping a rod magnet down a copper pipe,and the homopolar motor.
If we made a homopolar motor,and placed a free wheeling copper ring around the rotating magnet on the motor,the copper ring would rotate in the same direction as the magnet.
So we send an electric current through the copper ring,and the magnetic field would be at right angles to the electric field,as are the PM's field's to that of the copper ring.
So realy,it is working just like the homopolar motor.

No, it isn't, I think. Don't forget that the ring spins in the opposite direction from the magnets if the brushes are on the outside edge, and in the same direction as the magnets if the brushes are on the inside edge.  The ring isn't spun by eddy currents from the magnets if they are both going in the same direction; also the ring coasts freely once the magnets are in the "lock" position, even while current is still applied. Eddies must exist in that case but they are too weak to affect the motion of the ring, except maybe to slow down its coasting a little bit. The ring is only propelled (by something) while the magnets are not yet in the "lock" position at 90 degrees from the brushes, even if current continues to flow.

Does anyone think that my pulse motor powered by my earth battery would be interesting enough to enter with?  I really like the idea of this competition.  I am just not sure that any of my pulse motors would be different enough to be competitive.  The earth battery angle is about the only angle that I might have.

Bill