RE: Designing BIG Secondary Coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Dave,

On 6 Sep 2002, at 16:11, Tesla list wrote:

> Original poster: "Dave Hartwick by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <ddhartwick-at-earthlink-dot-net>
> 
> Malcom,
> What is the composition of that sewer pipe? You're not talking about terra
> cotta pipe, I assume?

Definitely not :)  It's some kind of PVC or such. Pretty heavy. I 
can't really be more specific than that as I simply don't know. I 
spotted the offcut in the back alley of a construction materials 
supply outfit.
 
> How are you accomplishing space winding?

Bifilar wind two lengths of the same gauge wire. Fix at both ends. 
Stand the coil upright, then let one of the lengths go. It neatly 
unwinds/unpeels itself to part-way down leaving the spaced wire 
intact. Some spray varnish applied to the exposed winding holds it, 
then you can snip another length and let it unravel. I ended up with 
a bundle of various lengths at the base of the coil, some of which I 
re-used for other projects. The ideal would be to unwind the spacing 
wire back onto a reel but great care would be needed not to disturb 
the wanted winding. 
     I am planning to wind two others, one 10", the other 12" 
sometime in the future using much the same techniques. This time they 
will be using thinwall pipe left over from a construction project at 
work.

Regards,
malcolm