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Re: Spice simulation pictures
Tesla List wrote:
>
> > > Subject: Re: Spice simulation pictures
> > Subject: Re: Spice simulation pictures
> > > Subject: Re: Spice simulation pictures
>
> >From hullr-at-whitlock-dot-comMon Oct 14 21:17:14 1996
> Date: Mon, 14 Oct 1996 12:44:16 -0700
> From: Richard Hull <hullr-at-whitlock-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Spice simulation pictures
>
> Tesla List wrote:
> >
> > > Subject: Re: Spice simulation pictures
> >
> > >From sgreiner-at-mail.wwnet-dot-comSun Oct 13 22:22:02 1996
> > Date: Sun, 13 Oct 1996 09:56:45 -0700
> > From: Skip Greiner <sgreiner-at-mail.wwnet-dot-com>
> > To: tesla-at-pupman-dot-com
> > Subject: Re: Spice simulation pictures
> >
> > Tesla List wrote:
> > >
> > > >From lod-at-pacbell-dot-netWed Oct 9 22:54:10 1996
> > > Date: Mon, 09 Oct 1995 21:26:28 +0000
> > > From: GE Leyh <lod-at-pacbell-dot-net>
> > > To: tesla-at-pupman-dot-com
> > > Subject: Re: Spice simulation pictures
> > >
> > > Dave Huffman wrote:
> > >
> > > If you visit ftp://d0huff.fnal.gov/ftp you should find the JPGs
> > > > along with the spice demo I used. The schematic/spice file is there
> > >
> > > Nice simulations! I was wondering if you have tried to more closely
> > > model the secondary coil, that is to represent the self-capacitance
> > > as distributed along the secondary rather than as lumped at the end.
> > >
> > > I've been playing around with PSPICE, and I think that I might have
> > > an explanation for why larger toroids yield better output. This
> > > effect has been observed empirically by many coilers, including the
> > > folks at the TCBOR, and has confounded me for quite some time, since
> > > if you add capacitance to the output the voltage there must decrease,
> > > if energy is to be conserved.
> > > As it turns out, a Tesla Coil will only act like a resonant xfmr if
> > > the sec capacitance is concentrated at the top, just like in your
> > > PSPICE model. By contrast, if you distribute the capacitance evenly
> > > over the sec coil then it starts to behave as a tapered transmission
> > > line, which produces less output. A tapered xmsn line is not as good
> > > because it always stores at least part of its energy in the magnetic
> > > field, and so never at any instant in time is all of its energy
> > > present solely in the electric field, where it would produce output
> > > voltage. So by adding more and more capacitance to the top, the
> > > currents at all points along the coil are brought into phase,
> > > yielding the best output voltage. More C past this point should
> > > start to degrade performance.
> > > How much C is optimum? Still working on that one, but it's probably
> > > more than an 'proportionally sized' toroid would provide.
> > >
> > > -GL
> >
> > Greg
> > This discussion seems to infer that the length of the TC when using the
> > transmission line analogy is something other than 1/4 wave long. My
> > understanding of transmission lines is that he energy transmitted down
> > the line continously transfers between the magnetic field and the e
> > field. If the TC secondary is indeed 1/4 wave long then it appears to me
> > that it would certainly be possible to have all of the energy in the
> > transmission line concentrated at the top of the secondary in the
> > e-field without the need for a large toroidal capacitance. A previous
> > discussion has touched on the need for a physically large discharge
> > discharge electrode to prevent premature breakout so I won't go into
> > that here, but if a way could be found to make a true 1/4 wave secondary
> > without the need of a toroid to tune it AND a way to prevent premature
> > breakout without a large electrode our TCs might end up looking entirely
> > different.
> >
> > Comments and flames, please
> > Skip
>
> Skip,
>
> Once again, take a coil, any coil, with or without terminal capacitance.
> Ground the base. Shock excite it. It will with out fail resonate at
> its natural 1/4 wave frequency.
IS this frequency the quarter wave of the wire length or what?
No tuning is required with terminal or
> anything! It is unavoidable and impossible for the resonator system to
> due otherwise! Also the maximum voltage point will always be at the top
> of the system, provided that you are not dragging the system to another
> frequency by forcing in huge amounts of mistuned, coupled energy via a
> magnetic or direct coupled source. If the shock excitement is tuned to
> the same frequency as the resonator, then we are really cookin'.
>
> The addition of a toroid is never, ever needed to TUNE a resonator,
> unless the primary tap and input capacitor are cast into an epoxy block
> and will forever remain invariant. The addition of a terminal will
> always detune or change the RESONAOTR SYSTEM'S natural period of
> oscillation. A complete Tesla coil system can be tuned by varying any
> ONE of the following, provided all the other components are set in stone
> and are forever invariant.
>
> 1. Change the input capacitor,
> 2. Change the primary inductance,
> 3. Change the resonator coil in any way,
> 4. Change the terminal capacitance.
>
> Under no circustances will a quarter wave transmission line with a coil
> in it, anywhere, ever equal a wire path length of 1/4 wavelength. Only a
> rigid piece of straight conductor floating in the vacuum of outer space
> has any chance of approaching this value.
>
> Richard Hull, TCBOR
Richard and All
Thanks Richard. I accept what you say except as noted above.
I don't wish to belabor this and I will shut up after this
comment/question.
I have been unable to excite any coil in any fashion and cause it to
resonate at a frequency equal to the 1/4 wave length frequency of the
wire of which it is wound. If anyone has I would appreciate hearing the
dimensions of the device.
Skip