Super-tiny ferrite rods anywhere?

[Joerg]

Am 21.12.2012 18:05, schrieb Joerg:


Piconics prices are breathtaking.

That would be ok in this case. There'd also be other companies I can
talk to, such as Gowanda.

Plus we just paid $3 for each 95 gram loaf of German marzipan so we are
used to high prices for the good stuff.

Mini Circuits comes to mind.

When I was with Infineon Fiber Optics, I said to a MCL sales man
that they could sell a bias tee for every ERA-8 or so if the
price was right. Seems they listen.
Ok, at least the price is better.

But their stuff is comparably large.

BTW a colleague of mine decided not to wait until the Piconics
samples were here, put ferrite into a mortar, added
epoxy glue and formed some ferrite cores. They were ugly,
but his conical coils where surprisingly good.

Interesting. Maybe I can convince my wife to give me the mortar from the
kitchen. But only after the Christmas baking is done

This inductor does not have to be conical and in fact should not be. We
have to milk every li'l nanohenry we can get.

 

[Joerg]

Am 21.12.2012 18:15, schrieb Joerg:
HAve you contacted Fair-rite (or others)?

You might try Würth, also. They have been quite flexible for
a friend, even for small runs.

Yes, they are good with custom stuff. So is Kaschke in Germany. But
these are the "big iron" companies, they are usually not geared for the
manufacturing of ultra-small components.

When we did our electronic ultrasound catheters we were told by every
high-tech company on the list that it can't be done. Now they are made
by the truckload.

 

[[email protected]]

Plus we just paid $3 for each 95 gram loaf of German marzipan so we are

used to high prices for the good stuff.

Stolen, was it? I used to *love* that stuff. I wish the UK Aldi stores would bring it in for December like they do in Germany.

 

[Joerg]

Stolen, was it? ...

No, my wife obtained those legally and paid. Come to think of it, we
ship them the almonds, they crush them, mix in lots of sugar and spices,
and then ship it back at >10x the price. Maybe I am in the wrong business?

... I used to *love* that stuff. I wish the UK Aldi
stores would bring it in for December like they do in Germany.

Careful, there are major quality differences in marzipan. Some has a
cheap sugary taste, some taste almost to die for. The good stuff from
Luebeck is really expensive even inside Germany.

BTW, your posts appear as copies in my email. Not a problem but I guess
you are one of the guys who have upgraded Thunderbird and must get used
to the new buttons

 

[[email protected]]

Careful, there are major quality differences in marzipan. Some has a

cheap sugary taste, some taste almost to die for. The good stuff from

Luebeck is really expensive even inside Germany.

Aldi UK sell some absolute gems from time to time at rock bottom prices. Quality wise they often top consumer surveys when compared with premium brands. I wish they'd open a store in my town!

BTW, your posts appear as copies in my email. Not a problem but I guess

you are one of the guys who have upgraded Thunderbird and must get used

to the new buttons

My ISP is to blame for this, basically. I'll be changing them after the holidays if they don't sort themselves out. I wonder if Aldi's broadband is available here? ;-)

 

[Baron]

[email protected] Inscribed thus:

Stolen, was it? I used to *love* that stuff. I wish the UK Aldi stores
would bring it in for December like they do in Germany.

Look again ! Our local Aldi and Lidl both have Stollen loaf in !
and Stollen bites too.

 

[Joerg]

If we were dying of thirst in the middle of the Sahara, I might
consider drinking Coors. What's their motto? "It's water."



If you wind the coil on a mandrel, some sort of super-tiny (glass
capillary?) tube could be used to squirt the loaded epoxy inside. Or
just slop it on with a brush.

How thin a wall could a capillary have? They use glass tubes to suck
the nuclei out of cells. A thin-wall capillary could be filled with
ferrite powder, or ferrite-epoxy to make it a little stronger. Then
wind on that.

Some people are making hollow optical fibers. A 120 micron fiber is
about the size you need. A kilometer spool of that might last a while.

120um hollow fiber? Shazam! Do you remember a company name or vendor name?

Now that the Piconics patents have expired, a couple of other people
are making the filled conical inductors. Coilcraft and somebody else.
They are great for bias tees.

Ours don't have to be conical. In fact, shouldn't be.

 

[Fred Abse]

You probably can machine it. For example, leave the sides thick, machine
down only a few millimeters in the center, break thick ends off. Of course
this requires super-balanced machinery and nobody is allowed to sneeze
with 10ft.

How small does centerless grinding go?

 

[Joerg]

How small does centerless grinding go?

I have no idea but it would avoid the risk of breakage by off-axis
forces or imbalances.

 

[Spehro Pefhany]

The Italians buy our wheat for a few dollars a bushel, add water,
remove the water, and sell us the pasta for $4 a pound.

The French buy our mustard seed for a few dollars a bushel, process it
a bit and ship it back at $4 for a few ounces.


Best regards,
Spehro Pefhany

 

[rickman]

I believe these are the same guys who make ceramic nose cones for
missiles and such like-- very capable company.. not sure if they do
ferrites though. AFAIK ferrites require somewhat different processing.

I thought that was Corning, but I guess there could be more than one
company doing it.

Rick

 

[Joerg]

The French buy our mustard seed for a few dollars a bushel, process it
a bit and ship it back at $4 for a few ounces.

Then you visit a French restaurant and the price goes up by another 1000%.

 

[Jasen Betts]

How thin a wall could a capillary have? They use glass tubes to suck
the nuclei out of cells. A thin-wall capillary could be filled with
ferrite powder, or ferrite-epoxy to make it a little stronger. Then
wind on that.

These microscopic tubes are formed by heating until soft and then
stretching a thin glass tube which starts off at about half hole by
diameter, I think the hole to wall ratio is conserved during stretching.

 

[Jasen Betts]

Hello,

Looking for a way to either buy very tiny ferrite rods or have them made
somewhere. Like this:

http://www.fair-rite.com/cgibin/cat...ircuit&THEPART=Antenna/RFID+Rods#select:freq1

Except that we need to get the diameter down 0.004" (0.1mm).

down to or down by?

 

[Gerhard Hoffmann]

Am 22.12.2012 00:02, schrieb John Larkin:

But they do have the technology for getting ferrite epoxy into coils
wound with #40. Wave some serious volume at them and see what happens.

On the time nuts mailing list we recently discussed the wire
that delay lines in TEK 475 & friends were made from.
Requirement was "Lots of L per millimeter"

And with a really slim form factor, there is as much air gap
as way through ferrite, so the ferrite buys a factor of 2
at best.

regards, Gerhard

 

[mi]

Hello,

Looking for a way to either buy very tiny ferrite rods or have them made
somewhere. Like this:

http://www.fair-rite.com/cgibin/cat...ircuit&THEPART=Antenna/RFID+Rods#select:freq1

I discusesed with Valley Design (www.valleydesign.com) at a Optec fair in Germany.
They're doing mostly optical, but your size requirements sound like them and
handling ferrites might be doable by them.

 

[Joerg]

I discusesed with Valley Design (www.valleydesign.com) at a Optec fair in Germany.
They're doing mostly optical, but your size requirements sound like them and
handling ferrites might be doable by them.

Aha, and they are even here in California! Thanks, Mikko. I'll put this
under the Christmas tree, will call them.

 

[Joerg]

Rather than trying to wind a cylinder could one etch a flat spiral from
a 4-ish mil ferrite layer on a nonmagenetic substrate? Just a thought.

Maybe I don't quite understand what you mean. Ferrite is non-conductive,
but we need the inductor to be at least somewhat conductive. If it has a
few ten ohms that would be fine though.

 

[Joerg]

Am 22.12.2012 00:02, schrieb John Larkin:



On the time nuts mailing list we recently discussed the wire
that delay lines in TEK 475 & friends were made from.
Requirement was "Lots of L per millimeter"

And with a really slim form factor, there is as much air gap
as way through ferrite, so the ferrite buys a factor of 2
at best.

A factor of two is HUGE for us. We would open a bottle of Trappiste that
night to celebrate.

 

[[email protected]]

I don't think anyone's suggested this idea yet, so how about rolling out the ferrite cores between two flat plates - glass sheets perhaps? You'd have to absorb or mix ferrite dust into some sort of gummy medium that would be readily roll-able, but if that could be achieved then a pretty much uniform5 thou diameter rod should be easily achievable, I'd have thought. Just keep rolling out and re-rolling until the desired diameter is obtained.