Re: TC knowledge

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Mddeming-at-aol-dot-com>

In a message dated 1/8/02 11:42:39 PM Eastern Standard Time, tesla-at-pupman-dot-com
writes:


>
> Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <rheidlebaugh-at-zialink-dot-com>
>
> What you have said is correct. I stated a simple ideal view of a coil.
> Losses are a real life factor, but what point of your explanation is of any
> value to a child wanting to know why a TC works.
>    Robert  H 



Hi Finn, Robert, All,
       I have to agree with Finn on this one. What you have said about the
turns ratio is the way an iron-core low frequency transformer works, but it is
not how a Tesla Coil works. This is a misconception that has been propagated
for decades by "simple explanations." As Mark Zamansky said in the preface to
his classic work, Heat and Thermodynamics, "You can make the subject much
simpler to teach just by making it wrong."
       I think Finn's quantitative explanation could be made suitable for
children just by saying qualitatively that "Little spurts of energy are
transferred to the secondary and stored in the topload until they build up
enough to arc." This I believe is both understandable and more physically
accurate without getting into resonance etc.

Matt D.


>
> > From: "Tesla list" <tesla-at-pupman-dot-com>
> > Date: Tue, 08 Jan 2002 17:24:57 -0700
> > To: tesla-at-pupman-dot-com
> > Subject: Re: TC knowledge
> > Resent-From: tesla-at-pupman-dot-com
> > Resent-Date: Tue, 8 Jan 2002 17:46:42 -0700
> > 
> > Original poster: "Finn Hammer by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> > <f-hammer-at-post5.tele.dk>
> > 
> > Robert, all!
> > 
> > While it is true that a tesla coil is a transformer, it is not true that
> > it responds in a turns ratio fasion, when operating in disruptive mode.
> > Loose coupled coils take time to transfer the energy from one coil to
> > the other, and the amount of oscillations that it takes to transfer the
> > energy is determined by the coupling factor. With the coupling factors
> > that are typically involved in tesla coiling (0.1-0.2) it takes from
> > 8-16 cycles to make a full transfer from primary to secondary.
> > With regard to top voltage, this is a question of how much energy that
> > ends up in the toroid.
> > Let`s say that the primary capacitor is 50nF and that it is charged to
> > 20kV at the time where the sparkgap breaks down and starts conducting.
> > It then holds a charge of Epri=(Vpri^2)*Cpri/2 =
> > 20000*20000*0.0000005/2=10joule.
> > When this charge is transferred to the top terminal, the resulting
> > voltage is:
> > Vtop=sqrt(2*Epri/Ctop) For a top capacity of, say, 40 Pico Farads the
> > max. voltage will be:707106 volts.
> > 
> > This is not an impossible value, provided that the secondary coil is
> > long enough to hold off the voltage, the toroid is smooth enough, and
> > has a minor diametre large enough to prevent breakout at less than
> > that,and assuming a lossless gap. (and ignoring coil self capacitance)
> > 
> > Let`s not get carried away with unrealistic claims of multi million
> > volts on the top terminal, only a few coils exceed 1 million volts.
> > 
> > Cheers, Finn Hammer
> > 
> > Tesla list wrote:
> >> 
> >> Original poster: "rheidlebaugh by way of Terry Fritz
> > <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>
> >> 
> >> A TC is a special transformer. In a transformer when you put a voltage in
> >> the primary the voltage will be the same out as the ratio of turns. If you
> >> have 10 turns in the primary and 100 turns in the secondary the output
> >> voltage will be 10 times larger. Most TC coils have about 1: 100 turns.
> The
> >> voltage in is about 20'000v so the output can be 2,000,000V. No this is
> not
> >> all, but it is a over view of how it works. My small class room TC starts
> >> with 100V and puts out 10,000V.
> >> Robert  H