Hi all,I have question romerouk pulled rf chokes from equipment and used the core
from the choke.Is the choke the same as sold by radio shack?Does the core fit thru the bobbin
with out either boring the bobbin or using a dremal tool to shave down the core.
If he did have to make the
 core fit which method did he use boring the bobbin or shaving the core or both.

I tried the choke from RadioShack and the bobin and it fit perfectly. I used two bobbins for this picture where I cut the ends of each bobin. CORRECTION: it is magnetic  (wrong: The core is also not magnetic which IS GREAT).

Fausto.

Yesterday I got my new coils using Litz wire. They are 0.125mm each strand, 7 strands, total diameter around 0.375mm. The wire seems perfect. I bought it from http://www.surplussales.com/Wire-Cable/LitzWire.html item "(WHS) LW-7/36" group B. It is a gigantic spool that easily I could build 500 of those little bobbins.

I did not worry about how many turns it took. I only concentrated on making all coils as close as possible to 3 ohms. They look very alike Romero's coil so I guess Romero did not measure his coil correctly (which I doubt) or he mention the wrong number or turns. There is no way one can fill those 6mm x 10mm bobbins (internal dimensions) to the edge and still be less than 2 ohms.

I also changed my shaft and bearings. Now I am using a threaded rod for the shaft where I can control the distance of the rotor from the coils with easy and more accurate. Also it is much easier to work with small bearings. I guess my 12mm rod shaft idea will be postpone for when this becomes a larger motor.

Cores are from RadioShack http://www.radioshack.com/product/index.jsp?productId=2103978. I removed the wires and cut the core in half. They fit very tight inside the bobbins. So it is good to use a drill to enlarge just a little bit the center diameter of the bobbin and all fits perfectly.

edit: I forgot to mention. Inductance is around 1.2mh.
edit 2: No core is 0.45mh with core 1.2mh. No magents.

Fausto.

Tonight I run my replication using ONLY 2 driver coils and no generator coils installed.
The first thing I noticed is that those little coils can give a nice punch to the rotor and spin it really fast.

This is just a test run. I am using Arduino Duemilanove as multi pulse driver so that I can have more control over the pulses, and timing. I am using a hall effect.

At 3 pulses, 6 volts and around 300 to 400 ma I can spin this thing to 650rpm easily. The very interesting thing is that it will start slow than current consumption will go up to around 450ma. Than as the speed increases it will drop current to 300 and continue spinning faster and faster. Almost like switching shift in a car as the car increases its speed.

Spikes on the coils are above 250 volts. There is much more to this little bobbin coil and magnets than one would think. Attaching load to the DRIVING coils will actually help a lot in speeding it even faster for a mere 20ma increase. Very interesting. Imagine when I have all the gen coils doing that?!!!

This motor is very exciting because it is not behaving at all like an SSG or window motor or Adams. There this funny "banging" sound that magnets are causing as the speed gets to the point of "needing to switch the gear" and go in higher speed where than the banging gets smoother. As the speed increases it starts the cycle again.

Sometimes the pulsating, as the rotor speeds, misses some pulses and the rotor goes finally to the next "gear" and the whole cycle repeats.

Fausto.

edit 1: one pulse, 12.5v at 300ma, 970rpm and accelerating. Load on the drive coils make no difference on current consumption.

Sounds great plengo!  Fascinating results you are getting.  Sounds like you are on the right track. 

ALL,

I want to give you some insights that I have into this dynamo that might help you understand it better. 


1)  this generator conducts current into the output capacitor in short pulses, which come from each coil in a sequential order.   At 2400 RPM there are approximately 5700 pulses per second or a 5.7 kHz frequency.  This speed is higher due to the ODD/EVEN ratio of magnets to coils, and different sets of coils and magnets come into alighnment every 5 degrees of rotor rotation.

2)  the pulses occur around the maximum induced voltage, when the voltage increases ABOVE the output capacitor voltage.   RomeroUK's dynamo produced around 15 Volts unloaded, and 12 volts when loaded with that 12 volt light bulb,  and on the graph below I drew the red lines where this corresponds on the normalized curve.   (12/15 = 0.8 )

3)  notice that the flux is ZERO at maximum voltage according to the laws of electrodynamics, and the flux in this region of current pulses is linear (I drew thicker lines in this region)

4) However, the most important thing to note is the short duration of the pulses, approximatley 0.5 ms.   Why is this important?   It's because it is a shorter duration than the TIME CONSTANT of the coils when shorted, which is calculated as:   

tau = L/R = (5 mH) / (1 ohms) = 6 ms        (approximate, I think Romero said one coil was about 1.5 mH, and doubling the turns increases it by 4 times if coupling is 1, which gives 6 mH, but I'll derate it to 5 mH as an approximation, and 1 ohm resistance as an approximation)

and we know that it takes 4 or 5 time constants for steady state to be reached, where the magnetic induction stops and the voltage drop is all due to the resistance of the coil wire.

So what this is saying is that the flux interaction is very efficient and I^2 R losses are minimized or eliminated at higher speeds.

Design Guidelines:

1) Use big coils with lots of turns, that will give higher inductance and results in longer time constants.
2) Keep the coil wire resitance low, by using thicker litz wire or even solid wire if Litz is not available.  This will also result in longer time constants.
3) Faster speed is desirable, but with higher speeds more losses occur from air friction and bearing viscosity, etc.. however, the higher speed will compensate for a shorter time constant.
4) Biasing magnets reduce hysterisis loses in the ferrites as they cycle their magnetization.

EM

P.S.   Nice work Fausto,  I'm trying to catch up, winding coils this weekend.

EMDevices,  thanks for all the analysis.  For some reason I'm not getting what you said here though regarding the capacitor voltage: "2)  the pulses occur around the maximum induced voltage, when the voltage increases ABOVE the output capacitor voltage."

What voltage is the "output capacitor voltage"?  You aren't talking about the maximum voltage rating of the cap are you?  Sorry I'm lost on exactly what this means in this case.  (P.S.  I think I understand now after seeing your post in the main Muller thread.  Still scratching my head a bit though on this   ) 
   
   Have you seen teslaalset's explanation for what is going on in this device?  (he has a separate message thread now on this) He ran a simulation with the Ansys Maxwell program and seems to have come up with some good explanations of how it works within traditional physics.  It also appears that higher RPM is not necessarily the best for this device based on Romero's statement plus several replicators have noted some better results in the area of 1200 RPM I believe. 

   I'm having some trouble with the idea that we are putting 20 amps through the wire coils also.  With the gauge suggested by Romero and in use by some replicators I would think everyone would be smoking their wires.  You are way over my head with your calcs but just from experience I know pushing 20 amps through wire that is about 27 gauge will surely burn it out fast.  I think 27 gauge is rated around 1.7 amps. 
Thanks for your help with this and good luck in your build. 

Disregard what I said about the 20 amp pulses.    I was typing my previous post late last night and forgot that there are many such pulses per second, not just one, and their frequency is  around 5.7 kHz at 2400 RPM.    RomeroUK was showing us just ONE output waveform from a particular coil he chose.   

I'll be doing new calculations soon.


[Edit]

Ok,  notice in my appended figure the superposed output waveforms for only 3 of the coils, shifted from each other in time. I only drew 3 as an example, but there are many more.  The output is not actualy a superposition of 9 of these waveforms, as they don't add like that because of the diode bridges (FWDB) for each coil, and the single output capacitor.


What I want to do now is to calculate the number of pulses per second going into the single output capacitor from all the coils firing in sequence.

To arrive at an approximate pulsing frequency, I ASSUME all coils are generator coils (2 are actualy motor coils),  and due to the 8/9 ratio,  every 5 degree turn of the rotor will bring another magnet and coil into alignment. 

So the number of coil/magnet alignments per rotation of the rotor is:   360 deg/ 5 deg = 72 alignments per rotation

(EDIT:   an interesting side note here:  If you divide the 72 alignments by 9 coils you get 8.  this means each coil participates in 8 alignments for each rotor rotation.  It also means that the virtual rotational speed of these alignments relative to the rotor is 8 times FASTER, or a virtual "gear ratio" of 1:8  )

Each alignment contributes 2 pulses into the output capacitor (from the + and - swings) so  now we have 2*72 = 144 pulses per rotation of the rotor.

At 2400 RPM we have 2400/60 = 40 rotations per second

Therefore, the pulsing frequency is  2*72*40 = 5760 Hz    or   5.7 kHz

This is the actual pulsing frequency if we would use all the 9 coils as generator coils.

Now, if we knew the actual time settings of his output waveform, then we can determine how much they overlap or don't overlap,  so I have a feeling the pulses might just occur right after each other, as we need to overlap 9 such pulses in one period, so each coil will pulse at around 1 amp but not 20 amps like I previously said.   And it's 1 amp and not 2, becasue there is a bottom pulse sequence that contributes half the power.

I hope that clearifies things.   And regarding the question of when current flows,  notice that each coils voltage needs to rise above the output capacitor voltage, in order for the coil current to flow into it.   RomeroUK showed us his light bulb operating at about 12 Volts and 2 amps,  so each waveform tops out at 12 volts, and that's when current flows, at the top of each peak, just during that short segment at the top of the peaks of the waveforms  (both top and bottom peaks)

EM



PS.   If we wanted a more accurate pulse count, taking into account the fact that two of the dynamo coils are actualy motor coils, and not participating in the generator process, we would have to subtract their missing contribution from the total pulses we calculated above as 5760 pulses.

So here's the calculations of the missing pulses:

8 alignments per rotation per coil x 2 coils = 16 alignments per rotation,  and
16 alignments x 2400 RPM/60 sec =  640 alignments per second, and since two pulses occur per alignment:
640 x 2 = 1280 missing pulses per second

therefore, the actual pulse frequency when 2 of the coils are motor coils is:

f  = 5760 - 1280 = 4480 pulses per second

LtBolo,  I agree, calculations are a lot more complex, and I'm fully aware of that, you can be sure.   That's why what I'm calculating here is often prefaced with "approximate".    So yes, the ferrites are in the presence of the magnets and get cycled magneticaly back and forth, and their B-H curve is non-linear.   But how saturated the ferrites get, I'm not sure, since the biasing magnets counteract the moving magnets, so yes, the whole motor is quite complex, but not beyond the modeling capabilities of advanced software like teslaalset is using.  You might think these calculations are useless stuff, but us engineers live and breathe calculations every day.  I just happen to be an open minded type of electrical engineer (EE) that belives we don't know everything there is to know.   

I also agree that experimentation is key, but consider the fact that current theory is nothing more than the sum of the knowledge and wisdom extracted from lots of past experiments, and quite valuable !  Any new experiments that challenge the established theory should be scrutinized to see why?  And when the why is answered, new exceptions to the rule will be discovered and the theory revised.  Science in progress !   

So, I'm just calculating the simpler things first, because it helps me to have more insight into this motor.   

EM