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Re: Fwd: [jlnlabs] TESLA COIL REVISED6



Original poster: dhmccauley-at-spacecatlighting-dot-com 


By reducing the number of turns in your secondary, you are reducing the
inductance.  Maintaining a constant primary side of your coil, you will need
to increase
the topload of your secondary to maintain resonance.  Now since GAIN = SQRT
(C1/C2) it is fairly obvious that by increasing C2 you are decreasing the
maximum
theoretical gain of your secondary.

Dan


 > 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
 >   >
 >   >
 >
 >
 >
 >
 >