Re: Modeling Secondary Inductance

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Jeff,

Well, if your an engineer and really can't help yourself, here is probably a
lot more than you wanted to know :-)))  It has kept me busy for a few years
;-))


Basically, the secondary coil is a complex mess that can be modeled
successfully with a coil capacitance (Medhurst capacitance) and a top load
capacitance.  It has now also been modeled in great detail using computer
analysis.  I could go on for hours but this will get you started on the subject
Richard Hull warns "will simply make you nuts" :o)

If you really want to know the nasty details (as many of us do :-))), see the
great work by Paul Nicholson:

http://www.abelian.demon.co.uk/tssp/

Especially:

http://www.abelian.demon.co.uk/tssp/pn2511.pdf.zip

Also a general paper of mine at:

http://hot-streamer-dot-com/TeslaCoils/MyPapers/modact/modact.html

I use MicroSim and have some coil models:

http://hot-streamer-dot-com/TeslaCoils/Programs/91pspstu.exe
(that one is 27mB!)
http://hot-streamer-dot-com/TeslaCoils/Programs/MicroSim/MicroSim.html
http://hot-streamer-dot-com/TeslaCoils/MyCoils/BigCoil/BigCoilSCH.gif
http://hot-streamer-dot-com/TeslaCoils/MyCoils/SmallCoil/SmallCoilSCH.gif

Also:

http://hot-streamer-dot-com/TeslaCoils/Programs/E-Tesla6.zip
http://hot-streamer-dot-com/andrewb/

Is a program that finds the resonant frequency (see the text files...)

More general info at:

http://hot-streamer-dot-com
http://hot-streamer-dot-com/TeslaCoils/TeslaCoils.htm

Cheers,

        Terry


At 05:28 PM 9/9/2001 -0600, you wrote: 
>
> Hi everyone,
> I was using WinTesla to design my coil and started playing with the Spice
> model provided.  A book I have (The Tesla Coil Book by Brent Turner)
> describes the secondary as a series resonant ckt but the Spice model from
> WinTesla shows the self capacitance plus the toroid cap in parallel.  This
> makes sense to me since self-capacitance comes from inter-winding and planar,
> both of which are in parallel with the coil inductance.  Is the book wrong or
> am I missing something?  Another point of confusion for me is how the
> secondary is treated both as a quarter-wave resonator and an LC resonator. 
> The first is a transmission line concept (i.e. distributed inductance and
> capacitance) while the second is a lumped element concept.  Is this like
> wave/particle duality of light or something?  
> Something else I noticed about the model was that when the spark gap switch
> closed, the coil output spiked up and rang down.  I thought the secondary
> oscillations built over successive firings until the voltage reached a
> threshold and blasted out sparks.  I read an analogy with lasers somewhere...
> Anyway, if some of you theoriticians out there wouldn't mind setting me
> straight on the concepts, I would be most grateful.  I am an engineer so I
> can't help having to know exactly how these things work!
> Thanks in advance
>  
> Jeff Johnson
> Salt Lake City