Magnet Inductance Boost with Finemet nanocrystaline core

[Kator01]

Hello ,

please note the difference between square lopp cores and metglas:

the finemet core, see description : supressing surge in current and voltage

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

square lopp cores are designed for magnetic amplifier applications.

Do not get confused. Modern Electronic components are specifically designed for distinctive applications.

Damping and controlling by saturation is something of a big difference.

So using it for new exotic applications such as the muller-gen you have to know which is doing what.

Kator01

[gotoluc]

Hi Luc
               With regards to the increase of core inductance,This is quite normal.as these
  cores are "Square Loop" .Bringing the core close to a bias magnet will push it into
a high permeability zone of the core.For your interest this effect will also occur  in other non tape wound cores ,but are Square Loop..i know this having worked with square loop cores in the construction computer memory stores in the 1950`s.
You will find the toroid's make really good pulse motor drivers.
also check this out.

http://www.metglas.com/downloads/finemet_magamp.pdf
Just another point 3R1 cores are a lot cheaper than the tape wound.Here is some info.http://www.ferroxcube.com/appl/info/square.pdf
Also if you are in the UK you can get them from |Farnell
Best Regards Dave

Hi Dave,

thanks for looking at this topic and posting your comment.

I have this model of FERROXCUBE: http://uk.farnell.com/jsp/search/productdetail.jsp?SKU=3057010

However, I tried it before starting this topic and a magnet does not boost its Inductance. So I cannot accept your conclusion at this point that this happens in Square Loop cores. Something is different with the Finemet core.

Please try it yourself and report your findings

Thanks for sharing

Luc

[gotoluc]

Hi Luc,

lecture on kinetic inductance Lk. Pay notice to his remark about thin-films. This finemet inductors are made from thin-film-layers.

http://www.youtube.com/watch?v=MAHkYROmriY&feature=related

Besides this- there is no increase in the inductance as the negative spike amplitude is decreased. Also the area the first curve containes is also decrease meaning : the magnetic energy is reduced. The meter is fooled as the oscillation is damped as it is clearly seen in you vid. The higher fourier-components 2nd, 3 rd and 5 th are strongly damped. Look at the decreasing slope and the damping of the negative overshoot at the cut-off.
These finmet-core are especially designed for damping high frequencies running along conductors and doing their job well.

This physicist should know this.

These cores are interesting in that you can use them for delaying the collapse-time of the magnetic field whe used in series with the coils in a mull-generator - thus one will be able to control the point in time the anti-lenz appears.

Regards

Kator01

Thanks Kator01 for looking at this topic and posting your comments.

I will look into this some more.

One thing is for sure that when a PM is close these cores delay the flyback. Just this effect could be worth something.

Do you know or can explain why it uses much less current when a PM field is applied?

Thanks for sharing

Luc

[firlight]

Hi Dave,

thanks for looking at this topic and posting your comment.

I have this model of FERROXCUBE: http://uk.farnell.com/jsp/search/productdetail.jsp?SKU=3057010

However, I tried it before starting this topic and a magnet does not boost its Inductance. So I cannot accept your conclusion at this point that this happens in Square Loop cores. Something is different with the Finemet core.

Please try it yourself and report your findings

Thanks for sharing

Luc

Hi Luc
            I measured the increase in inductance in Square loop  cores about four
years ago when playing around with Steorns Orbo.Any way I did a quick test again
It was what I expected with the same core I used then.
26.5mH no magnetic bias 33.8mH with Magnetic Bias.With Square loop the increase
of inductance will remain until it is reset by a reverse bias.As you can see the increase is not as great as your tape wound core,but that is to be expected being made from a more exotic material.The answer to your question why is there a reduction in current when your core is biased,is because the inductance has increased therefore so has the impedance .When you bias your core as shown in your Vid, does the inductance remain high when you remove the bias magnet?

Regard Dave

[firlight]

Hello ,

please note the difference between square lopp cores and metglas:

the finemet core, see description : supressing surge in current and voltage

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

square lopp cores are designed for magnetic amplifier applications.

Do not get confused. Modern Electronic components are specifically designed for distinctive applications.

Damping and controlling by saturation is something of a big difference.

So using it for new exotic applications such as the muller-gen you have to know which is doing what.

Kator01

Hi Kator
           Just looked at the link to Metglas ,I don`t quite get what you mean,about the difference,in the type of core.Metglas is the name of the Company.
It looks like to me Square Loop and surge suppression use the same core ,click on the the data link on that page.

Regards Dave