Re: Toroid size on Big Coils

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>

Thanks for the clarification. You told me some time back, off list, of the
conservative power levels you recomended the M150 at. I think a coil this
big can be pushed much further, as you did the M200 at Cheeshead, resulting
in the damage. So, If I run it harder, I'll think about that larger toroid
design. Oh, how I wish I could run my coils that often.
----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Thursday, February 09, 2006 10:37 PM
Subject: Re: Toroid size on Big Coils


> Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
>
>
> We've used the x2 approach on all of our M-150s which run in museums
> 7 days per week --- one now for over 22 yrs with no flashovers.  I
> doubt you will ever use yours that much.
>
> x 3 and x 4 will produce high outputs, ie, allowing you to drive more
> power with larger caps into the system.
>
> Sorry if I confused the issues here.
>
> Dr. Resonance
>
>
>
> >Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>
> >
> >DC, you say the 36" diameter toroid is sufficient for an 18" sec. However
> >you say 3 to 4 times sec diameter is ideal. And you further state that
the
> >toroid on the M-200 was 48", thats nearly 2 1/2 times the sec diameter of
> >20". This is proportionally larger than mine. Why don't you think I'll
have
> >secondary strikes?
> >----- Original Message -----
> >From: "Tesla list" <tesla@xxxxxxxxxx>
> >To: <tesla@xxxxxxxxxx>
> >Sent: Wednesday, February 08, 2006 7:17 PM
> >Subject: Re: Toroid size on Big Coils
> >
> >
> > > Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
> > >
> > >
> > > Mike:
> > >
> > > If you use a 36 inch dia. toroid on a coil similar to my M-150
> > > design, which has 18 inch dia. sec coil, there will not be any toroid
> > > to coil strikes.
> > >
> > > I didn't have in stock a large enough toroid for the M-200 design
> > > that you saw get damaged.  We normally use a 60 inch x 20 inch toroid
> > > size on this coil and during the Cheesehead event we only used a 48 x
> > > 12 inch toroid which didn't offer enough electrostatic shielding for
> > > the sec coil.
> > >
> > > Good rule of thumb is to use 3-4 x dia. of sec coil for major toroid
> > > dia. and then you will not have any problems.  A 3:1 major to minor
> > > toroid dia. also gives the correct ratio for this toroid design ---
> > > either spun or mesh toroid --- makes no difference to the sparks.
> > >
> > > Email off-list and I can share a unique design for a chicken wire
> > > toroid like we had on the Big Bruiser that can be constructed for
> > > under $125 in sizes up to 6 ft. in dia.  Big Bruiser uses a 10 ft dia
> > > x 24 inch cross section for it's toroid.
> > >
> > > Dr. Resonance
> > >
> > >
> > > Subject: Toroid size on Big Coils
> > >
> > >
> > > >Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>
> > > >
> > > > From what I see on the profesional coiling sites, in particular KVA
> > > > effects, and Tesla Technology Research, the toroids seem small for
> > > > the size of the larger coils. I know the cost of large spun toroids
> > > > is prohibatively expensive. In the case of the M-13 magnifier, the
> > > > majority of pics, show the discharges comming off the corona ring
> > > > and not the toroid. With this coil, and Electrum, many of the arcs
> > > > seem to be hitting the secondary. At the Cheesehead teslathon this
> > > > past summer, the M-200 of D.C. Cox had several secondary strikes,
> > > > one of which severely damaged the sec. He said 'that's what happens
> > > > with too small of a toroid.  How does one avoid this kind of
> > > > catastrophic damage? I'm planning to make a coil similar to DC's
> > > > M-150. It uses an 18" form, and I have a 36" spun toroid. I don't
> > > > want to destroy my secondary.
> > > >
> > > >
> > >
> > >
> >