Fwd: [jlnlabs] TESLA COIL REVISED

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

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


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
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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