*To*: Futuret <futuret@xxxxxxx>, Tesla Coil Mailing List <tesla@xxxxxxxxxx>*Subject*: Re: [TCML] Tesla Coil parameters list like Tesla Map software (i.e. spark length, secondary height, # of NSTs)?*From*: Timothy Gilmore <tdg8934@xxxxxxxxx>*Date*: Tue, 7 Apr 2015 07:11:26 -0500*Delivered-to*: teslaarchive@xxxxxxxxxx*Delivered-to*: tesla@xxxxxxxxxx*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=7DPYIr20YSp8yaXCkxeaHImWvDMTq/LC0c0sJ6aWjKU=; b=sy2LjFTxFaayGftqBY6BeU8jGg4JuZBgKIaT2WhVE2uzqOrrQy2BC+rWBR9ahsrrTe m1wklizaRUxr7wbuHRNPyOqhgMaQ2cEfXAacQV4kk1CTyB/KiW7VyUBhntHzistoD2LS /aGviSLP4yobIpEnkYpaJGDC82b+fUtuTd5Vl8phPF4ApHmw2b4ulBdatvQXzOG8UDNn PQclMeqZD+yBPiB1zMn5YXz2J+T3/ErlqPzbTuTQUlgylt+7uPq8ZfxZK0NqkcQF5kQ0 Lbm/ujLpIE/EG9VPxPAYj3jq9QsDhFsy3eMRLDhYuaF4JSm5pnZ40cGJG4ojKEN0DBHS V4kA==*In-reply-to*: <14c918e0fe0-2d63-317dc@webprd-a34.mail.aol.com>*List-archive*: <http://www.pupman.com/pipermail/tesla/>*List-help*: <mailto:tesla-request@pupman.com?subject=help>*List-id*: Tesla Coil Mailing List <tesla.pupman.com>*List-post*: <mailto:tesla@pupman.com>*List-subscribe*: <http://www.pupman.com/mailman/listinfo/tesla>, <mailto:tesla-request@pupman.com?subject=subscribe>*List-unsubscribe*: <http://www.pupman.com/mailman/options/tesla>, <mailto:tesla-request@pupman.com?subject=unsubscribe>*References*: <CAL4hW5LyOYXAJgtSunvvsdwR5iwp3kQNR=FXH03HSZ3NiDdqNw@mail.gmail.com> <14c918e0fe0-2d63-317dc@webprd-a34.mail.aol.com>*Reply-to*: Tesla Coil Mailing List <tesla@xxxxxxxxxx>*Sender*: "Tesla" <tesla-bounces@xxxxxxxxxx>

John, I see what you mean with the formula 1.7 * sqrt NST power. I'm only getting about 50-65% of that meaning at 1850W I get 3-4' sparks and should get closer to 6' I am using a 20A 0-130vac variac that actual gives up to 145 vac measured. It is when I turn this up bast 120vac on the dial I get closer to 4' sparks - BUT then I'm blowing 20A fuses in the variac. Using your toroid formula: toroid diameter (inches) = 0.5*sqrt input power (watts) means with 1850W I should only use 21.5" and I have 6"x25" so that's close. However, If I move up to an 8" diameter aluminum dryer ducting (with 17.75" center) that will be almost 34". I keep reading Bigger is best but it sounds like it may not be here. Thoughts? Tim On Mon, Apr 6, 2015 at 8:45 PM, Futuret via Tesla <tesla@xxxxxxxxxx> wrote: > I use the formula: > > spark length (inches) = 1.7*sqrt input power (watts) > > For example a coil that uses 1000 watts should > produce a 53.7" spark. However this formula only > works for very efficient coils. To get this sort of > efficiency it's usually necessary to use a synch > rotary spark gap at 120 bps, and a suitable LTR > sized capacitor (for NST systems). Such a coil > would work well with a 16" toroid. Toroid size tracks > with spark length as given by the formula. > Figure the toroid diameter should > be about 0.3 times the calculated spark > length. Or use the formula: > > toroid diameter (inches) = 0.5*sqrt input power (watts) > > Note that my formula uses a square rule for > spark length vs. power input. The older idea > of using a more linear relationship probably > came about because many small old coils > tended to be inefficient and therefore gave a > false impression. The toroid formula will > also only work right for an efficient coil. > > For example my TT-42 coil produces a > 42" spark from an old "robust" 12/30 NST. > The system draws about 800 Watts. The > formula suggests 48" sparks, but I only > get 42". However I have to crank up > the input power using a 140V output > variac to get the 42" spark, so the NST > is probably saturating some at that point, > and becoming less efficient. NST's can > draw a lot more than their rated power > in a Tesla coil running at 120bps. > Over-volting them also makes them > draw more power. > > Your 6" x 25" toroid should be able to > produce 80" sparks (assuming a > suitable Tesla coil design and power > input. I don't think going to an 8" > toroid will help your coil very much. > There must be something else > limiting your spark length. > > John > > > > > > > > -----Original Message----- > From: Timothy Gilmore <tdg8934@xxxxxxxxx> > To: Tesla Coil Mailing List <tesla@xxxxxxxxxx> > Sent: Mon, Apr 6, 2015 8:09 pm > Subject: Re: [TCML] Tesla Coil parameters list like Tesla Map software > (i.e. spark length, secondary height, # of NSTs)? > > > I found Jeff Pennoyer's > site: > > http://www.webring.org/l/rd?ring=teslaring;id=107;url=http%3A%2F%2Fhome%2Ecomcast%2Enet%2F%7Epennoyer%2FJeffPage%2Ehtml > > At > the bottom there is this list which falls in line with what I was > looking for > on spark length: > > APPROXIMATE SPARK LENGTH VRS POWER INPUT CHART > SPARK LENGTH > POWER INPUT > 6 - 8 INCHES 300 W > 8 - 12 INCHES 500 W > 12 - 18 INCHES 700 W > 15 - > 20 INCHES 1000 W > 18 - 24 INCHES 1200 W > 24 - 30 INCHES 1500 W > 30 - 36 INCHES > 2000 W > 36 - 45 INCHES 2500 W > 45 - 56 INCHES 3000 W > 56 - 64 INCHES 3500 W > 64 > - 72 INCHES 4000 W > 72 - 80 INCHES 4500 W > 80 - 90 INCHES 5000 W > > So using (2) > 15kv 60mA NST provides about 1850 W. I am getting at least 36 > inches and many > times 48 inches or more of sparks from my 6"x25" toroid: > > > > _______________________________________________ > Tesla mailing list > Tesla@xxxxxxxxxx > http://www.pupman.com/mailman/listinfo/tesla > _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla

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