Hi Luc,

unfortunately I have not so much time to go into great length of explanation. But I will try to make it understandable.
You have to somehow find some literature to understand the BH-diagram. because It is essential for further understanding what is going on.

First:    comparison of areas of both curves
Your coil is running idle in both cases. This does not show a real situation. It will be different under load that is current draw by a secondary coil or physical movement towards a pm  or away from it.
 
Second:  you do not know where the zero-line is in the second curve because you have the static pre-magnetization left in the core ( after puls off ) due to your pm attached to it. I am sure the curve is above the zero-line, meaning in the positive area of induced voltage. It must be so. If you would remove the pm from your coil after switching off the puls, only then will you see the whole picture.
But this is impossible to to.

If you look at the pic I attached to my post , the full BH diagram is the dynamic path of sinuswave-current flowing in the coil. For a DC-Puls - as you have applied it - only that part of the curve is valid which is above the horizontal zero-line ( Middle diagram)  As the fieldstrength rises ( Ampere Turns per Meter ) while the puls increases the current in the coil so does the induced Voltage per second = B. It rises steep first and enters the saturation-area where the curve gets more flat.
If puls is cut off the the upper left part of the BH-curve is valid. At that time current from your puls-generator  stops and the magnetic field collapses creating the negative spike. So the current you had to spent is 230 mA as you stated.  You have not spent current for reversal of magnetization because you just stopped the current  while an ac-current would continue to demagnetize to zero and further on to the negative side consuming more power

Now if you magnetize your core with a permanent-magnet the BH-curve starts at the level of the arrows either in the positive side ( above the horizontal level) or the negative side depending on the  pm-pole facing your coil. Lets assume your pre-magnetization has shifted the level above zero. Then this means your puls-current starts here and does not have to magnetize up to this arrow- level in the first place thus not using so much current. You reach the saturation level with less current.
As I said before symmetric pre-magnetization like you did in a torus-core will bring about a different behavior than in a solenoid which is magnetized along its axis. It can not be compared.

For any valid test you have to repeat this pre-magnetization and pulsing using a solenoid which is at the same time moving by another magnet, as in the muller device
It does not make sense this way – of course depending if you like to find something out about muller-principle or some basics about  torus-core-coils with different materials.

Regards

Kator01

Hi Luc,

unfortunately I have not so much time to go into great length of explanation. But I will try to make it understandable.
You have to somehow find some literature to understand the BH-diagram. because It is essential for further understanding what is going on.

First:    comparison of areas of both curves
Your coil is running idle in both cases. This does not show a real situation. It will be different under load that is current draw by a secondary coil or physical movement towards a pm  or away from it.
 
Second:  you do not know where the zero-line is in the second curve because you have the static pre-magnetization left in the core ( after puls off ) due to your pm attached to it. I am sure the curve is above the zero-line, meaning in the positive area of induced voltage. It must be so. If you would remove the pm from your coil after switching off the puls, only then will you see the whole picture.
But this is impossible to to.

If you look at the pic I attached to my post , the full BH diagram is the dynamic path of sinuswave-current flowing in the coil. For a DC-Puls - as you have applied it - only that part of the curve is valid which is above the horizontal zero-line ( Middle diagram)  As the fieldstrength rises ( Ampere Turns per Meter ) while the puls increases the current in the coil so does the induced Voltage per second = B. It rises steep first and enters the saturation-area where the curve gets more flat.
If puls is cut off the the upper left part of the BH-curve is valid. At that time current from your puls-generator  stops and the magnetic field collapses creating the negative spike. So the current you had to spent is 230 mA as you stated.  You have not spent current for reversal of magnetization because you just stopped the current  while an ac-current would continue to demagnetize to zero and further on to the negative side consuming more power

Now if you magnetize your core with a permanent-magnet the BH-curve starts at the level of the arrows either in the positive side ( above the horizontal level) or the negative side depending on the  pm-pole facing your coil. Lets assume your pre-magnetization has shifted the level above zero. Then this means your puls-current starts here and does not have to magnetize up to this arrow- level in the first place thus not using so much current. You reach the saturation level with less current.
As I said before symmetric pre-magnetization like you did in a torus-core will bring about a different behavior than in a solenoid which is magnetized along its axis. It can not be compared.

For any valid test you have to repeat this pre-magnetization and pulsing using a solenoid which is at the same time moving by another magnet, as in the muller device
It does not make sense this way – of course depending if you like to find something out about muller-principle or some basics about  torus-core-coils with different materials.

Regards

Kator01

Thanks Kator01 for taking the time to better explain this.

It is beginning to make more sense! I'll let it digest for some time and reread again later.

Thanks for sharing

Luc

Hey Luc

I think the answer as to how and why is more complicated than just saying it increases inductance.  To test, run a slow freq sweep to the coil, no magnet , then sweep with the mag, and watch the scope. There may be differences at different freq than just measuring a larger inductor.

Have you tried the magnet to the outside of the core, like I did on the orbonbon? I even had multiple mags on the outer core that gave it an advantage for different configs.

Good to see ya back in action. ;]

Mags

...
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.
...

Hi Luc,

Reading back last weeks posts I notice your link above shows a 3E5 material type core which has no square loop curve...  so maybe this explains why you have not got increase in inductance with it?

Dave referred to 3R1 material type that has square loop curve, Farnell has it:
http://uk.farnell.com/ferroxcube/tn23-14-7-3r1/ferrite-core-toroid-3r1-24mm/dp/179443 


They have with OD 36 mm too but at a much higher price:
http://uk.farnell.com/ferroxcube/tn36-23-15-3r1/ferrite-core-toroid-3r1-37mm/dp/179444

Gyula

Thanks for looking at the topic and posting your reply Gyula

I thought these ferroxcube were the same other than size. I'm not going to buy more just to see if Dave is right. Also his Inductance gain was minimal so I don't know why it would be worth it.

What do you think of the Finemet test I did? do you see anything worth testing any further?

Do you agree with Kator01 explanation?

Do you agree with Dave's explanation?

Do you have your own explanation?

Do you think I should take apart the Finemet toroid tape and cut strips to make a solenoid style coil as Kator1 suggests to test it as motor or generator coil?

Sorry for all the questions but I need a little help on which direction to take next

Thanks for sharing

Luc

Hi Luc
             Why don`t you use your toroid as a pulse motor driver they don`t half
motor you can get up to 10000 rpm no problem,use it edge on.
Regards Dave

Hi Dave,

not sure I know what you mean by "they don`t half
motor" and "use it edge on"






Can you post more details, illustration or link so I can see what it looks like.

Thanks for sharing

Luc

Hi Luc
              English slang sorry!  "Dont half motor" means moves fast,speeds up.
have to go to the dentist now,will post pic later.

regards Dave

Here is pic of toroid motor looking down edge of toroid facing magnets on rotor.