[Prev][Next][Index][Thread]

Re: Transformer cores

On Wed, 11 Nov 1998 09:05:47 -0700 In the Tesla List
Gregory R. Hunter <ghunter-at-enterprise-dot-net> wrote:

>Alfred & Max,
>
>I've often wondered about "transformer iron" as well.  I think it 
>contains lots of Silicon.  It magnetizes very easily in the presence of
a 
>magnetic field, but demagnetizes quickly when that field is removed--for
low
>hysteresis loss.

That is what I understand, in fact some of the newer transformer irons
have soo
much silicon they seem more like glass than iron.

>Many kinds of cheap wire made of poor quality, high silicon steel might
approximate >transformer iron.  I'm thinking of Alfred's concrete
reinforcing wire, galvanized fence wire, coat hanger wire, florists'
wire, etc.

I don't know about the high silicon, all the iron you mentioned has no
silicon in it what so ever. BUT I have made many transformers and
induction coils using the materials you mentioned. I knew an old timer
back in the 60's that made reproduction induction coils and Rumkorff
coils and he introduced me to the use of florist's wire and coat hangers.
The
florist's wire is better because it contains less carbon (carbon hardens
iron) and is of smaller diameter. I tried the concrete reinforcement wire
because spools of florist's wire was getting very expensive! I found the
concrete reinforcement wire to be almost as good as the florist's wire!

>I also understand about annealing the wire to make it softer, to reduce
hysteresis >losses, but is this strictly necessary?  How much loss are we
talking about if the core >material retains a bit of residual magnetism?

I cant say from an efficiency point but I can share my experience with
making induction coils. I made two induction coils as an experiment to
see in the annealing is really necessary and found it makes a BIG
difference! I made two induction coils of about 1 foot in length, one  I
annealed the wire for the core and on the other I didn't anneal the wire.
The result was that the coil with the annealed wire produced 8 to 10 inch
sparks where as the coil with the un-annealed core barely produced 3 inch
sparks and heated up very quickly in use. I allowed both coils to run
continuous and after about 4 hours the coil with the un annealed core
burned out from over heating while it's brother with the annealed core
was just purring along and was barely warm to the touch!

Another thing you should realize about annealing your iron wire, which is
if you don't protect the wire from the hot coals the wire will get carbon
incorporated in it's surface which will harden it and defeat the whole
purpose of annealing it! I learned to put the bundle of wires in a pipe
with a cap screwed on one end and the open end elevated above the coals.
After the pipe and wires start to glow you use pliers and gloves to cap
the open end of the pipe and push the whole deal under the coals (if you
try caping the pipe before this it may form a pipe bomb due to expanding
air inside). It is then important to allow the pipe and wires to cool
very slowly.

                               Alfred A. Skrocki
                          Alfred.Skrocki.Sr-at-JUNO-dot-com
                 Visit my Do-It-Yourself Aquarium WEB page at:
                  http://WWW.GeoCities-dot-com/CapeCanaveral/6251

___________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno-dot-com/getjuno.html
or call Juno at (800) 654-JUNO [654-5866]