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Re: Toroid Size?
Tesla List wrote:
>
> Subscriber: FutureT-at-aol-dot-com Wed Jan 8 22:53:27 1997
> Date: Wed, 8 Jan 1997 21:48:39 -0500 (EST)
> From: FutureT-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Re: Toroid Size?
>
> In a message dated 97-01-08 02:52:55 EST, you write:
> Chuck,
>
> I read with interest your descriptions of your work and of the DC Cox coil.
> The smaller Cox coil here in NJ gives similar but shorter "hanging in the
> air for awhile" type sparks. My only suggestion for your project is; make it
> modular so anything and everything can be easily and quickly changed, this
> way you can find out what works best, by trial and error. A lot of work, but
> there's no substitute.
>
> BTW, I have here a back issue of TCBA News from 1984, vol. 3, # 2. There's
> an article starting on page 11, by DC Cox concerning coefficient of coupling.
> Cox mentions in the article that his model 150 Tesla coil, which uses a
> secondary winding length of only 34", draws 5.5 kW and produces 13' sparks.
> There happens to be an article by Bill Wysock in the same issue. Here's
> the specs on Bill's Model Nine Tesla coil; pri. is 4 (?) turns of .375"
> copper tubing, sec. form is 21" dia. x 60", 1/4" thick phenolic, the wire is
> mil-spec mylar-jacketed thick-wall PVC insulated #16 AWG stranded silver
> plated copper, 560 turns. Ten coats of shellac are applied in a controlled
> environment. Toroid is 30" dia, polished, with 8" cross section. Capacitor
> is 0.1 uF. (polypropylene). The 1800 rpm synchronous rotary has 0.50" dia.
> tungsten electrodes. Bill claims that using no more than 5 kW, it produces
> in excess of 15" sparks.
>
> Good luck with your system!
>
> Happy and effective coiling,
>
> John Freau
John:
I appreciate your comments and suggestions. The phrase you used "make
it
modular so anything and everything can be easily and quickly changed" is
really the basis for this entire project. I've selected construction
features that will first allow me to move the thing around in sections
with ease(all but the secondary and it's weight!). One big change from
coil #3 to this #4 coil is the primary support structure. It's
basically an open bottom so tuning taps can reach any point on the
primary. The sides are vertical boards, so that the assembly looks sort
of like a square dresser drawer with no bottom. across the open bottom
are the wooden pieces for the acrylic coil supports. They are
positioned so that the coil is actually 1" down inside, so it will be
protected during movement. The strike rail will be removeable and
installed when run. Basically 90% of the area beneath the primary is
open down towards the area where the spark gap system and cap will be.
I will be using 3 or 4 inch PVC legs on this thing that are going to be
sized in length to position the primary for proper coupling with the
secondary. Bert Hickman has desribed several times a very handy
technique (using LED's) for calculating the k that I will employ prior
to the first firing, targeting .22--we'll see what happens. It's been
alot of fun so far. All the sections will be relatively easy to modify,
if my wallet can keep up! There's a Hamfest this weekend about 25 miles
from here, plan to head out there too. I've already got two Tek 531
scopes, maybe a third? :-)
Chuck Curran