Re: [jlnlabs] TESLA COIL REVISED

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

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

You're right that higher inductance ratio will produce higher output
voltage, but it will also reduce resonant frequency. My proposed
50-turn secondary coil has at least 100 times lower resistance, and 35
times lower inductance than your 1000-turn coil. That results in MUCH
SMALLER resistance losses, and MUCH GREATER frequency and greater Q.

The point of Tesla coil isn't the highest voltage, but providing a
BRUSH-LIKE discharge. Otherwise it's just a fancy lightning generator.
And for that special discharge you need AT LEAST SEVERAL HUNDRED
kiloHertz frequency. And you can't get much more than about 100 kHz
from your high-inductance secondary coil. If you don't believe it,
here's what Tesla said about it:

http://www.pbs-dot-org/tesla/res/res_art05.html

Also, doesn't higher Q of a coil, translate into more powerful
resonance, and with it, HIGHER VOLTAGE? Remember that the lower the
resistance losses, the higher the voltage due to resonance will be.

And the problem with your "Output (gain) = Einput x sqr (Ls/Lp)"
equation is that it doesn't include the Q of the coil. It will be true
for two coils made with the same diameter wire, but NOT TRUE if the
coils are made using different wire gauges. That's because you can
increase wire thickness without increasing coil's inductance, and
thicker wire will output higher voltage because of higher Q, than your
equation would predict.

Jaro

-----Original Message-----
From: Tesla list <tesla-at-pupman-dot-com>
Date: Tuesday, December 30, 2003 7:37 PM
Subject: Re: [jlnlabs] TESLA COIL REVISED


 >Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>
 >
 >
 >Using several hundred turns of thin wire is the best way to construct
 >classic Tesla coils.  We use 1000 to 1,400 turns on most all of our
coils.
 >Tesla's coils were mostly magnifier designs and in these designs hi-Q
factor
 >for the "driver" coil is essential while the "resonator" coil does not
 >require hi-Q for maximum output.
 >
 >You need to balance the Q factor against the load impedance and
topload
 >capacitance and consider all three to determine best output
parameters.
 >
 >1,000 to 1,400 turns of wire works great with a large secondary toroid
 >usually 2 x the sec. coilform dia or more.  This design produces
optimum
 >output from classic coil designs.
 >
 >The large number of turns produces a high inductance ratio which is
critical
 >to achieving best output.  Q factor does not enter the equation for
classic
 >coil design but is very important in magnifier design such as Tesla
was
 >using on his Col. Springs coils.
 >
 >Output (gain) = Einput x sqr (Ls/Lp)        (classic coil)
 >
 >Dr. Resonance
 >
 >Resonance Research Corporation
 >E11870 Shadylane Rd.
 >Baraboo   WI   53913
 > >
 > > First you present a different idea and then labeled all the working
 > > coils as "Wrong". Have you tested your ideas and proven they work
as you
 > > expect? If so we'd all like to see the results as it could open up
a new
 > > area of coiling.
 > >
 > > Regards,
 > > Brian B (trying to keep an open mind)
 > >
 > > -----Original Message-----
 > > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 > > Sent: Tuesday, December 30, 2003 10:01 AM
 > > 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
 > >
 > >
 > >
 >
 >