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Luciano
Average Member



212 Posts

Posted - November 26 2013 :  22:46:35  Show Profile Send Luciano a Private Message  Reply with Quote
Thank you ron.. this does help a lot

to 5): well that I figured.. I did remove the "anti cogging" magnets when i was in NSNS mode... I suppose its the lack of those magnets and their effect on a NNNN rotor that made me surprised of the cogging that was nearly absent on the NNNN rotor.
I will now test a modified stator, so for 8 magnets there would not be 8 coils but only 7 coils..
never more than 1 magnet aligned with a core (like in a muller-romero setup).

to 2): I understand it becoming unbalanced (I also observed different outputs with different efficiency when applying different loads) ;
do you think it would be possible to tune it for a fixed load.. (like always loading a certain supercap bank or a certain battery)?

Luc
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ron_o
Moderator



United Kingdom
1052 Posts

Posted - November 27 2013 :  17:59:12  Show Profile Send ron_o a Private Message  Reply with Quote
Hi Luc

The properties of the core material are very important , you need a material that is easily magnetized and just as easily demagnetized. Ferrite or metglas would be a good choice BUT you need to watch it's effect on the overall inductance of the coil.

The modified stator is a good idea.

Tune to fixed load.....

The answer is "yes" BUT the impedance of the parasitic load would have to be very high ( so high in fact that the available energy would be not much use )

A capacitor cannot be used as a fixed load due to fact that a capacitor does not charge in a linear fashion.

ron
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sucahyo
Average Member



Indonesia
246 Posts

Posted - November 27 2013 :  22:25:19  Show Profile  Visit sucahyo's Homepage Send sucahyo a Private Message  Reply with Quote
What can change coil's saturation?

I notice that many radiant / bedini charger circuit seems inefficient because the coil power stay on too long. But how long is too long? I read saturation is around 5ms?

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Luciano
Average Member



212 Posts

Posted - November 28 2013 :  08:34:36  Show Profile Send Luciano a Private Message  Reply with Quote
thanks ron
going to the shop now to get some plexi to make the new stators..

Luc
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ron_o
Moderator



United Kingdom
1052 Posts

Posted - November 28 2013 :  17:38:06  Show Profile Send ron_o a Private Message  Reply with Quote
Saturation is normally associated with the core material rather than the coil windings.

Different types of material ( ferrite , metglas , soft iron , silicon steel etc ) all have saturation values

Ferrite is approx 0.3 Tesla , metglas approx 1.5 Tesla

The time required to reach saturation for a given core material is given by the flux density.

I will get back with some example calculations.....

ron
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sucahyo
Average Member



Indonesia
246 Posts

Posted - November 28 2013 :  21:15:21  Show Profile  Visit sucahyo's Homepage Send sucahyo a Private Message  Reply with Quote
Thank you. I really appreaciate it. Harold Apsden suggest that coil On and off should be within saturation zone

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ron_o
Moderator



United Kingdom
1052 Posts

Posted - December 01 2013 :  18:19:30  Show Profile Send ron_o a Private Message  Reply with Quote
Sorry for the delay , i have been searching through my old notebooks but so far to no avail. so rather than keep you waiting.....

Please note that this is being written in the style of "learning about inductors" so that it is ( hopefully ) useful for all.

1) Magnetomotive force (m.m.f) = current flowing in the coil x number of coil turns

also written as F = I x N ampere-turns

Example... a coil of 250 turns with a current of 2 amps gives an m.m.f of 500 Ampere-turns

The length of the coil winding along the former now leads us to .....

2) Magnetic field strength ( H ).... this is the distribution of the m.m.f along the former

magnetic field strength ( H ) = m.m.f / length of winding along former

continuing with the example above of 500 Ampere-turns . If the former length was 10 cm ( 0.1 metres )

magnetic field strength ( H ) = 500 / 0.1 = 5000 Ampere-turns per metre

and likewise if the former was reduced to 5 cm ( 0.05 metres ) 500 / .05 = 10000 Ampere-turns per metre

This now leads us onto Permeability and Flux Density

3) Flux Density ( B ) measured in Tesla's

B = u x H
where " u " is the absolute permeability and is given as u = Uo x Ur
Uo = 4 Pi x 10 -7 for air and Ur = relative permeability of the given material ( Ur = 1 for air )

If we consider an air cored coil, using the data from above ( 10 cm former length )we get

B = 4 Pi x 10 -7 x 1 x 5000 = 0.006283 Tesla

But now if we introduce a core material into our coil ( assume Ur = 200 )

B = 4 Pi x 10 -7 x 200 x 5000 = 1.2566 Tesla

From this we can see that a suitable core material can concentrate the flux density.

-----------------------------------------------------------------------------------

Core Saturation....

1) There is no point in wasting energy trying to take a core material above it's saturation level value ( coil just get's hot )

2) choice of core material governs saturation level

3) how long does it take for a given drive coil to saturate the core material ?

Looks like we finally got to the question !

3.1 ) a coil is an inductor who's value of inductance is determined by several factors
namely... number of turns , core material (if any ) , physical dimensions

3.2 ) when a voltage is applied across an inductor the inductor instantly has the full voltage across it , however the inductor resists the flow of current trying to flow through it .

3.3 ) the time it takes for the full current to flow through the inductor is defined as taking a period of 5 time-constants. One time constant = Inductance / Resistance

At the completion of one time constant approx 63.2% of the total maximum current available is flowing through the coil

note .... the total maximum current = supply voltage / total circuit resistance

We have now introduced coil supply voltage , inductance and coil dc circuit resistance into the search for coil saturation time

to be continued

ron






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sucahyo
Average Member



Indonesia
246 Posts

Posted - December 01 2013 :  20:58:31  Show Profile  Visit sucahyo's Homepage Send sucahyo a Private Message  Reply with Quote
Thank you. That information is really helpfull.

Do you know how much ampere a coil can produce after the power is turned off, when the magnetic force is converted back to electricity?

Can we convert Tesla to watt? I mean how many electricity watt from 1 Tesla in selenoid. The stored watt is proportional to magnetic field force right?

I ask because I found 1N4007 seems inadequate for 12V system.

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Edited by - sucahyo on December 01 2013 21:06:43
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ron_o
Moderator



United Kingdom
1052 Posts

Posted - December 03 2013 :  16:49:22  Show Profile Send ron_o a Private Message  Reply with Quote
Core Saturation Part 2

The time constant ( t ) = Inductance / Resistance

As previously stated , after a period of one time constant the current flow in the inductor is at approx 63.2 % of the final maximum current.

So if we want a specific current to flow at the completion of one time constant it is necessary to calculate the final maximum current.

I(max) = I(coil) x 100 / 63.2

Example

Lets assume that a current of 1 amp is required at completion of first time constant

I(max) = 1 x 100 / 63.2 = 1.5822 amps

We will also assume that a 12 volt DC supply will be used

So , from Ohms Law the required resistance is given by 12 volts / 1.5822 amps = 7.584 ohms

A value of 5 milliseconds ( 0.005 seconds ) was quoted as a maximum core saturation time

So if we rearrange the time constant equation to make Inductance the subject of the equation
we get....

L = time constant x coil resistance ( Henry's )

L = 0.005 seconds x 7.584 ohms = 0.0379 Henry's ( 37.9 mH )

-------------------------------------------------------
@ Sucahyo

The power stored in the magnetic field of the inductor will always be less than the energy used to store it there ( main loss due to heat generated in coil , I^2 x coil resistance )

Tesla to Watts .... not directly , due to various losses ( will sort an approx eqn out )

ron
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sucahyo
Average Member



Indonesia
246 Posts

Posted - December 03 2013 :  20:10:02  Show Profile  Visit sucahyo's Homepage Send sucahyo a Private Message  Reply with Quote
Thank you.

What is the purpose of this second part? I am confuse?

Is there relation between saturation and heat? Or only from current?

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ron_o
Moderator



United Kingdom
1052 Posts

Posted - December 04 2013 :  03:53:36  Show Profile Send ron_o a Private Message  Reply with Quote
Hi Sucahyo
A coil , wound to the specifications above will produce
a flux density of approx one Tesla.
This will prevent the core saturation problem
that you asked about.
ron
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sucahyo
Average Member



Indonesia
246 Posts

Posted - December 04 2013 :  04:19:16  Show Profile  Visit sucahyo's Homepage Send sucahyo a Private Message  Reply with Quote
I see. I get it now. Thank you very much.

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Luciano
Average Member



212 Posts

Posted - April 13 2014 :  17:20:23  Show Profile Send Luciano a Private Message  Reply with Quote
I should know better than asking this question, because I have the feeling i know the answer.. but still I am not sure.
Some of you might remember Mr. caribean roots.. he used to be around this forum.
I have been following some of his coil experiments but I have been wondering about the following
he uses relatively small rotors with magnets very close one to each other.
but he does get pretty good results with his coils
the magnets are like half a magnet width away from the next magnet.

Anyway the next magnet is bound to influence the coil because it can only start exciting the coil before the first magnet has left the coil completely...

I was always told: make sure the magnets are about 2 diameters away from each other, so that the first magnet has left the coil completely before the second starts going over it.

now by having the magnets closer to each other you get more magnets for the rotor diameter and thus a higher frequency.



Here at 0:42 of this video you can see the rotor mr. caribean roots is using.. and it seems he even gets acceleration under load. (I think its on video 19 where he got it)

But anyway my question: should i build my next rotor with magnet that close one to each other (and the coils being as small diameter as his compared to the magnets) or should I stick to bigger diameter coils and bigger spaces between the magnets?
usually i do distance about 2.5 times the diameter of the magnet vs 0.5 times here.

Luc

Edited by - Luciano on April 13 2014 17:25:13
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ron_o
Moderator



United Kingdom
1052 Posts

Posted - April 14 2014 :  16:27:57  Show Profile Send ron_o a Private Message  Reply with Quote
Hi Luciano

The video shows the coil being used purely as a generator coil so its performance is governed by Faraday's Law.

If the coil were being used to power a pulse motor then a new set of rules apply ... namely the requirement for the coil to have sufficient time to turn on and off so as to provide maximum repulsion between itself and the magnet on the rotor.

Since an inductor ( basically an electromagnet in this instance ) takes a finite amount of time reach full strength ( time constant ... which is governed by the resistance and inductance of the coil ) it is necessary to allow a sufficient gap between magnets to allow time for the coil to both gain and loose its magnetism.

This gap between the magnets and the inductance/resistance of the coil also govern the final optimum drive speed
( i believe i have covered this in greater detail elsewhere )

So basically i'm sure you already know the answer , but we may have helped a few others in the right direction.

All the best
ron


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Luciano
Average Member



212 Posts

Posted - April 14 2014 :  16:53:41  Show Profile Send Luciano a Private Message  Reply with Quote
Thanx ron.. i wasnt really sure because those magnets seem really close in that video.
I want to do some high frequency experiments so i need as many magnets as possible as close together as possible.
the limit is always the diameter of the rotor the bigger the slower. :-(
so I have been thinking that a 30 cm diameter rotor could have like 32 2cm magnets. at 2000 rpm that would give a frequency of 1066 Hz... i think that would give me the possibility of testing acceleration under load etc...

Luc
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ron_o
Moderator



United Kingdom
1052 Posts

Posted - May 07 2014 :  15:32:15  Show Profile Send ron_o a Private Message  Reply with Quote
The Toroid Core

An example calculation based on an actual core that i was using in an experiment

Core outer diameter = 121 mm ( 0.121 metres )
Core inner diameter = 100 mm ( 0.100 metres )
Core depth = 25 mm ( 0.025 metres )
Core cross sectional area = 0.0105 x 0.025 metres^2 = 2.625 x 10exp-4 metres^2
Core relative permeability ( Ur ) = 122

Number of coil turns ( N ) = 280

Steady state current ( I ) = 0.80 amps

Now for the calculations:-

Magneto Motive Force ( MMF ) = number of coil turns x steady state current
MMF = 280 x 0.8 = 224 Ampere turns

Magnitude of Magnetizing Field Strength ( H )

H = number of coil turns x steady state current / core circumference

H = 280 x 0.8 / 0.121 x Pi = 224 / 0.380 = 589.47 Amps per metre

PLEASE NOTE....

The above calculation of "H" is based upon the assumption that a uniform field exists within the core , this is however not always the case

Flux Density within the core ( B )

B = Ur x Uo x H

where Ur = core permeability and Uo = permeability of air ( 4 Pi 10exp -7 )

B = 122 x 4 Pi 10exp -7 x 589.47 = 0.0903 Tesla

The Total Flux in the core = core cross sectional area x Flux Density

Total Flux = 2.625 x10exp-4 x 0.0903 = 2.37 x 10exp-5 Wb
urns
Flux Linkage ( this is the sum of the Flux linkage of each coil turn or winding )

Flux Linkage = 280 x 2.37 x 10exp-5 = 6.637 x 10exp-3 Wb.turns


Inductance = Flux Linkage / steady state current
Inductance = 6.637 x 10exp-3 / 0.8 = 8.296 x10exp-3 Henrys

And finally the information i required......

Magnetic Energy Stored in Core ( E ) in joules

E = 0.5 x Coil inductance x current^2

E = 0.5 x 8.296 x 10exp-3 x 0.8^2 = 2.655 x 10exp-3 joules


ron
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Luciano
Average Member



212 Posts

Posted - October 04 2014 :  01:51:46  Show Profile Send Luciano a Private Message  Reply with Quote
Hi ron,

I am just trying to replicate the gap motor, the one just neutralizing the magnets and using their force.
here the original page,
You must be logged in to see this link.

but others like russ and romerouk have also replicated it and put it on the shelf.. (i do not know why)

here the romerouk replication
You must be logged in to see this link.

and here russ's replication
You must be logged in to see this link.

they all worked but were only proof of concept, not anyone trying to push it further... the inventor claims OU, but says he is to old to continue...

now after having seen gotolucs new motor concept.. i had some ideas and have started to replicate the gap motor

For the moment i am testing coils... and have seen that i could get it to work with very low voltage (1,4 volt battery the coil drawing like 2 to 400 milliAmps)

My questions:
... as the goal is to neutralize the repelling force of 2 magnets (stack of 5 magnets left vs 2 magnets on the right side)
i am using 20 kilo disk N45 magnets 30 mm in diameter.

1. can I use the formula you posted on page 1 to calculate the force of an electromagnet able to neutralize the force of the left stack?

(I meen your 4 parts of: Electromagnet :- Optimum dimensions for Maximum Core Field Strength)

we are talking here repelling force between 2 magnets... As its a stack of magnets on both sides, i think i would have to measure the repelling force with a scale rather than using the data of the magnet?

2. should i use a core bigger - smaller or same size as the magnet diameter? or maybe aircore?

Of course i can test things.. but it will take weeks especially if i start on a wrong base.

I just dont want to calculate something that will be totally false not because of calculation mistakes, but because of errors in my way of thinking...
Can you give me a hint to point me in the right direction?

for instance if for 30mm diameter magnets i use a 30mm core the coil would be rather big.. if i use your formula.. like 15 cm diameter.. and have a length of 90mm .. I would have so much wire the resistance would be enourmous.. so I am not sure if that is what i want

Luc


Edited by - Luciano on October 04 2014 06:13:17
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ron_o
Moderator



United Kingdom
1052 Posts

Posted - October 04 2014 :  19:54:48  Show Profile Send ron_o a Private Message  Reply with Quote
Hi Luciano

I have only just noticed your posting ( 00 : 50 on Sunday 5th October ) so i will have to get back to you later today.

I have seen the gap-motor design before and i doubt it can ever achieve over unity ( basically due to the physics of the device ) however i will attempt to answer your questions.

ron
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Luciano
Average Member



212 Posts

Posted - October 05 2014 :  00:27:54  Show Profile Send Luciano a Private Message  Reply with Quote
hi ron.. actually dont hurry... its not that urgent... i actually only posted yesterday...
and i find the fact that you consider answering already wonderful.

actually i also do not think the gap-motor can produce overunity as a motor
... but i had 2 considerations...

Everybody agreed saying it had lots of torque... and I am looking for a linear device that can produce torque for a "sliding generator". I think i would loose lots of energy by converting rotary to linear.

so as there are 5 types of linear motors that I know of.
I am going to test them all... starting with the gap motor.

2. will be the peter lindeman motor... an iron bar in a coil like a piston.. seen it his video: motor secrets.

3. gotoluc's motor concept.. the one he is actually working on: a sliding coil.

4. then i thought of one, the same setup as the gap motor only with a "coil with core" moving on the carriage in the middle instead of the magnets. (a bit like gotoluc's motor but the coils core moving with it.)

5. just a magnet moving between 2 bifilar bedini coils, the coils "shooting" the magnet to the other side like playing pingpong. only the magnet being on a carriage... I had a nice device up an running, only that the magnet was in a tube and not powering a carriage.


the carriage is a plate on 4 linear bearings.. the basic idea is to power that carriage to run the linear generator.
speed is not that important but i do need torque.

Once the motors work, i want to try and use them vertically, so that the gravity can also play its role.

Luc

Edited by - Luciano on October 05 2014 03:07:56
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Luciano
Average Member



212 Posts

Posted - October 05 2014 :  12:51:00  Show Profile Send Luciano a Private Message  Reply with Quote
Just for info... good i didnt wind it...
i did the calculations for a 30 mm core as the magnets have a 30mm diameter..
And i thought i'd use a 0.6mm wire (why? because i have 9 kilos left and other ones i would have to freshly buy)

that would make me..
core: 30 mm
height: 90 mm
winding depth 60mm
windings horiz 150 per layer
100 layers
total turns 15000..
resistance would be about 256 ohms...
coil would be using over 4000 meters of wire,,,

I fear that is not what i should do...

Luc
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ron_o
Moderator



United Kingdom
1052 Posts

Posted - October 05 2014 :  16:37:38  Show Profile Send ron_o a Private Message  Reply with Quote
Hi Luc

Just a quick update...

The stacking of the 5 magnets would ( at least in theory ) produce a flux density of approx 1.84 Tesla ( 18400 Gauss ) which is far greater than the N45 grade can produce / handle.

The equation would be fine to use.

I would suggest that a linear actuator would be the best device ( see also linear motor ) these devices are capable of producing large amounts of force

It is possible to produce high flux density electromagnets by changing the way the coil is wound ( you still need the same number of ampere turns ) this is achieved by using several smaller coils wired in parallel.

Any chance of a rough sketch of your idea / design ( pm me if you wish ) i might be able to assist.

ron
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Luciano
Average Member



212 Posts

Posted - October 05 2014 :  17:04:24  Show Profile Send Luciano a Private Message  Reply with Quote
Well i will if I may turn to you .. my major problem being time...
as i have a quite rough week ahead jobwise, i wont be able to do anything before next week end.
I will then do a short video explaining the concept.
Luc
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ron_o
Moderator



United Kingdom
1052 Posts

Posted - October 08 2014 :  15:25:52  Show Profile Send ron_o a Private Message  Reply with Quote
Yes of course Luc.

Look forward to seeing your video.

ron
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