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RE: Primary construction



Original poster: "John H. Couture" <couturejh-at-mgte-dot-com> 

MCP -

The parameters for a .375 sec radius TC are:

Pri - 2.5 rad - 3.5 hg

Pri Cap - .006 uf

Sec - .375 rad - 10.5 hg - 1000 turns - 95.24 TPI
       1.3 mh - 196.34 ft lg - 3.28 pf Cself

Fres = 2434 Khz - no topload
        2.56 Pri turns - 0.71 uh

Fres = 1209 Khz - 10 pf topload
        5.15 Pri turns - 2.89 uh

Streamer Spark = 10" - 5.0 KV - 20 ma - 100 watts

The on-line JHCTES Ver 3.42 is limited to 0.5" sec rad because no one would
ever build a TC with  a smaller size secondary. Obviously I was wrong! The
original version does not have this limitation.

Note that the spark length for a Tesla coil is equal to

   Inches = A*(watts input - losses)

   A is a factor for each size of TC, and the method of measuring the spark.

   Losses depend on sec wire insulation, pri cap losses, pri wire size,
operating gap losses, etc.

   Note that this equation also limits the spark length when the watts input
is increased beyond a certain limit for a certain TC. This confuses many
coilers because they forget the losses will automatically increase when the
watts are increased increasing the voltages stresses on the sec wire
insulation, etc.

The 27 ohms sec resistance is a minor factor for this coil.
The sec self cap (Cself) only changes the Fres of the system.
Your spark length would be limited by the pri cap losses, sec wire
insulation, and the power supply. The power supply is probably producing
much less than 100 watts. It is possible for a coiler to measure these
variables individually but few coilers bother.

Your topload should be changed. Make a 10" * 3" toroid from a plastic toy or
use a metal dish (10pf). The topload capacitance and sec Cself are added
together for the total secondary system capacitance.

A recommended wire size for your primary is 10 AWG bare copper. A graph
showing primary wring sizes for classical TC's is shown in my Tesla Coil
Design Manual. There are many other graphs for Tesla coils also shown. These
graphs are based on data from real world coils and not available in any
other publications. Coilers have been using these graphs to design their
coils for over ten years.

John Couture

------------------------


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, September 18, 2003 5:39 AM
To: tesla-at-pupman-dot-com
Subject: Re: Primary construction


Original poster: The MCP <ejkeever-at-comcast-dot-net>

Thank you for the info. I've got a few quirks, however: When I use .75" dia
(2.35" circumfrence) times 1000 turns, I compute 196 feet of wire, not
394...
Something got doubled. But for some reason, we both got about 1.2 Mhz (The
simple calculator I used probably doesn't account for self-capacitance)...
???

At any rate, I'm currently using 2 turns, varying from 2.5 to 3.5 inches
high,
and it's working about as well as it was previously (2.5" streamers -- 3"
arcs). I'm beginning to wonder if something is wrong with the coil itself;
Is
the 27 Ohms (Measured DC) of resistance excessively high/low for a tesla
coil
like this? What about the large amount of self-capacitance caused by using
such fine wire?

Finally, how can I calculate the capacitance of the small coil of wire I
mentioned that I currently use as a topload? Plus, is there a difference
between the energy in the topload being stored as an electrostatic (toroid
topload) vs electromagnetic (I presume the little coil stores energy as EM)
field?

On Wednesday 17 September 2003 03:52 pm, Tesla list wrote:
  > Original poster: "John H. Couture" <couturejh-at-mgte-dot-com>
  >
  >
  > MCP -
  >
  > The JHCTES Ver 3.42 TC computer program.
  >
  > Pri - 2.5" rad -3.5" hg
  >
  > Pri Cap - .006 uf
  >
  > Sec - .75" rad - 10.5" hg - 1000 turns - 95.24 TPI
  >        5.03 mh - 392 ft lg - 3.69 uh Cself
  >
  > Fres = 1167 Khz - no topload
  >         5.34 Pri turns - 3.1 uh
  >
  > Fres = 606 Khz - 10 pf topload
  >         10.28 Pri turns - 11.49 uh
  >
  > Streamer Spark = 10"
  >
  > For other parameters go to
  >
  >      www.mgte-dot-com
  >
  > Click TESLA, JHCTES, Go to bottom of Book page.
  >
  > John Couture
  >
  > -------------------------------------
  >
  >
  > -----Original Message-----
  > From: Tesla list [mailto:tesla-at-pupman-dot-com]
  > Sent: Tuesday, September 16, 2003 10:04 AM
  > To: tesla-at-pupman-dot-com
  > Subject: Primary construction
  >
  >
  > Original poster: The MCP <ejkeever-at-comcast-dot-net>
  >
  > My two new TDK caps arrived today, meaning that I now have 6nF/40Kv of
tank
  > capacitor. However, this obviously throws the old setup completely out of
  > whack. I've been trying to get resonance again, but failed miserably.
  >
  > So, here are the specs:
  > Secondary: .75 inch dia, 10.5 inch wound, 1000 turns, 196 feet of 32
gauge
  > wire
  > Primary is helical, 5 inches in diameter, with 3.5 inches vertical to
work
  > with
  > Tank caps are 3 X 40Kv/2nF TDK caps, X-fmr is 5000/20 NST.
  >
  > I've tried using JavaTC at classictesla-dot-com, but it's not working. After
  > giving up in it, I tried using 2, 3, 4, 6, 8, and 13 turns, none of them
  > that
  > much better than the other. I've got more 22 gauge wire than you want to
  > know
  > about and about 10 feet of .375 inch copper pipe to work with. HELP ME,
  > PLEASE!
  >
  > PS, JavaTC says the coil resonates at 750 Khz. Is it on crack?