# RE: [TCML] Toroid question

```Yes, there surely is a topload size that's too large for every coil.  Unfortunately no one has yet discovered a means of predicting what that size is, so all we have is some very crude rules of thumb and trial and error.

When a top load is too large, it doesn't just make the sparks smaller; it's an all or nothing proposition.  Beyond a certain size, the topload simply won't break out - even with a breakout point.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of Dex Dexter
> Sent: Saturday, May 30, 2009 3:13 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Toroid question
>
> Spark lenght = 1.7*SQRT(P)
> is P in watts power delivered to Tesla coil circuit or total power drawn from the
> mains?
> Also,I heard that you developed the formula on the basis of SRSG , 120 PPS,and
> equal bang sizes coils.
> Does that mean  it is not so accurate for static gap coils,ARSG coils,and higher
> PPS coils.
>
>
> Gary,there is surely a possiblity of a too big toroid for a power level.Let say ,if you
> put 48"x12" (with a braekout point on it) toroid on 360 W coil.That would probably
> decrease a spark lenght output,right?That size of the toroid is optimum for a 1 kW+
> range coil.
>
> Dex
>
> --- futuret@xxxxxxx wrote:
>
> From: futuret@xxxxxxx
> To: tesla@xxxxxxxxxx
> Cc:
> Subject: Re: [TCML] Toroid question
> Date: Fri, 29 May 2009 18:18:23 -0400
>
> Andrew,
>
> at my website, I show my TT-42 coil with a 4" x 13" spun toroid.  The
> coil
> produces 42" sparks using a robust 12/30 NST.  An ordinary 12/30 gives
>
>  http://futuret.110mb.com
>
> Cheers,
> John
>
>
> -----Original Message-----
> From: Lau, Gary <Gary.Lau@xxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Sent: Fri, 29 May 2009 9:13 am
> Subject: RE: [TCML] Toroid question
>
>
>
> Hi Andrew,
>
> As you noted, bigger toroid equals bigger streamers but fewer of them.
>
> Personally, between the two choices you gave, I would choose the larger
> 4.5x18
> toroid.  I haven't personally built a coil powered by a 12/30 so I
> can't say how
> much larger than that one could go.  Do you already own both of those
> toroids?
> If so, try stacking both of them and see how that performs, assuming
> that you
> have sufficient primary turns to accommodate the lower frequency.
>
> The final answer will depend upon how much time and cash you have
> available.
> Big spun toroids are expensive.  If cash is limited, you may want to
> try the
> http://www.laushaus.com/tesla/foamtoroid.htm
>
>
> Regards, Gary Lau
> MA, USA
>
> > -----Original Message-----
> > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> > Behalf Of Andrew Robinson
> > Sent: Friday, May 29, 2009 3:23 AM
> > To: tesla@xxxxxxxxxx
> > Subject: [TCML] Toroid question
> >
> > I asked this once before but dont remember getting a very clear
> >
> > With a 4" x aprox 22" secondary. 12/30 NST what would be an
> appropriate
> > sized toroid? I've heard bigger toroid equals bigger streamers but
> fewer
> > of them. I guess looking at it from the physics point of view, bigger
> > toroid = more capacitance = bigger streamer but longer charge times.
> >
> > Basically we're looking at either a 3" x 12" spun toroid or a 4.5" x
> 18"
> > spun toroid. Also is there a better place to get these other than
> ebay.
> > Can someone out there sell us one?
>
>
>
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