North American Ferrite core supplier for prototypes

[Spehro Pefhany]

Any suggestions for a North American supplier with a good online
presence? Tiny to large E/RM/Pot core etc.

Most of the distributors and agents seem to have high minimum orders,
no online stock checking, no online ordering etc. etc. just like in
the 1970s. There's one within 15 minutes of my office, plenty of
stock, but they want C$100 per *line item* minimum order (clamps,
bobbins and cores are 3 line items...).

The only thing that seems to have changed with the internet is all the
data and application notes are now online. I don't want to deal with
surplus houses, the product needs to be known brand name stuff that
can be had in production quantities.

Joerg?


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Boris Mohar]

On Thu, 02 Jun 2005 22:05:59 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

http://www.neosidcanada.com/company.htm

One time they cut and ground me few pieces for a custom job. Very
approachable. None of this " And how many million will you be planning to
purchase from us in the future"

Was that recently, Boris?

No, actually it was about six years ago.

--

Boris Mohar

 

[Joerg]

Hello Graham,

Do you need one in your case though ? Split bobbins can be hard to find.

At Kaschke that is a regular catalog item, at least for pot cores.

Regards, Joerg

http://www.analogconsultants.com

 

[Sergey Kubushin]

Joerg <notthisjoergsch@removethispacbell.net> wrote:

Hello Graham,

Do you need one in your case though ? Split bobbins can be hard to find.

At Kaschke that is a regular catalog item, at least for pot cores.

BTW, does anybody know where I can buy small amount of _transformer steel_
EI lamination? Its not such a difficult thing to find ferrite, iron powder
or similar core but I can't find transformer steel anywhere... I want to
wind several (4-8) _output_ transformers for tube amplifiers. I can't find
any ready-made transformers that suit my needs and all those custom-wound
ones are helluva expensive. I would've even try to rewind some surplus ones
but they are all varnished that makes such a task next to impossible (

---
******************************************************************
* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
******************************************************************

 

[Joerg]

Hello Sergey,

BTW, does anybody know where I can buy small amount of _transformer steel_
EI lamination? ...

Other than buying a few cheap transformers and taking them apart I
wouldn't know off hand. That is usually how I did it. You could start a
separate thread about it so more people would see it.

Regards, Joerg

http://www.analogconsultants.com

 

[Spehro Pefhany]

On Fri, 03 Jun 2005 17:29:16 GMT, the renowned Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Hello Sergey,

BTW, does anybody know where I can buy small amount of _transformer steel_
EI lamination? ...

Other than buying a few cheap transformers and taking them apart I
wouldn't know off hand. That is usually how I did it. You could start a
separate thread about it so more people would see it.

Carpenter is one of the big guys, but steel suppliers are a major PITA
to deal with. A few years ago it was a $500 minimum, probably more
now. Maybe you can sweet-talk them into giving you some samples.

Many years ago some outfit in the UK had transformer "kits" with the
primary pre-wound, you just have to add the secondary. Don't know if
they're still available. I bought a few from Maplin.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Joerg]

Hello Spehro,

Many years ago some outfit in the UK had transformer "kits" with the
primary pre-wound, you just have to add the secondary. Don't know if
they're still available. I bought a few from Maplin.

That was also one of the advantages of taking apart existing
transformers. Preferably some with lower voltage secondaries because it
was less work to unwind those. Then you had the primary already there,
120V/240V taps and all.

But Sergey wants to create tube amp output transformers and that would
almost certainly require a complete rewind. Unless one would find the
perfect match where the primary shows just the desired impedance and a
120/240 split if he has to design push-pull.

If I were in his shoes I'd seriously consider one of the hi-perm
ferrites. Preferably some huge pot core for easier winding. These
materials have come a long way since the days of tube amps. I believe
you could get a lot more fidelity out of them. Also, the round bobbins
allow to fix them to an electric drill chuck and wind'em up at slow
speed. I never really succeeded doing that with square bobbins but in
those days the only way to slow down a drill was via a variable
transformer and then it would sputter at very low speeds.

Regards, Joerg

http://www.analogconsultants.com

 

[Zak]

Joerg wrote:

One of the radios still contained a Ducati capacitor even though their
biz moved to motorcycles decades before. Hidden inside was a new Philips
cap.

There are/were recently still caps being made under the Ducati name. See
http://www.baco-army-goods.nl/condensator%20pag-1.htm
for surplus 400 volt AC caps with VDE mark


Thomas

 

[Joerg]

Hello Thomas,

There are/were recently still caps being made under the Ducati name. See
http://www.baco-army-goods.nl/condensator%20pag-1.htm
for surplus 400 volt AC caps with VDE mark

Interesting. And they state that it is from current production runs, not
old stock. It looks like it is from Ducati-Energia. I don't know about
how the companies are linked these days but they are in Bologna just
like the motorcycle manufacturer. Plus there are lots of other products
under that name, parfumes etc.

Regards, Joerg

http://www.analogconsultants.com

 

[Pooh Bear]

Sergey Kubushin wrote:

Joerg <notthisjoergsch@removethispacbell.net> wrote:
Hello Graham,

Do you need one in your case though ? Split bobbins can be hard to find.

At Kaschke that is a regular catalog item, at least for pot cores.

BTW, does anybody know where I can buy small amount of _transformer steel_
EI lamination? Its not such a difficult thing to find ferrite, iron powder
or similar core but I can't find transformer steel anywhere... I want to
wind several (4-8) _output_ transformers for tube amplifiers. I can't find
any ready-made transformers that suit my needs and all those custom-wound
ones are helluva expensive. I would've even try to rewind some surplus ones
but they are all varnished that makes such a task next to impossible (

The E-I laminations used in a power transformer aren't ideal for an audio
output transformer of any fidelity.

The laminations in an audio output transformer should be thinner ( higher
frequency eddy current losses ) and ISTR that the preferred matereial grade
differs too.

That probably explains the higher costs ( not to mention small quantities ).

You might fare better with a toroidal core ( thinner material anyway and I
think it's generally higher quality ). You'll need more turns/Volt than at
power line frequency too since you'll want the thing to work down to 20Hz I
assume.

Graham

 

[Fred Bloggs]

Spehro Pefhany wrote:

Any suggestions for a North American supplier with a good online
presence? Tiny to large E/RM/Pot core etc.

I have used these people for prototype quantities, they are
knowledgeable and responsive, and the products are solid and ready to
mount. Why wind it yourself?

http://www.coilws.com/

 

[Tony Williams]

In article <42A0F890.7F60BEB6@hotmail.com>,
Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:

The E-I laminations used in a power transformer aren't ideal for
an audio output transformer of any fidelity.
The laminations in an audio output transformer should be thinner
( higher frequency eddy current losses ) and ISTR that the
preferred matereial grade differs too.

The famous Williamson audio amplifier specified the
use of "dynamo grade laminations". Iron losses were
not seen as a problem for power output transformers
and 0.015" lams in 4% silicon steel were often used.

Low level transformers would need the higher permeability
provided by nickel-iron cores (to avoid excessive turns
count), and probably using thinner laminations.

You might fare better with a toroidal core ( thinner material
anyway and I think it's generally higher quality ). You'll need
more turns/Volt than at power line frequency too since you'll
want the thing to work down to 20Hz I assume.

The biggest problem with a lamination transformer
at audio frequencies was the hf rolloff due to the
leakage inductance. Toroidal transformers send
most of that problem away.

--
Tony Williams.

 

[Joerg]

Hello Tony,

The biggest problem with a lamination transformer
at audio frequencies was the hf rolloff due to the
leakage inductance. Toroidal transformers send
most of that problem away.

While I also prefer toroids, the large number of turns required for a
tube output transformer would entice me to use a pot core with bobbin in
this case.

Regards, Joerg

http://www.analogconsultants.com

 

[Pooh Bear]

Joerg wrote:

Hello Tony,

The biggest problem with a lamination transformer
at audio frequencies was the hf rolloff due to the
leakage inductance. Toroidal transformers send
most of that problem away.

While I also prefer toroids, the large number of turns required for a
tube output transformer would entice me to use a pot core with bobbin in
this case.

You'ld need something rather larger than a pot core ! ;-)

Graham

 

[Joerg]

Hello Graham,

You'ld need something rather larger than a pot core ! ;-)

Depends on the power and DC load. There are pot cores where you almost
need a small crane to install them ;-)

Regards, Joerg

http://www.analogconsultants.com

 

[Pooh Bear]

Joerg wrote:

Hello Graham,

You'ld need something rather larger than a pot core ! ;-)

Depends on the power and DC load. There are pot cores where you almost
need a small crane to install them ;-)

Not the RM series then ?

Graham

 

[Joerg]

Hello Graham,

Depends on the power and DC load. There are pot cores where you almost
need a small crane to install them ;-)

Not the RM series then ?

No

Once the top half accidentally slid off and hit my hand. I sported a
blue/black thumb nail for months.

Regards, Joerg

http://www.analogconsultants.com

 

[Winfield Hill]

Joerg wrote...

Depends on the power and DC load. There are pot cores where
you almost need a small crane to install them ;-)

Not the RM series then ?

No Once the top half accidentally slid off and hit my hand.
I sported a blue/black thumb nail for months.

What a wimp.

No doubt my 600kHz 10kV paralleled-U-core transformer rates up
among the biggest out there in dilettante land, but it's no more
massive than an old 60Hz 1kW plate transformer. Get a grip man!


--
Thanks,
- Win