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Author Topic: Self running coil?  (Read 302286 times)

Tito L. Oracion

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Re: Self running coil?
« Reply #510 on: April 08, 2010, 09:51:00 AM »
delays, delays, delays.  ;D

delays are bad trips in human attitude but they are very important to make a working self running coil.  ;D

gravityblock

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Re: Self running coil?
« Reply #511 on: April 08, 2010, 11:26:29 AM »
Hi Gyula,

The core is MP1305LF3T

http://www.metglas.com/products/page5_2_2_3_3.htm

The Finemet manufactured from Metglas is a (FT-3AH) and is a square loop core, http://www.scribd.com/doc/28763938/FineMet-Materials

I suspect the inductance is increasing until the core is right below the "knee" of the B-H Curve. Any further increase in saturation from this point, then the core's inductance will decrease.

This means if the magnet is placed at a distance where the inductance is the highest in this core material, then it will take very little input energy to fully saturate the core.

I pushed Finemet extremely hard in the main Orbo thread, but it did not get tested (if it did, then nobody released their test results).  Nanoperm, Metglas, and other square loop cores should have similar results.

Metglas and Finemet are sister companies.  There are restrictions when ordering Finemet, so there may be delays.  Here's an on-line inquiry form for Finemet, http://www.hitachi-metals.co.jp/e/cntct/indx_cntct2.html

GB

gyulasun

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Re: Self running coil?
« Reply #512 on: April 08, 2010, 12:06:00 PM »
I'm no expert but if you can close to triple the inductance of a coil by introducing the center of a permanent magnet that sounds good to me.

One use I can think of is a PM attraction motor. The magnet is attracted to the Finemet toroid core (free work) and when it reaches TDC the coil is energized to release the magnets attraction to the A. Since you can close to triple the inductance of a coil using this Finemet core when the magnet is in the ideal location that it needs to be anyways for best results with this magnet motor design to work, the bonus will be that the coils electromagnetic field will be close to 3 times stronger without using more wire length which adds resistance and longer magnetic field reactance time.

It all looks like a win win situation for this kind of thing to me!

@Gyula, what do you think? Sounds like an ORBO ;D

Luc

ADDED

One thing you may want to check is to what inductance the same length of wire can produce on a regular ferrite core of the approximate same size. If it's as high as you can get the Finemet using the magnet then maybe it's not all that great but if it's the same 25mH then I think this is very good. Please let us know of your results.

Hi Luc,

If the ORBO principle takes any advantage from core saturation caused by just the closeness of permanent magnets at a moment and this saturation helps reduce the input current need for reaching full or enough saturation to let the rotor escape from the attraction,  then the idea of increasing the inductance when the magnet(s) are close to the core sounds counterproductive because higher inductance demands higher input current to do saturation (if comparing to the previous ORBO example).  Somehow you have to defeat the extra flux the core possibly collected inside its volume from the strong magnet.
Of course this is what I think and the best would be to see the B-H curve of such core on a scope when the coil's self inductance on it has increased to a higher value due to a nearby magnet, how it would look like.

Maybe this inductance increase could be beneficial at your pulse coil in the oscillator because the copper loss could be decreased by using less wire for the given inductance needed for the oscillator. 

By the way, would you tell the DC resistance of the pulse coil you have used in your latest oscillators? I think it is the coil from a shaded pole motor and you tune it by a ferrite rod?

I wonder if you tried a normal toroidal core for the pulse coil between the gate-source electrodes? Or the toroidal core's tuneabilty by a magnet may  not give as a flexibility as the ferrite rod does?

Or a toroidal core has a much higher Q than the high DC Ohm motor coil and makes tuning (oscillating at all) very cumbersome?  I ask these because the resonant voltage across the gate-source surely depends also on the Q of the resonant circuit. Maybe you have found a certain low (or max a medium) Q value you have at present that  gives these <10uA results from the 3V and increasing the Q here would not be beneficial.

rgds,  Gyula

EDIT:  Luc, when I wrote on the higher current need for a higher inductance above I did not know this core has a square loop B-H curve. See my following letter to gravityblock too.
« Last Edit: April 08, 2010, 12:27:19 PM by gyulasun »

gyulasun

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Re: Self running coil?
« Reply #513 on: April 08, 2010, 12:19:11 PM »
The Finemet manufactured from Metglas is a (FT-3AH) and is a square loop A, http://www.scribd.com/doc/28763938/FineMet-Materials

I suspect the inductance is increasing until the core is right below the "knee" of the B-H Curve. Any further increase in saturation from this point, then the core's inductance will decrease.

This means if the magnet is placed at a distance where the inductance is the highest in this core material, then it will take very little input energy to fully saturate the core.

I pushed Finemet extremely hard in the main Orbo thread, but it did not get tested (if it did, then nobody released their test results).  Nanoperm, Metglas, and other square loop cores should have similar results.

Metglas and Finemet are sister companies.  There are restrictions when ordering Finemet, so there may be delays.  Here's an on-line inquiry form for Finemet, http://www.hitachi-metals.co.jp/e/cntct/indx_cntct2.html

GB

Hi GB,

Thanks for the links, and if these cores has a square loop-like B-H curve indeed than I have to modify my previous letter to Luc because I did not consider in my answer to him the core type had a square loop curve.

Indeed then the coil wound on such a core would surely need a very little input current to get full saturation so that the magnet on the rotor could escape very easily from the attraction situation.

Thanks, Gyula

teslaalset

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Re: Self running coil?
« Reply #514 on: April 08, 2010, 12:23:43 PM »
FYI, I have encountered same effects on MetGlas cores a few weeks ago.
So, it's not only FineMet that shows this effect.
And I would not be surprised if this effect also works for normal ferrite cores.

The external magnet changes the B-H curve of the core material.
Changing the B-H curve means changing the permeability curve, and thus changing the coil value.

Note, that the optimum distance between magnet and toroid is dependent on the current being used (e.g. to measure the coil value).
This means that optimum distance can be different between the measured situation and the real 'in use' situation.
Using a DSO can help you to easily optimize the optimum distance for the 'in use' case (optimize the maximum current delay to a voltage step to find the maximum coil value).

mscoffman

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Re: Self running coil?
« Reply #515 on: April 08, 2010, 03:04:09 PM »
I have contacted Stefan about this user. All 14 of his posts are this kind of stuff ::)

> Good.

I don't have a feeling his stay here will be a long one ;)

> I don't know...computers can be very persistant...Gigo. :)

Luc

gotoluc

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Re: Self running coil?
« Reply #516 on: April 08, 2010, 05:34:59 PM »
Hi Luc,

If the ORBO principle takes any advantage from core saturation caused by just the closeness of permanent magnets at a moment and this saturation helps reduce the input current need for reaching full or enough saturation to let the rotor escape from the attraction,  then the idea of increasing the inductance when the magnet(s) are close to the core sounds counterproductive because higher inductance demands higher input current to do saturation (if comparing to the previous ORBO example).  Somehow you have to defeat the extra flux the core possibly collected inside its volume from the strong magnet.
Of course this is what I think and the best would be to see the B-H curve of such core on a scope when the coil's self inductance on it has increased to a higher value due to a nearby magnet, how it would look like.

EDIT:  Luc, when I wrote on the higher current need for a higher inductance above I did not know this core has a square loop B-H curve. See my following letter to gravityblock too.

Yes Gyula thanks, I see you have reconsidered this. I will see if I can buy a large Finemet toroid to further experiment with it.

Maybe this inductance increase could be beneficial at your pulse coil in the oscillator because the copper loss could be decreased by using less wire for the given inductance needed for the oscillator. 

Yes!  I definitely agree, this maybe much better then what I have at this time. Needs to be tested.

By the way, would you tell the DC resistance of the pulse coil you have used in your latest oscillators? I think it is the coil from a shaded pole motor and you tune it by a ferrite rod?

I'm glad you ask this!  because it's hard to believe. Yes it is a shaded pole motor inductor that I use as pulse coil because it's easy to adjust the exact inductance needed by just sliding in or out a long ferrite rod that I made by super gluing 2 AM radio loop stick antenna ferrite rods together. With it I can vary the inductance from 35mH to 350mH. Anyways, it's DC resistance is 67 Ohms. I know many will say that it's a waste of energy but I tried it with my single wound 6.9 Ohm toroid coil and I see no difference. Perhaps because at resonance the coils resistance is not seen? Let me know what you think of this.

I wonder if you tried a normal toroidal core for the pulse coil between the gate-source electrodes? Or the toroidal core's tuneabilty by a magnet may  not give as a flexibility as the ferrite rod does?

Yes I tried the pulse coil with the toroid as stated above but found no gain.

Or a toroidal core has a much higher Q than the high DC Ohm motor coil and makes tuning (oscillating at all) very cumbersome?  I ask these because the resonant voltage across the gate-source surely depends also on the Q of the resonant circuit. Maybe you have found a certain low (or max a medium) Q value you have at present that  gives these <10uA results from the 3V and increasing the Q here would not be beneficial.

rgds,  Gyula

I don't know much about coil Q so I don't know what to answer ???

Hope what I could answer helps.

Luc

void109

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Re: Self running coil?
« Reply #517 on: April 08, 2010, 05:45:10 PM »
Being new to electronics, if someone could point me toward how to build a circuit to see a B-H curve on my scope, I'll take video of the curve rendered by the core when under influence of the magnet and without.

My scope has the option of plotting via X/Y inputs.

gotoluc

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Re: Self running coil?
« Reply #518 on: April 08, 2010, 05:49:21 PM »
FYI, I have encountered same effects on MetGlas cores a few weeks ago.
So, it's not only FineMet that shows this effect.
And I would not be surprised if this effect also works for normal ferrite cores.

The external magnet changes the B-H curve of the core material.
Changing the B-H curve means changing the permeability curve, and thus changing the coil value.

Note, that the optimum distance between magnet and toroid is dependent on the current being used (e.g. to measure the coil value).
This means that optimum distance can be different between the measured situation and the real 'in use' situation.
Using a DSO can help you to easily optimize the optimum distance for the 'in use' case (optimize the maximum current delay to a voltage step to find the maximum coil value).

Hi teslaalset,

thanks for posting your findings :)

Can you help me with what I would need to do to setup my DSO scope to measure this. I have no electronics background so I don't know. I've just been learning as I go. I would need an illustration or better a video tutorial as I learn much faster visually.

Thanks for sharing

Luc

gotoluc

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Re: Self running coil?
« Reply #519 on: April 08, 2010, 05:51:43 PM »
Being new to electronics, if someone could point me toward how to build a circuit to see a B-H curve on my scope, I'll take video of the curve rendered by the core when under influence of the magnet and without.

My scope has the option of plotting via X/Y inputs.

Well that makes two of us ;D. It would be great help if someone could make a video tutorial of this.

Luc

gyulasun

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Re: Self running coil?
« Reply #520 on: April 08, 2010, 06:04:48 PM »
Being new to electronics, if someone could point me toward how to build a circuit to see a B-H curve on my scope, I'll take video of the curve rendered by the core when under influence of the magnet and without.

My scope has the option of plotting via X/Y inputs.

Hi Folks,

Here is Naudin tests on this topic, see here, with video too:

http://jnaudin.free.fr/2SGen/indexen.htm#hysteresis

Also, some more info is here:

http://www.cliftonlaboratories.com/type_43_ferrite_b-h_curve.htm

rgds, Gyula

void109

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Re: Self running coil?
« Reply #521 on: April 08, 2010, 06:11:38 PM »
I apologize if I'm just being slow to catch the explanation - but does any of this explain why the inductance **increases** with a specific proximity to the permanent magnet?

If I understand correctly, increased inductance indicates that more current is required to saturate the core?  Where does this excess current get stored?

gyulasun

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Re: Self running coil?
« Reply #522 on: April 08, 2010, 07:28:49 PM »
I apologize if I'm just being slow to catch the explanation - but does any of this explain why the inductance **increases** with a specific proximity to the permanent magnet?

If I understand correctly, increased inductance indicates that more current is required to saturate the core?  Where does this excess current get stored?

Hi void109,

Sorry but I do not know for sure why the inductance increases for your FineMet core.  What I guess is that the paralell arrangement of the core with the magnet's facing side forces the core to 'collect' as much flux as its narrow square loop B-H curve lets, equally inside its full volume, this increases the B inside the core up to a maximum value beyond which saturation suddenly appears. I think it is important here that all the total  volume of the core be imposed to the (nearly homogen) flux coming from the facing magnet.
This parallel setup's behavior is in contrast to the setup where you approach a magnet towards the toroidal core from sideways (perpendicularly): in this case the magnet has the main effect only locally at and near the small volume of the core where the magnet is placed: strong flux, hence partial or full saturation can only be created in that part of the core.  It is like you would have created a virtual air gap in that part of the core you approached/attached the magnet to. Virtually you "open" a toroidal core if you saturate a small volume of it 'locally' by a strong (but small wrt the full core volume) magnet.  This is how I think.

Probably I made the confusion first I was not aware your core has a square loop B-H curve and answered to Luc that increased inductance normally needs higher current, comparing this to his ORBO example where just the opposite happens to the core: in the presence of the magnet the inductance gets reduced due to the core (local) saturation and less inductance has less 'resistance' to current flow than a higher value inductance has. I was thinking generally.

IF you excite a coil's core with current, the current is 'used up' by the wire loss (I2R) and is used up for rearrangeing the domains in the core from their random 'position' to an 'organised' one, the magnetic energy (that was created from part of the input current) is inside the core, the domains store it temporarily. When you switch the current off most of the domains tries to return to their original random state and 'release' the stored magnetic energy, this is the "collapsing flux's case" and this can be collected from the coil if you steer the suddenly induced voltage spike into a capacitor via a fast switching diode.

Maybe I answered you questions.

rgds,  Gyula

gotoluc

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Re: Self running coil?
« Reply #523 on: April 08, 2010, 08:31:35 PM »
Well GB,

here is my update about the Finemet cores. Maybe no one got some because they are next to impossible to buy.

Metglas says their distributor is Elna Magnetics. I called Elna Magnetics and they have no stock, never had. You have to fax them a detailed purchase request and then they will look into it. So I called Metglas and the one person operating this business is away till tomorrow :-\

This does not sound like an available item to me. Nothing else can be found!

User Peterae sent me a Toroid a month ago: http://uk.farnell.com/jsp/search/productdetail.jsp?SKU=3057010 
I was saving it for when I find the ideal winding I want. However, last night I decided to wind it using 1 meter of 30AWG 25mm wire on that core which gave 24 turns. The resulting inductance is 9mH which I found kind of high so I wound the same 1 meter of 30AWG 25mm wire on the ferrite toroid core that I have been using in all my tests and it gives 30 turns. Its inductance is 1.22mH.

I'm confused as to why there is such a big difference. Is it the little bit of extra mass? Peterae Toroid TX36/23/15-3E5: OD 36.30mm, ID 22.55mm, height 15.5mm, width 6.8mm compared to my Regular Toroid I have: OD 34.45mm, ID 20.0mm, height 11.95mm, width 6.85mm

If someone can help explain the difference that would be helpful and appreciated.

Thanks

Luc

teslaalset

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Re: Self running coil?
« Reply #524 on: April 08, 2010, 08:37:37 PM »
Hi teslaalset,

thanks for posting your findings :)

Can you help me with what I would need to do to setup my DSO scope to measure this. I have no electronics background so I don't know. I've just been learning as I go. I would need an illustration or better a video tutorial as I learn much faster visually.

Thanks for sharing
Luc

Sure Luc,

Have a look at my posting at the Steorn discussion thread, posting #2849, here:
http://www.overunity.com/index.php?topic=8411.2835

In Fig 3 Scoop, bottom picture, the delay between the raising edge of the bottom signal (= the signal of the signal generator), and the upward curve of the middle signal in the picture (= measured value of the current through the coil) should be maximized to obtain the maximum coil value.

Some additional explanation of this measurement:
If you switch a voltage over a coil, the current through the coil always lags the start of the voltage step.
The larger the coil value, the larger the delay of the current.
So, by moving the magnet the delay can be optimized and thus the coil value.

Hope this helps. If you need additional explanation, let me know.
(at the time of these finding I used a CRO instead of a DSO)