The Ossie motor

[woopy]

Hi Gyula

as expected this was an interesting  weekend

Thanks to you i could try a lot of things

And especially the pancake coil. With a really exploding result as i tried to decrease the the gap to better fit the thin pancake and sunddenly the powerfull magnet attract together and the sandwitch (much too weak) collapsed and the rotor simply broke in several parts and died there.

So i decided to go on  with a weaker rotor and ferromagnetic junction between the magnets

But i can not yet evaluate the results for the pancake coil . It works but not so good and draws a lot of miliamps, and the fet get warm , but not the coil?

Than i made some test with different Pancake coils to verify the BEP theory of radial flux , but no success    perhaps my coils are too crude, but my compass did not shows any radial polarity as Bep seems to get

And finally i reinstalled my coil from yesterday with tesla connection and it fits very precisely the new rotor and it is very powerfull. Will make further test

ok thats all for today

regards

Laurent

[gyulasun]

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

[Magluvin]

Woopy
I have to say that those coils are just too little wire and too low of a resistance. make your coil thick. I am going to post a vid and you decide. If you do as I say you will have some big coils in there in a heartbeat. The back emf off of them will be enough to run a whole other motor very well without any more draw from the original battery, Or just send the bemf back to the batt as always.
But those skimpy coils aint gunna do it.  My coils in this vid are in parallel and measure .45ohm tot. But you can do series if you like, try it both ways.

you may have to make the rotor more sturdy as you will see. =]

http://www.youtube.com/watch?v=b7PR8JEVp7A

mags

[Magluvin]

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

[Jimboot]

Hey Woop, Luvyaworkmate. Been off the grid the last 3 days doing this. Trying to catch up on everyone's work. Sitting back at my bench now.