Re: [jlnlabs] TESLA COIL REVISED

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

Original poster: "RIAA/MPAA's Worst Nightmare" <mike.marcum-at-zoomtown-dot-com> 

Here's a link http://users.rcn-dot-com/laushaus/tesla/primary_resistance.htm
where several different primary inductor topologies and material
combinations were tested for gain/dc resistance/ac resistance, but at most
TC frequencies copper litz wire is actually one of the worst things to use
for a conductor and only gets worse as the frequency rises. I have yet to
reason why since it's meant for RF apps. I wouldn't have believed it if I
didn't see it.


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, January 02, 2004 2:49 PM
Subject: Re: [jlnlabs] TESLA COIL REVISED


 > 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
 >  >
 >  >
 >
 >
 >