Just finished testing parallel mosfets.I'm usingIRF840 wich have 0.8ohm(400V / 8A). I put 10 of them and the result was not good.The voltage droped from 150 to 60V.Just like the IRFS640 wich have 0.18 ohm.(200V / 9.8A). Maybe i must change the coil...thicker wire....i dont know.

Hi Mariu
Cant say for sure why those paralell mosfets dont work right -  one thing is the turn-off might not be like it should, since you have that crazy 100ohm resistor on one bank of mosfets and the 10K on other (I assume you are doing it like your drive coil circuit)...and you arent using a driver chip too.
I will bet you are going to eventually need to use a driver chip for paralell mosfets and to improve your system and make it reliable.......
500V rated mosfets are proabably the minimum voltage you should use.
Maybe those paralell mosfets you used are  have some internal diode that restricts them (dont know)
If you voltage drops like that I assume its a diode problem but dont know...other thing is the timing is way off, and you arent at the peak when you short...
mabye there is timing issues with so many mosfets in paralell - they are all doing their "own thing"
That pull-down resistor across the gate is very important in most any mosfet so that the internal cap quickly drains, and the mosfet turns off properly, and very quickly....when you have a lot in paralell, then what I do is each mosfet in the bunch has a 10K resistor from its gate to its source, plus there is another single 10K resistor that streches across the whole cluster too from the paralell-gates to the paralell-sources - so for sure paralell mosfets should turn off correctly this way..
The way I do pulse-width adjustment with hall effects and mosfets is to use a 4421 driver chip on one mosfet, (or cluster of paralell mosfets) and this will be normally OFF, swithces ON and this has its own halleffect too.
Then I have another mosfet (or cluster of paralell mosfets) with a 4422 driver chip, instead of the 4421....now this makes this mosfet (or cluster of paralell mosfets) become normally ON, and switches OFF, and this has its own hall effect too...(same type of hall effect as other)
Then the two mosfets (or cluster of paralell mosfets)  hook together in series...
now put the hall effects very close together, and have them drift apart or get closer....to make it easier you can have a halleffect trigger by another "in phase" trigger magnet so you dont have to have them right together....
theres no way I could do the 100% no lenz coil shorting without the super narrow pulse width...on the scope, it is just a narrow slit no real "pulse" to it...at 60hz it is .25 millisecond or less....
I made a couple directional drive coils today and instead of doing a wrap of telfon over the whole layer, instead I just wrapped the "pull back" portion of the wire that streches from the front back to the back with that teflon plumbers tape - so no "external" wires this way - its all inside, between each layer and the teflon tape prevents chaffing...with two layers of teflon tape per layer, it made the coil fairly fat looking - I wanted the layers to be  tighter, and closer to the ferrite cores....
Played with magnets behind the cores today in my Romeor variant machine - that is really amazing and makes no sense at all in how they improve the perfoormance and rpms....having the magnet behind the GENERATOR coils is super important, when pulsing with the drive coil...(why???) I just had single dirve coil on bottom plate as experiment - and ALL the generator coils on top plate need magnets behind them - but why is this? makes no sense, but it triples.quadruples the rpm with less draw ....
on bottom plate I have core-backing-magnets on only two of the 5 coils in the bottom plate...also this makes no sense whatsoever - why 5 magnets on top plate and only 2 on bottom?? seems logically there should be 5 on each coil on bottom plate too,  but if you put magnet on the other 3,  it slows badly....very strange...I've gone through the possiblities over an over it always comes out this way on this particular  machine - very strange but it really works great...I think this is the greatest "discovery" Romero made - the backing magnets and nowadays I am thinking this is why his machine looped itself too - and why he cant really explain "how" it did since the backing magnets are going to be very particluar and peculiar to each machine in how they make the rotor race up in speed.....
anyways I bet you could double your speed with same draw if you could get some backing magnets to work on those long ferrite cores - mabye ring-shaped neo magnets...this is what magnacoaster has - ring shaped neos on end of core...
I have  stack ring shaped magnets for my backing-magnets behind the cores, since I have a SS mounting-bolt jutting out the back that they slip around....sometimes it likes 3 stacked, and with some coils,  4 stacked for longer stronger magnet...that is the other variable with the backing magnets- how strong they are, and I control this with how many are stacked....
 

I think i got something here.
FINALLY i managed to charge a cap with no lenz at all . The gen coil is not affecting the rpm. i  tooked out the hall and connected a signal generator that gives pulses every 5 microseconds.This way the sine wave is shorted every time, not only at the peak. ISN'T THAT CRAZY??? The cap that i charged is 22uF and and not to fast too. 20V in 10 sec. But i'm sure that after i'll tune this circuit there wiil be much  more power out

Hi Mariu
have you seen the video of the "stargate" motor - its a conventional DC motor and he stacks neomagnets around it, and it goes super super fast (but I bet the cores get hot, besides the bearing-sleeves):
http://www.youtube.com/watch?v=5Xv-req4U8U
 
Anyways, I'll take some pictures of my romero-variant machine, with all the magnets in place - I'm not so good with videos right now...
basically now that I installed two facing coils in series for about 6.4ohms in coils resistance, the motor goes around 250-300rpm wihtout any magnets and with magnets, it now goes 960rpm which is huge difference -  only magnets doing this increase in speed!....draw to motor while it goes 960rpm is 60ma and 12V ...which is really low draw plus I have 5 coils on each plate, with ferrite cores too...Ihave only 4 magnets in rotor, going to put in 4 more for 8.....
 

Hi Gyula!
Thanks for the info on the mosfets. As i said before i'm no good with electonics;especially with details, so any info is welcome!
Still playing with coils and shorting. The gen coil in the picture produces 3V at 3500rpm.(the magnets are very weak). With this kind of shorting , voltage rises much more than i expected. I have connected to the mosfets a simple flyback driver circuit. Now lenz is here again but not so strong. Pulses are around 5 microseconds .If i could give only one short pulse per sine wave i'm conviced that we could charge caps, large caps, with allmost no lenz

Hi Khwartz

Hi Kone
 

you almost got the formula right - but at the very end of it you have f  2  - (cant make a small 2 on this keyboard like you wrote)

...but anyways it is how many discharges within one second that you times it all by at the end of the formula - you dont square the freqpencuy or anything like that jsut times it all by discharges per second..

Ok, if you say so Kone, I believe you! more seriously, you were right I was wrong indeed! I've checked the dimensional equation I didn't checked before and it fits perfectly without squaring the frequency because P [W] = 0.5 * C [F = A*T/V] * (Vmax²-Vmin²) [V²] * f [Hz = cycles per second = T^-1], when simplified gives: V * I = P

You cant measure current without resistance...if you have no resistance across a cap, then the cap fills up without current really - only resistance really is the cap itself then -
good thing is, to make anything resonate you need a cap, just like you need a violin body to resonate the vibrations of the strings...without a violin body, there would be no resonance, without a cap you cant resonate anything electically....so having a cap in system is good, filling it without any resistance is good, and when you hit aload with cap, disconnect the cap from its "source" when the cap hits load pretty simple eh - this way the "source" never sees the load.

I knew for needing of cap for resonating, but now, it's even clearer to me for what we try to do and yes, i'll remember that the load must not meet the coil at any time

I cannot  understand a single sentence that Tom Beardan writes sorry.....

hehe, it's ok! for me too, his language doesn't look to me very academic, and I'm surprised not having been able to find any true mathematical formula as any true scientist would be able to produce to make any other experimentator to replicate and even predict the results expected. but I didn't have so much read from him, ans surely with bad translations too, so... I don't know if he knew exactly what he was doing, but I think he has kind of "physicist intuition" about what's going on, that he express could be to simpler to realise he is right in his way
Did you see this vid: http://video.google.com/videoplay?docid=-988496603742502119 ?

Many pages ago, someone (i think konehead) described what happens in the coil at magnet flyby. Scope shots helped in understanding at which moment the electrons (officially ) are pushed inside the coil.
Let me recall (for a magnet travelling over a coil from left to right, magnet and coil diameter similar):
The first peak (let us assume a positive one) happens, when the right end of the magnet hits the left side of the coil windings. =>The electrons in the left windings are pushed and can travel without counterforce in the coil.
When the magnet is in the center position, the scope shows a "zero". =>The electrons in both sides of the coil are pushed in opposite directions (right and left end of the magnet pushing electrons in the coil against each other.
The second peak then happens, mirroring the first one, when the left side of the magnet pushes electrons in the right side of the coil windings.

Therefore it is a clue for me, why most of the builders use same width (diameter) for magnets and coils.

The obvious point: if the width of the magnet is smaller (lets say minimum half) than the width of the coil, you will have four instead of two peaks, because the magnet is not able to push the electrons in the coil against each other at the same time. =>double amount of electrons are pushed by changing geometry alone...

Please let me know your opinions.

Thank you,

uu