Re: Core Material

To: tesla-at-poodle.pupman-dot-com
Subject: Re: Core Material
From: Tesla List <tesla-at-stic-dot-net>
Date: Sat, 03 May 1997 01:47:31 -0500
Approved: tesla-at-stic-dot-net
Subject:   Re: Core Material
  Date:    Fri, 2 May 1997 12:21:13 -0400 (EDT)
  From:    Esondrmn-at-aol-dot-com
    To:    tesla-at-pupman-dot-com, tesla-at-poodle.pupman-dot-com


In a message dated 97-05-01 18:20:51 EDT, tesla-at-pupman-dot-com writes:

<< 
 Hello Coilers,
 
 I am about to start building the secondary of my first (small coil), I
 have 
 some Acrylic rod and thought of using this for the former.  Being soild
 I 
 would be able to screw and bolt connections to the former.  I would
 think 
 losses would go up slightly as opposed to sealed tube construction but
 not 
 enough to be a problem.  Would there be any other problems using a
solid 
 plastic core?
 
 Also, I was thinking about half wave coils, not many people seem to
 build 
 these.  Why is this?  
 
 I look forward to receiving your replies.
 
 
 Rob Davis (UK)
  >>
Rob,

I would think a secondary of 2.0" to 3.0" in diameter would be a good
place
to start.  I did not know that solid acrylic rods were made that thick. 
It
should work ok, but as you seem to understand, thin wall materials will
have
the lowest loss.

Regarding half wave coils, if you set up a one half wave coil in the
traditional manner, with the bottom end grounded and a toroid on the
top, the
maximum voltage will still be generated at the one quarter wave point
which
will be half way up the coil.  i.e. the sparks will leave from the mid
point
of the coil.  A quarter wave resonant Tesla coil will produce the
maximum
current at the grounded end and maximum voltage at the top.  Half wave
coils
can be built (usually called a bi-polar coil) with the primary placed in
the
center of the coil.  Then high voltage is developed at each end.  The
usually
mounting is horizontal with raised terminals coming up from each end. 
The
sparks will travel between the terminals.

Ed Sonderman