RE: Fwd: [jlnlabs] TESLA COIL REVISED6

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

Original poster: "C. Kollett" <ckollett-at-falconaerosystems-dot-com> 

Hi,
Although I am a newcomer to the list, I respectfully disagree that several
hundred turn secondaries reduce the gain. I built a 20" dia x 48" L coil
with about 560 turns of 20G Teflon covered wire. Resistance was only a few
ohms, compared to the inductive reactance which is quite high. One of the
equations for Q is "Q = X(subL)/R".  If for example the inductive reactance
is 1K ohms and R is only a few ohms you will have a very high Q like 200! In
my opinion Q is what its all about along with a lot of drive power rich in
harmonics.
A Tesla secondary impedance could be complex in that it is a lumped
distribution of inductance and capacitance. However at resonance the total
reactance is highest and it is the point where capacitive inductance equals
inductive reactance.

Also for what its worth (maybe nothing at all!) Has anyone tried an
additional resonant coil (or coils) coupled loosly in the proximity of a
running coil which "should" add to the overall Q due to mutual inductive
coupling(i.e. multiple tuned circuits interacting with one another). Im not
an expert coil builder but I do have some experience building a fairly large
coil and have worked in electronic most of my life.

Rgds
to all

C.K



-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Friday, January 02, 2004 12:48 PM
To: tesla-at-pupman-dot-com
Subject: Re: Fwd: [jlnlabs] TESLA COIL REVISED6


Original poster: Tom Stathes <newphreak_16-at-yahoo-dot-com>


--- Tesla list <tesla-at-pupman-dot-com> wrote:
  > Original poster: Terry Fritz
  > <teslalist-at-twfpowerelectronics-dot-com>
  >
  > Hi,
  >
  > I am not sure who the original writer is, but...
  >
  > At 07:48 AM 12/30/2003, you wrote:
  >
  > >Note: forwarded message attached.
  > >
  > >
  > >__________________________________
  > >Date: Sat, 27 Dec 2003 06:54:13 -0800
  > >Subject: [jlnlabs] TESLA COIL REVISED
  > >Reply-To: jlnlabs-at-yahoogroups-dot-com
  > >Content-Type: multipart/alternative;
  > >
  > boundary="7sXqLKCsjnyYoY64pxfTPFI2R0ZhKSZJleFSmA1"
  > >Content-Length: 1751
  > >
  > >I have a problem with today's Tesla coils. The way
  > they're built these
  > >days, is with the secondary made with SEVERAL
  > HUNDRED turns of thin
  > >wire, which is WRONG. When Nikola Tesla made his
  > coils, they only had
  > >50 to 100 turns of a THICK wire as the secondary.
  >
  > Tesla used a three coil system while most of today's
  > Tesla coil builder's
  > use two coil systems.  They are considerably
  > different machines made for
  > different environments.  However, the basic
  > principles are the same.
  >
  >
  > >The problem with hundreds of turns of a thin wire
  > is that they have
  > >many times bigger resistance than Tesla's original
  > coils. This big
  > >resistance increases losses, and so minimizes
  > voltage increase due to
  > >resonance. Thick secondary wire will have small
  > losses which allows the
  > >resonance to build higher voltages.
  >
  > Due to the high voltage, the resistance loss in the
  > secondary is small and
  > not a major energy loss.
  >
  >
  > >Here's how Tesla's Colorado Springs coil was built.
  > Primary were 2
  > >turns of a thick cable, and secondary 100 turns of
  > No. 8 wire with a
  > >diameter of 51 feet. That's 1:50 ratio between
  > primary and secondary.
  > >Input was 50 kV into a .004 mF capacitor which was
  > connected to the
  > >primary coil through a spark gap. It could resonate
  > at frequencies from
  > >45 to 150kHz.
  >
  > His think secondary actually had 17 turns of wire.
  > He had a third coil 12
  > high 6 feet diameter 160 turns of #10.  It was a
  > magnifier with a modern
  > example at:
  >
  > http://www.ttr-dot-com/model13.html
  >
  >
  > >Tesla's power-transmission coil patent shows almost
  > the same coil,
  > >except that the diameter was 8 feet, and secondary
  > was wound as a flat
  > >coil (also no. 8 wire), and resonance was around
  > 250kHz, producing 2 to
  > >4 million volts.
  > >
  > >So if Tesla's coil could be reduced from 51' diam.
  > to 8' diam., while
  > >keeping the 1:50 primary/secondary ratio, then it
  > should be no problem
  > >to reduce that coil further to about 1' diameter,
  > using only 50 turns
  > >of a thick wire as a secondary.
  > >
  > >The only problem would be the 50kV input that Tesla
  > used, but even
  > >using only 5kV from a neon transformer should
  > produce 200 to 400kV
  > >using the 1:50 ratio, since 50kV input produced 2-4
  > million volts.
  >
  > See the above model 13 details at www.ttr-dot-com.
  >
  >
  > >Also, using a 1' diam. secondary will reduce its
  > inductance, which
  > >will increase resonant frequency to several MHz.
  > And using a very thick
  > >wire, copper pipe or Litz wire would be needed to
  > reduce high frequency
  > >losses.
  > >
  > >So, using a 1-turn primary and 50-turn secondary on
  > a 1-foot diameter
  > >air-core, should make a TRUE Tesla coil which will
  > have lower losses
  > >and more powerful resonance than today's "Tesla
  > coils". Plus that makes
  > >it much easier to make than winding hundreds of
  > turns.
  >
  > Winding hundreds of turns is not that hard ;-)  But
  > most of the losses
  > (40%) go into the spark at the gap.  The other
  > system losses due to coil
  > heating and cap losses are very small compared to
  > the spark gap.  "Modern"
  > Tesla coils are optimized for spark length given
  > commonly available input
  > power and size requirements.
  >
  > Of course, if one can make a better Tesla coil, just
  > do it!!! :-))
  >
  > Cheers,
  >
  >          Terry
  >
  >
  >
  > >Jaro
  >
  >