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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:
> <<
> > Robert & All:
>
> > Sometimes being slow/patient might be a benefit. Your post is of great
> >interest to me, specifically in how it relates to what I observed with
> > the coil design by Resonance Research, Inc. or D.C. Cox. The last few
> > weeks I have been considering whether that big toroid I mentioned in
> > early December would ever be built. Seeing that 19" dia by 39" wound
> > length coil spit out sparks in the 12 foot range with a 30" diameter
> > toroid has at least made me think there is at least two ways to skin
> > that poor abused cat!
> > No Robert, I haven't even purchased the material yet for the toroid.
> >It was planned for the end of this month or early February. I was
> > planning to start up the new coil with my present 8" x 48" toroid and
> > get things roughed in and then switch to a bigger toroid--now I might
> >change those plans somewhat. My present coil, 8" diameter by 28" wound
> > length using #20 wire ran with the 8"x48" toroid. The big difference in
> >performance between my coil and the Cox coil was I had 5'-7' sparks that
> >were not continuous. The Milwaukee Museum coil had continuous sparks
> >that reached out and just sorta happily sat there two or three at a
> >time, always one up to 12 feet long the others much smaller. They were
> > inside on a stage, I was out in the driveway with the normal 9:00 PM
> >summer night breeze. That pretty little spun aluminum toroid seemed to
> > be plenty for that coil, so your comments Robert, are hitting a target
> >over here by me. I already down-sized my cap, which I mentioned
> >yesterday, to .05 mfd-at-30KVAC, for two reasons, resonant frequency
> >dictated that was the perfect size, plus cost factors!
> > Hope the damage done to your secondary wasn't too bad. A couple of
> >questions on your coil--you mentioned the PVC coated #18 wire, I don't
> >recall if you have a layer of varnish over it or anything elsed? Most of
> >the standard hook up wire has about a 600 volt rating guess it wasn't
> > too hard for that MTC of yours to pop chunks like it did--would of
> >probably damaged any combination of materials under the cicumstances you
> > described.
>
> >snip
>
> > I have several photo's and I will post them when the primary is
> >completed. Any constructive criticism would be appreciated from all.
> > Tune for minimum smoke is always the goal.
> > Let us know about that "bigger toroid to stuff underneath"--maybe 30" x
> > 90"?? :-) Getting late here time to go to bed!
>
> >Chuck Curran
> >>
> 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 -
Bill's coil does deliver as stated. I have personally witnessed the coil in
operation (in fact, I have helped set it up on numerous occasions...) and the
15 footers are damned impressive. Nice and hot!
- Brent