Self running coil?

[void109]

I want to try to state this again, to be sure I understand.

If we have our Finemet coil - and we pulse it with x Current, such that the core is saturated (no more room for flux!), we can then, while saturated, lower it toward the magnets 'sweet spot', where by the inductance will increase 300%, its capacity for storing flux by 300%, and we can then store more energy in the magnetic flux?

If that sounds like an accurate description of what this implies - anyone fancy an idea as to where this extra flux gets stored?  Does the presence of this sweet spot perhaps increase the permeability even further (300%)?

I'm sorry if this is derailing the thread, seemed like it may be relevant.  As a side note - instead of fiddling with H-Bridge circuits which arent working out quite how I'd like, I'm just going to run to a second hand store and get a big audio hi-fi amp to amplify the signal from my generators.  No sense in banging my head on those concepts when I'm just trying to research various phenomena.  Any reason that's a bad notion?

-void

[gyulasun]

I want to try to state this again, to be sure I understand.

If we have our Finemet coil - and we pulse it with x Current, such that the core is saturated (no more room for flux!), we can then, while saturated, lower it toward the magnets 'sweet spot', where by the inductance will increase 300%, its capacity for storing flux by 300%, and we can then store more energy in the magnetic flux?

If that sounds like an accurate description of what this implies - anyone fancy an idea as to where this extra flux gets stored?  Does the presence of this sweet spot perhaps increase the permeability even further (300%)?

I'm sorry if this is derailing the thread, seemed like it may be relevant.  As a side note - instead of fiddling with H-Bridge circuits which arent working out quite how I'd like, I'm just going to run to a second hand store and get a big audio hi-fi amp to amplify the signal from my generators.  No sense in banging my head on those concepts when I'm just trying to research various phenomena.  Any reason that's a bad notion?

-void

@void

If you go through again what was written then you find out that nobody meant or implied what you deduced above,  sorry.

I did not write that first you saturate the Finemet core with current then you can increase its inductance by a strong permanent magnet placed near to it in the way you showed in the video.  IF you have read such, please point me to that mail.

Member Gravityblock wrote this, I qouted in bold what is important:

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.
....

So I do not think he meant the opposite sequence as you got it.
First step is to align the magnet wrt the core to cause an inductance increase as much as possible, just to the edge beyond which inductance value collapses down.
Second step is to apply a current which can be a small one to help bring the core into the saturation state (as if you had moved the magnet say half a millimeter closer, to cause the inductance collapse.

The original ORBO concept Luc referred to (when he described his idea for applying this inductance increase you showed to an ORBO-like setup) is that a magnet approaches a toroidal core perpendiculary, saturates that part of the core, then current is introduced into the coil on the core to help deepen the saturation so that the magnet could easily escape from the attraction. 

Hope this helps.

Gyula

[gotoluc]

Hi void,

please don't think this is derailing the thread as this could bring much more light to the topic.  I'm very interested and I'm sure others are also.

Using an Audio amp is a good idea for frequencies below 20Khz

I can't help you with your question as I'm not sure it was explained like that. I think Gyula tried to make it clearer. One way or the other it's best to test and see the results to learn.

Looking forward to a test video

Thanks for sharing

Luc

[gyulasun]

...
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

Hi Luc,

The so called A_L value for the Ferroxcube core is 11400nH/N² (taken from the Farnell link). If you wound 24 turns on it then the formula for L is L=N²*A_L=24*24*11.4=6.566mH
You measured 9mH instead, this difference can only be explained by a high manufacturing tolerance. 
On you other 'usual'  core you got 1.22mH for the 30 turns from the same length of wire. If I recall the A_L value I calculated for your core is A_L=1298.6nH/N²   This gives 30*30*1.2986=1.168mH, very close to your measured 1.22mH.

The big difference comes from the big A_L value differences. Putting it otherwise: the Ferroxcube core has a much higher permeability than the other core.  (7730 vs 1196)

rgds, Gyula

[void109]

Oh I wasnt saying anyone proposed that example, that was just a thought experiment on my part - given assertions that were made, which were:

1 - Higher inductance means it takes more current to saturate the core (?)

2 - Saturation means that the core material cannot contain any further flux (?)

3 - The inductance of the coil increases in a certain position and arrangement relative to the permanent magnet (?)

4 - If the saturation increases - that implies that the coil now has increased capacity to contain further flux (?)

Those are my assumptions based on my current understanding.

So what I said before was a thought experiment based on the above postulates - if any of those assertions are wrong - please tell me    And number 3 is just from my own experiment, the first two are factoids I've gleaned from folks here more knowledgeable than myself like you fine gentlemen.  The thought experiment just outlined my confusion as to the *how* the inductance can rise given its proximity to the magnet.  I appreciate the feedback.