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

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