Re: [jlnlabs] TESLA COIL REVISED

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

Original poster: "Trans-world" <jaro-at-surfside-dot-net> 

John,
Tesla was using only about 1:50 primary/secondary ratio in his coils,
because with 50 kV input he'd produce 2 to 4 MV on output of an 8'
diam. coil and that was enough for him. Producing higher voltage than
that would be increasingly difficult in a coil of that size because
voltages of 10 MV and higher would be hard to insulate.

So even with the 50-turn secondary that's 1 or 2 feet in diam., you
should have a plenty powerful Tesla coil with 50kV input, even though
the higher frequency might somehow reduce the spark length.

Also for practical purposes like communication, spark length should be
shorter rather than longer, because discharges  would cause unwanted
loss of power.

And since the L2/L1 ratio determines output voltage, it would be best
to use Litz wire in the primary loop, since decreasing L1 will increase
output voltage. I don't know if you guys are using it, but it could
clearly reduce the size of the secondary, or about triple the voltage
output of a 50-turn Tesla coil.

Jaro

-----Original Message-----
From: Tesla list <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Tuesday, December 30, 2003 7:38 PM
Subject: RE: [jlnlabs] TESLA COIL REVISED


 >Original poster: "John H. Couture" <couturejh-at-mgte-dot-com>
 >
 >
 >Jaro -
 >
 >Your type of question is good for Tesla coilers. These questions make
the
 >typical coilers review their understanding of how Tesla coils works.
What
 >you say is true that Tesla used coils with much fewer turns than
today's
 >TC's. Tesla was an engineer and obviously knew what he was doing. How
do you
 >explain this less turns from a theoretical standpoint?
 >
 >I believe the difference in the number of turns is partially explained
by
 >the fact that TC's relie on the flux linkages between the primary and
 >secondary coils.  Flux linkages are determined by ampere turns. In
other
 >words you can either have large amperes or large number of turns and
get the
 >same results. The problem, however, is that coilers normally ignore
flux
 >linkages in the design of their Tesla coils. They concentrate on other
TC
 >parameters that also affect the spark length like input power, losses,
 >secondary inductance, etc.
 >
 >A good example of coilers ignoring flux linkages is in the design of
the
 >primary coil. They will use small primary wire sizes and ignore the
high
 >primary currents that the primary must carry. Coilers hardly ever use
a
 >primary wire size that corrolates to the current carrying capacity of
the
 >wire size to the primary current during TC operation. In other words
if the
 >tuning of his TC requires only a few primary turns he will need a
larger
 >wire compared to a primary with many turns. Coilers seldom if ever
balance
 >the ampere turn parameter. Several years ago I was interested in this
design
 >problem and developed two graphs of recommended wire sizes, one for
the
 >primary and one for the secondary. The graphs are shown in my TC
Design
 >Manual. As for the secondary turns, an interesting fact about reducing
the
 >secondary turns is that the K factor is increased but that is another
story.
 >
 >Your one turn primary and 50 turn secondary would be OK except it
would be
 >ignoring the other parameters that affect the spark length. Even if
you had
 >the right primary and secondary wire sizes you would end up with a
shorter
 >output spark length. Tesla's coils took care of the other parameters
by
 >making the TC larger.
 >
 >John Couture.
 >
 >--------------------------------------
 >
 >
 >-----Original Message-----
 >From: Tesla list [mailto:tesla-at-pupman-dot-com]
 >Sent: Tuesday, December 30, 2003 1:01 PM
 >To: tesla-at-pupman-dot-com
 >Subject: Fwd: [jlnlabs] TESLA COIL REVISED
 >
 >
 >
 >__________________________________
 >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.
 >
 >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.
 >
 >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.
 >
 >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.
 >
 >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.
 >
 >Jaro
 >
 >