Re: First run 6.5" coil- odd results? (fwd)
Subject: Re: First run 6.5" coil- odd results? (fwd)
From: Terry Fritz <twftesla-at-uswest-dot-net>
Date: Sun, 06 Jun 1999 11:49:21 -0600
At 10:33 AM 6/6/99 -0600, you wrote:
>Date: Sun, 6 Jun 1999 11:58:19 EDT
>Subject: First run 6.5" coil- odd results?
> Since I'm new to the list, let me introduce myself. My name is Scott,
>or "Lugnut" and I am very new to coiling. I wanted a good start, so I made
>and bought everything for my coil, except for Xformer...:_( Chances are I am
>doing something wrong but don't know it. I heard that my results were odd due
>to my Xformer, tell me what you think.
Welcome to the Tesla list!
> Well, here's my stuff: right now I'm getting 8" sparks maybe 9".
> secondary-6.5" OD PVC 1/4" thick wound to 26" 22 or 24 gauge...I
Assuming your wire is around .024 inches in diameter, your coil is around
44mH with a self capacitance of 12 pF. There are around 1100 turns on it.
> primary- flat pancake, 1/4" copper tubing spaced 1/4"
> 13 turns total.
Around 54 uH.
> capactitor- salt water type, 15 totally assorted bottles in a 10
> gallon fish tank-no oil and I'm not getting flashover. Probrobly due to
> my transformer's lack of power.
> Xformer- right now I have a horrble, beat up, but working 4000 volt
> Spark gap- 4 gaps at about 1 millimeter each.
> There are no bypass caps or safety gaps.
> Discharg terminal- Use everything from a nail to a 7" sphere. After
> tuning, I get the best results from the sphere, about 8" sparks. I have
> to use a nail to get sparks to the air, they get about 6" in the dark,
>(really dim, but I can feel, them <ouch!>.
Go with a sphere or any large smooth object. You need something with a
large surface area on the top of the coil for best sparks. You coil (the
secondary) is probably running around 160KHz
This system seems to need a primary capacitance of ~18nF. I don't think
your salt water cap can get this high. Your primary may be tuned to a
higher frequency harmonic like 320KHz. I think you may need around twice
the capacitance in the primary. Your system sounds like the primary and
secondary are not tuned to the same frequencies.
I would not try to touch the output arcs. In an untuned system, no telling
what is going on. In general, touching output arcs is avoided these days.
The voltage does not go along the outside of the body as thought for many
years. I goes right into you. The nerves don't react to the high
frequency but all the heating and cooking is the same as if it were DC. It
is not considered safe.
> Problem- I have no real idea if I am doing well or not because nobody
> that I've heard of uses the weak transformer that I have. If I buy two
> 12kv-at-30mA NST's, will I get 12x the sparks? That almost sounds
Well running systems with 12kV 60mA get about 36 inch arcs. It is
generally a square law thing. To get twice the distance you need four
times the power. But there are many variables...
> By the way, I'm 14 and showed my science teacher, she looked at it like
> I was doing something wrong...hmmmmm...maybe I am. Please help me out
> or even comment on my coil. I even need a name of sorts...you people
>are the best!
Science teachers always like to se "safe and sane" experiments. Like
growing beans or something. :-(' High voltage arcs tend to scare people.
She is probably worried that you will hurt yourself. She will get used to
I can't be completely sure of the numbers here, but it is my best guess...
Welcome and Cheers,
BTW - Write your posts to "tesla-at-pupman-dot-com" instead of "chip-at-pupman-dot-com".
Chip probably already said this...