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

Re: WIRE CHART


Subject:       WIRE CHART

>From brad.alheim-at-the-spa-dot-com Wed Mar 27 08:44 MST 1996
>Date: Wed, 27 Mar 96 10:15:49
>Subject: WIRE CHART
>To: tesla-at-grendel.objinc-dot-com
>
>
>Hello Richard,
>Again, thanks for your time and excellent answers! I look forward
>to reading your posts, you could write THE book on building coils!
>I'll start winding as soon as I get my wife's car (another project!)
>cleared out of the garage.
>
> Would there be any advantage of using a honeycomb wound copper
> tubing primary over a flat or saucer shape? (other than it
> would look purdy :)
>
R>> I am not sure what you are referring to. Please expound a bit.
>
>I am not good at "ascii art", so I'll try to explain what I mean:
>If you could take a board and put nails in it in a circle, driven
>in at right angles to the plane of the board so that it looks like
>a cage of vertical nails and then wind the turns in and out of the
>nails in sort-of-a solenoid fashion (an odd number of "nails" is
>needed so that every turn "crosses" the other and they do not lie
>directly over each other) This results in a coil with a low
>parasitic interwinding capacitance. Of course, the coil would be
>copper tubing and the "nails" steel pipe screwed into floor flanges
>on a piece of 3/4" plywood. (The pipe form is removed after winding!)
>This type of coil was used in "ancient" (1906-1925) radios before
>the advent of mass produced machine made windings, and I've seen
>them used with tubing in a couple of pictures of spark transmitters.
>Of course, like many of the "ancient" methods, there may be no
>merit in doing it this way. I hope that my "explaination" is OK!
>
>Thanks again,
>Brad Alheim


Hello Group,

I'd like to jump in here and put in  my 2 cents worth.  This actually
costs me about 2.8 cents in my quaint Canadian money.  I think I understand
the
physical geometry of the coil winding technique
which Brad Alheim is attempting to describe, and I'd like to suggest that
where it's merit might best be used to advantage, that is to say as Brad
points out,
it has reduced interturn capacitance, might be a good way to wind a
high performance SECONDARY coil! This is where interturn capacitance
is really a problem to performance.  You have to charge this built-
in distributed capacitance every time you send a power pulse up your 1/4
wave helical resonator.  Less capacitance here from a different winding
technique
and  subsequent reductions in the interturn capacitance from
dielectric protective coatings, the coil form, etc.,  would let more energy
arrive at the top where we want it!   This is one way (I suspect) where coil
length to diameter aspect ratio can contribute a  very real  yet not
commonly understood influence to coil performance.
Congratulations Brad for inspiring thought in this direction!

The down side to this idea however (if I've got Brad's concept
visualized correctly),  is the mechanical reality of
winding thousands of feet of wire onto such a specifically convoluted form
with a continuous and repetitious hassle of every second post being in the 
way
that you need to get your supply reel of wire around.   In a factory
a machine could be made to do this through the economy of mass
production.  In the home workshop this might be a good example of
'diminishing returns'.  A thousand times the effort for a 5%(?) gain?

Comments anyone?

Happy coiling, R.W.S.