Hi Laurent,

Sorry to hear your rotor's broken down, you ought to have used nonmagnetic spacers between the sandwich plates to counter the tremendous attract forces. You may still use such spacers later.

The higher current draw with your pancakes comes from the fact that so far you have used multiturn coils with 8-10 Ohm copper resistances and maybe higher and in series but these pancakes has (by sight) much less than 1 Ohm, this is the reason. Try to make pancakes with more turns if you have the time and patience. The MOSFET switch dissipates much more power now due to the lack of coil resistances: battery voltage is divided by the ratio of resistors, the resistors being the drain-source ON resistance and the coil copper wires. So far your coils took much higher part of the battery voltage, now this is true for the FET. You may consider reducing battery voltage too.

Here is another link on the polarity tests of pancakes:
http://www.tesla-coil-builder.com/rmfd_experiment.htm 

Remember that you have a much less diameter pancake than the video and other links show and thus it is more difficult to probe flux fields. A small flux probe made form a dedicated Hall sensor may show more precisely the fields. (Not Hall switch what you use now but Hall sensor that gives out a proportionally  changing DC voltage as the flux changes.)

Thanks for your infos.

rgds, Gyula

Also , the 5 ohm 5w resistor is a load that Im running the back emf into from the coils. this was a continuation of vids before it that explained that. =]

Mags

Hi all


Made some mosfet try with different pull up resistors and of course different results    seems that the Buz 11 is more easy to use , than the IRF 450.

But now i have to decide for a scaling up  and probably i will make a mix with very thin but 3 or 4 layers heavy copper wire (1 mm ) so i can draw much current  and very thin air gap with  more  coils probaly by pairs in serie.

I mean i plan to  make at first   4 separated power circuits for 4 pairs of coils in serie. So i can increase or decrease the power of the motor by simply adding more or less circuit in work. and no need of complex electronic . so you have  a 4 gears. And as i have noticed that  those pulse motor do not accelerate as crazy i think a 4 gears motor could be a basis for a usefull and very simple set up. ?

>So a concept with    big diameter     slow rotating   sandwitch  with Attraction simultaneous with repulsion  pulsed rotor     seems to be a good candidate.

And of course if we can get or store some flyback energy, it will be great and better and if perhaps the silmultaneous attraction and repulsion pulse could diminish the Lenz effect  ,    perhaps ?

But without testing   no results  so lets go

good luck at all and thanks for bringing your feedback



by the way Jb,  be carefull of flybackgreatwhitesharksenergy   hehe !


laurent

Thanks Jim 
The rotor is made from 1/2 in pvc board. Light, rigid and easy to work with. The bearing is from a HD. This rotor has been many motors. It started of as a Whipmag version I called the Robowhip.  I use the PVC for everything that does not need to be heavy. Comes in 1/8 to a couple in. thick in 4x8 sheet or to a cut length sold by the foot.
Depending on where you are, price is a different thing. Here it is a bit less than plexi. But its lighter and easier to work with. Comes in black and gray also. Bonds with resin and superglue. And with super glue, the bond is stronger than the material itself. I buy superglue in 2oz bottles from the hobby shop. Sanding is a breeze and no floating dust. its one of my favorite materials. I even make subwoofer enclosures with it for cars. With inner support frame to stop large area flex. Its more expensive than wood, but better tech advantages.

At the time of the vid you liked, I was only concerned with how much rotor action I could get from THIS set of batteries. I started in the out beginning with tick tick tick at 120 rpms. but what is that. All in all we need to figure out how to get powerful motors more efficient, not reinvent huge clock mechanisms. Sound good?  =]

Look at some brushless motor designs on the internet. I suddenly feel small. These guys are already approaching 100% eff  especially no load.  That is our starting point. We are working with no loads. It tells us nothing. It gives us nothing.  One thing we have to remember. In order to see or get a gain of 1 type of energy, it must be converted to another form and reconverted back to the original form. Our advantages need to take place in the conversions.
In these awesome setups you all have going, speed will be of the essence. Speed is power. Throw a pebble at me and i will laugh, shoot a bullet at at me and I will die. How much energy would be spent throwing the pebble all your might as compared to the fizzle in the shell pushing the bullet?  Well to extract the first half of that data would be a myth busters project, and I cant say they  wouldnt have trouble with that. Ive seen where they couldt have done better. We all have.   Here is the problem, using the human body to throw the pebble as fast as we can, energy needs to be spent getting the body to move also. You can work on the best, most eff way to move the body in a way to get the pebble to go as fast as you can. O now when we see the demonstration of it, by 5 different examples, how much energy total can you imagine being expelled into that throw, or flick, as a whole. Flick is something to think about here in the comparison and would hold substance in the analogy.. Some just may be able to flick the pebble faster than any throw. Maybe. Now the flick is getting closer to being the gun shot than the throw. I said closer, not close.  =]

So tighten these things up and get some speed going, then work on how to keep it or even make it faster, by using less power. Using Mosfets is ok. Just because they cannot dump as much current as a reed, well this just means you are using less input. No losses there, its less resistance than  the resistor you put in there isnt it?  But the reeds do provide impact, impulses.
Imagine if You had 10 different sets of coils to try. from small to big, deep and wide, 1 set is going to shine. Imagine 30 sets. 1 will shine.   Results from 1 random choice of base components will hold you at that level of the game. 
Its expensive to experiment ideally.
But these are just my thoughts and Im always glad to help and share. That is what this place is all about.


Think gun shot, Think dc impulse.  My bullets are small, but I have 16 of them. Machine gun. =]

Mags

Thanks Mags,
That further helps my understanding. I have so many ideas bouncing around now for improved rotor design etc it's hard to know sometimes what to focus on. Your explanation helps me to sift some of my ideas.

@futuristic this was posted on the Yahoo EVGRAY list
"cooling fan motors usually have permanet magnets in them, and you can feel
the notchy rotation to them as the cores in there line up with the magnets so there is some loss using a cooling fan motor as a chasssis unless that is differnt type of cooling
fman motor with no permanent magnet in there.

Also known as cogging. Losses can decrease with higher
RPM's.

Working on the gen still. This is the coil, battery & LEDs out of a rechargable torch. Not sure what value the battery is. I'm hoping the action of the rotor mags will charge it.