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transformer core

K

Kevin Weddle

Jan 1, 1970
0
What can I use for a transformer core? I think I need a piece of steel
with a large area. The example that I have seen has a large area, not
just length. Do I have to find a steel shop for a core?
 
S

Stefan Heinzmann

Jan 1, 1970
0
Kevin said:
What can I use for a transformer core? I think I need a piece of steel
with a large area. The example that I have seen has a large area, not
just length. Do I have to find a steel shop for a core?

What kind of transformer? A mains transformer? A pulse transformer?
Audio Transformer? RF Transformer? Transformer core materials vary
widely depending on the application.

And what do you mean when you say "area"? Cross-Sectional area of the
core? Of the winding?

If you don't provide some details you won't get useful answers.
 
R

Rene Tschaggelar

Jan 1, 1970
0
Kevin said:
What can I use for a transformer core? I think I need a piece of steel
with a large area. The example that I have seen has a large area, not
just length. Do I have to find a steel shop for a core?

On the tracks of the anchestors ? Building an educational
transformer ?
Actually steel is very wrong. Beside some special transformer
alloys, pure iron without carbon or anything is the best.
A bit of silicon improves it though. And having the
crosssection made from sheets also improves.

Rene
 
M

Mac

Jan 1, 1970
0
What can I use for a transformer core? I think I need a piece of steel
with a large area. The example that I have seen has a large area, not
just length. Do I have to find a steel shop for a core?

Another important thing to consider is currents in the transformer. You
don't want them. This is why transformer cores are typically made from
many metal stampings which are glued together. The glue does not conduct
electricity, so electricity can't flow in the core in the direction of the
induced electric field gradient.

Mac
 
R

Robert Baer

Jan 1, 1970
0
Mac said:
Another important thing to consider is currents in the transformer. You
don't want them. This is why transformer cores are typically made from
many metal stampings which are glued together. The glue does not conduct
electricity, so electricity can't flow in the core in the direction of the
induced electric field gradient.

Mac

Sorry, it is *not* glue.
Varnish used to be the potting material of choice, but there are some
good plastics that can be used.
 
H

Harlan

Jan 1, 1970
0
Mac is right about the core having to be laminated or some form of
core designed to eliminate eddy currents.
Another important thing to consider is currents in the transformer. You
don't want them. This is why transformer cores are typically made from
many metal stampings which are glued together. The glue does not conduct
electricity, so electricity can't flow in the core in the direction of the
induced electric field gradient.

Kathy, This is a really neat project and there are so many things you
can do to make this and make it work with minimal headaces. This core
material will seem to be elusive with out a small study to what is
happening. I will be starting a thread soon on designing a transformer
from old parts here real soon. The eddy currents would cause the core
to get hot, and heat destroys the magnetism and that stops the current
from transfering and the primary current then goes real high and then
you have smoke everywhere. Eddy is a bad thing!
You can actually get good core material by scrapping out an old
transformer, and is a great way to recycle materials that get thrown
away needlessly. The Iron in a transformer is the most expensive part,
and salvaging one for a project is great. I would recommend reading a
little on Volt Amp characteristics to make sure you get a core of the
right size for you project. Depending on the load current, (total VA)
something like an old ballast core may work fine too. And here all you
have to do is cut the old wiring away, salvage the laminations and
clean things up, make a new bobbin and wind the transformer to your
own design. There is a LOT of information on the net to help with as
well.
Just a thought here.
Good luck
Harlan
 
K

Kevin Weddle

Jan 1, 1970
0
Robert Baer said:
Sorry, it is *not* glue.
Varnish used to be the potting material of choice, but there are some
good plastics that can be used.

Okay. This is a power autotransformer. The core that I need then would
be just iron and not steel. I'm not going to glue or strip apart a
transformer. I can't measure the inductance, but I can calculate it.
This means that I'm sure that I will have inductance. The question is,
how good will it be.
 
B

Boris Mohar

Jan 1, 1970
0
Okay. This is a power autotransformer. The core that I need then would
be just iron and not steel. I'm not going to glue or strip apart a
transformer. I can't measure the inductance, but I can calculate it.
This means that I'm sure that I will have inductance. The question is,
how good will it be.

It will be crap. Look up eddy currents to start with. Get a junk microwave
oven and take out the transformer. The secondary is wound separately from
the primary. Hack out the secondary and wind your own.
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Kevin Weddle
Okay. This is a power autotransformer. The core that I need then would
be just iron and not steel. I'm not going to glue or strip apart a
transformer. I can't measure the inductance, but I can calculate it.

I very much doubt it.
This means that I'm sure that I will have inductance. The question is,
how good will it be.

Starting from where you are at present, good will not be the right word.
 
D

Don Lancaster

Jan 1, 1970
0
Kevin said:
Okay. This is a power autotransformer. The core that I need then would
be just iron and not steel. I'm not going to glue or strip apart a
transformer. I can't measure the inductance, but I can calculate it.
This means that I'm sure that I will have inductance. The question is,
how good will it be.

You are very unlikely to have inductance since a lousy choice of core
material will saturate.
What you have instead is called an "induction heater".

Using ~anything~ except a properly laminated and rated core material for
the frequency and flux density of interest will almost certainly burn up
at any reasonable power level.

--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com
 
R

Robert Baer

Jan 1, 1970
0
Kevin said:
Okay. This is a power autotransformer. The core that I need then would
be just iron and not steel. I'm not going to glue or strip apart a
transformer. I can't measure the inductance, but I can calculate it.
This means that I'm sure that I will have inductance. The question is,
how good will it be.

In short, you do not know what you are doing and have almost no clue.
 
S

Stefan Heinzmann

Jan 1, 1970
0
Kevin said:
Okay. This is a power autotransformer. The core that I need then would
be just iron and not steel. I'm not going to glue or strip apart a
transformer. I can't measure the inductance, but I can calculate it.
This means that I'm sure that I will have inductance. The question is,
how good will it be.

You can calculate the inductance? Pray show us how! I would be
interested in the formulas (formulae?) you use.
 
M

Mac

Jan 1, 1970
0
Sorry, it is *not* glue.
Varnish used to be the potting material of choice, but there are some
good plastics that can be used.

Well, I was going to say "adhesive," but I was afraid that sounded too
technical. If I had to guess what they actually use nowadays, I would
guess that it was polyurethane, but I surely don't know.

Mac
 
M

Mac

Jan 1, 1970
0
Okay. This is a power autotransformer. The core that I need then would
be just iron and not steel. I'm not going to glue or strip apart a
transformer. I can't measure the inductance, but I can calculate it.
This means that I'm sure that I will have inductance. The question is,
how good will it be.


You might be able to use a bunch of strands of insulated iron wire for
your core. This would then be a toroidal core transformer. I've never done
anything like this, but I am pretty sure that you can get insulated iron
wire somewhere.

--Mac
 
R

Robert Baer

Jan 1, 1970
0
Mac said:
Well, I was going to say "adhesive," but I was afraid that sounded too
technical. If I had to guess what they actually use nowadays, I would
guess that it was polyurethane, but I surely don't know.

Mac

I would guess that as well, or a close "relative".
 
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