Unfortunately, I dropped it!

[amdx]

I found a core in my junk box that worked for the
"Designing an interesting inductor"
Here's the physical shape.

> https://www.dropbox.com/s/2bwsxrc58g51yu8/e%20core%20ferrire%20db.jpg?dl=0

As you can see I dropped it and chipped the most important part off
and now it has an air cap.
But, importantly, I found with only 60 turns on the dc coil I could
reduce the inductance down from 100uh to 4uh with under 500ma.
That was using my 100kHz inductance meter, so next I put it on the Q
meter and found it runs out of steam at about 300kHz. Q goes to nothing.
The AsubL of that core was around 2800. That core is about 2" per side
and 11/16" deep, I don't need or want anything that big, but I do need
room for enough turns of larger wire to keep the resistance low.

Where can I buy an ferrite E core that has that shape in a material
with a 2000 or 3000 AsubL, that will work up to 4Mhz, or even higher?

Mikek

PS. I expect any geometry that necks down to a small cross section will
work.

 

[John Larkin]

On Fri, 23 Aug 2019 11:22:26 -0500, amdx <nojunk@knology.net> wrote:

I found a core in my junk box that worked for the
"Designing an interesting inductor"
Here's the physical shape.

https://www.dropbox.com/s/2bwsxrc58g51yu8/e%20core%20ferrire%20db.jpg?dl=0

As you can see I dropped it and chipped the most important part off
and now it has an air cap.
But, importantly, I found with only 60 turns on the dc coil I could
reduce the inductance down from 100uh to 4uh with under 500ma.
That was using my 100kHz inductance meter, so next I put it on the Q
meter and found it runs out of steam at about 300kHz. Q goes to nothing.
The AsubL of that core was around 2800. That core is about 2" per side
and 11/16" deep, I don't need or want anything that big, but I do need
room for enough turns of larger wire to keep the resistance low.

Where can I buy an ferrite E core that has that shape in a material
with a 2000 or 3000 AsubL, that will work up to 4Mhz, or even higher?

Mikek

PS. I expect any geometry that necks down to a small cross section will
work.

Suppose an air gap in a core were filled with some compressible stuff.
A dc field would squeeze it mechanically and reduce the gap hence
reduce the AC inductance.

 

[amdx]

On 8/23/2019 11:22 AM, amdx wrote:

I found a core in my junk box that worked for the
"Designing an interesting inductor"
Here's the physical shape.

https://www.dropbox.com/s/2bwsxrc58g51yu8/e%20core%20ferrire%20db.jpg?dl=0


 As you can see I dropped it and chipped the most important part off
and now it has an air cap.
 But, importantly, I found with only 60 turns on the dc coil I could
reduce the inductance down from 100uh to 4uh with under 500ma.
 That was using my 100kHz inductance meter, so next I put it on the Q
meter and found it runs out of steam at about 300kHz. Q goes to nothing.
 The AsubL of that core was around 2800. That core is about 2" per side
and 11/16" deep, I don't need or want anything that big, but I do need
room for enough turns of larger wire to keep the resistance low.

 Where can I buy an ferrite E core that has that shape in a material
with a 2000 or 3000 AsubL, that will work up to 4Mhz, or even higher?

                                     Mikek

PS. I expect any geometry that necks down to a small cross section will
work.

Sorry, I see you posted but it doesn't open for me (my problem)
So checked googles groups to read it.
That does sound feasible, (probably mechanically more difficult) but I
will keep that in mind, especially since I may run into no-linear mixing
with the core in the flatter part of the B/H curve. I just don't know
that. Your solution would eliminate that possible problem.

Do you have any input on the E core with the reduced cross section at
in one area?

THanks, Mike