Wire Length
Date: Sun, 11 Jun 2006 11:47:10 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: wire length
Original poster: "Gates" <ryker@isys.ca>
How do you calculate the length of wire I use to make my secondary coil? What's
the formula?
Thanks gang
Date: Sun, 11 Jun 2006 11:55:44 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: wire length
Original poster: Vardan
<vardan01@twfpowerelectronics.com>
Hi,
Today, the "length of the wire" has been found not to matter as far as streamer
length or anything. There are a few who still think it is based on 1/4
wavelength or something, but I totally disagree with them as do most.
You want a coil say 4 inches in diameter and maybe two plus feet long. About
900-1200 turns works fine.
The length of the wire is:
3.14159 x secondary diameter x number of turns
So a 4 inch secondary with 1000 turns uses 1050 feet of wire. Much wire data is
here in the back:
http://hot-streamer.com/temp/FormulasForTeslaCoils.pdf
Also see John's notes here:
http://hometown.aol.com/futuret/page5.html
Cheers, Terry
Date: Mon, 12 Jun 2006 00:17:28 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: wire length
Original poster: "Dr. Resonance"
<resonance@jvlnet.com>
The wire length is not that critical as long as it falls within a certain range
for the number of turns. The larger the dia. of the secondary coil the more
potential (voltage) your coil will achieve although plasma based on input power
is really a better indicator of spark length (Freau equation). Most
experimenters plan on using 1000 to 1400 turns on either a 4 inch or 6 inch dia.
(ID) white PVC tube for excellent performance with a copper tubing subdivided
sparkgap.
Contact me off list and I can email you the plans for a nice performing coil
using a 4 inch ID PVC tube. It runs on a 12 kV 60 mA neon sign transformer and
produces sparks over 4 feet long. A nice lightweight portable coil for home or
school use.
Dr. Resonance
Date: Mon, 12 Jun 2006 00:17:50 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: wire length
Original
poster: "Dr. Resonance" <resonance@jvlnet.com>
It should be noted that Terry's sample calculation is for a 4 inch OD (outside
dia.) tube. If you are using standard PVC schedule 40 water pipe (like Home
Depot stuff) then the calculation would be for 4.5 inch OD tubing with 1,000
turns and becomes:
sec wire length = (3.14159 x 4.5 x 1000 turns)/12 in/ft. = 1,178 feet of
wire.
If you are using 24 AWG double-build 200 degree C. magnet wire then the 1,000
turns would work out to a lineal winding length of 22.5 inches. Allow 3/4 inch
on top and 3/4 inch on bottom of your tube so tube length (total) before winding
is 24 inches.
A .0188 uF 32 kV MMC cap design (16 pcs of 0.15 uF 2 kV MMC caps in series)
with a copper tube spark gap (200 CFM fan on each end --- one pushing and one
pulling air through a 6 inch dia. pvc tube) will produce 58 inch long sparks
with a 12/60 NST. Very compact and good performance for a small portable coil.
Be sure to use a strike rail around the primary coil.
Dr. Resonance
Date: Mon, 12 Jun 2006 09:02:17 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: wire length
Original
poster: "Scott Hanson" <huil888@surfside.net>
DC -
Is something wrong with your cap calcs here?
Eight of the C-D 15uF 2KV caps in series will provide the specified .0188uF
value, but at a voltage rating of only 16KV.
Sixteen of the same caps in series will provide only .0094uF at a more
conservative 32KV.
What is your recommended value: .018uF, or .009uF?
Did you mean TWO parallel strings of 16 caps each?
Regards, Scott Hanson
Date: Mon, 12 Jun 2006 11:19:11 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: wire length
Original
poster: "Barton B. Anderson" <bartb@classictesla.com>
Hi Scott,
I use 2 parallel strings in my .0188 uF MMC. It's only 32 caps, so it's low cost
and still robust. I think D.C. meant to call out 2 strings.
Take care, Bart
Date: Mon, 12 Jun 2006 14:14:41 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: wire length
Original
poster: "Dr. Resonance" <resonance@jvlnet.com>
Thanks for bringing this matter to my attention. Working too late at night
again!
It is 16 in series for .0094 uF 32 kV total capacitance per string --- then, two
strings connected in parallel for the .0188 uF value total.
Dr. Resonance
----- Original Message ----- From: "Tesla list" <tesla@pupman.com>
To: <tesla@pupman.com>
Sent: Monday, June 12, 2006 10:02 AM
Subject: Re: wire lengnth
>Original poster: "Scott Hanson" <huil888@surfside.net>
>
>DC -
>
>Is something wrong with your cap calcs here?
>
>Eight of the C-D 15uF 2KV caps in series will
provide the specified
>.0188uF value, but at a voltage rating of only
16KV.
>
>Sixteen of the same caps in series will provide
only .0094uF at a
>more conservative 32KV.
>
>What is your recommended value: .018uF, or
.009uF?
>
>Did you mean TWO parallel strings of 16 caps
each?
>
>Regards,
>Scott Hanson
>----- Original Message ----- From: "Tesla list"
<tesla@pupman.com>
>To: <tesla@pupman.com>
>Sent: Sunday, June 11, 2006 11:17 PM
>Subject: Re: wire lengnth
>
>
>>Original poster: "Dr. Resonance" <resonance@jvlnet.com>
>>
>>
>>
>>It should be noted that Terry's sample
calculation is for a 4 inch
>>OD (outside dia.) tube. If you are using
standard PVC schedule 40
>>water pipe (like Home Depot stuff) then the
calculation would be
>>for 4.5 inch OD tubing with 1,000 turns and
becomes:
>>
>>sec wire length = (3.14159 x 4.5 x 1000
turns)/12
>>in/ft. = 1,178 feet of wire.
>>
>>If you are using 24 AWG double-build 200 degree
C. magnet wire then
>>the 1,000 turns would work out to a lineal
winding length of 22.5
>>inches. Allow 3/4 inch on top and 3/4 inch on
bottom of your tube
>>so tube length (total) before winding is 24
inches.
>>
>>A .0188 uF 32 kV MMC cap design (16 pcs of 0.15
uF 2 kV MMC caps
>>in series for .009 uF -- two series circuits in
parallel) with a
>>copper tube spark gap (200 CFM fan on each end
--- >>one pushing
>>and one pulling air through a 6 inch dia. pvc
tube) will produce 58
>>inch long sparks with a 12/60 NST. Very compact
and good
>>performance for a small portable coil. Be sure
to use a strike rail
around the primary coil.
Date: Mon, 12 Jun 2006 14:14:50 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: wire length
Original
poster: "Dr. Resonance" <resonance@jvlnet.com>
Two strings in parallel is correct. Working too late at night again!
Dr. Resonance
>Original poster: "Barton B. Anderson" <bartb@classictesla.com>
>Hi Scott,
>I use 2 parallel strings in my .0188 uF MMC. It's
only 32 caps, so
>it's low cost and still robust. I think D.C.
meant to call out 2 strings.
>Take care,
>Bart
>Tesla list wrote:
>
>>----- Original Message ----- From: "Tesla list"
<tesla@pupman.com>
>>To: <tesla@pupman.com>
>>Sent: Sunday, June 11, 2006 11:17 PM
>>Subject: Re: wire lengnth
>>
>>
>>>Original poster: "Dr. Resonance" <resonance@jvlnet.com>
>>>
>>>
>>>
>>>It should be noted that Terry's sample
calculation is for a 4 inch
>>>OD (outside dia.) tube. If you are using
standard PVC schedule 40
>>>water pipe (like Home Depot stuff) then the
calculation would be
>>>for 4.5 inch OD tubing with 1,000 turns and
becomes:
>>>
>>>sec wire length = (3.14159 x 4.5 x 1000
turns)/12
>>>in/ft. = 1,178 feet of wire.
>>>
>>>If you are using 24 AWG double-build 200 degree
C. magnet wire
>>>then the 1,000 turns would work out to a lineal
winding length of
>>>22.5 inches. Allow 3/4 inch on top and 3/4 inch
on bottom of your
>>>tube so tube length (total) before winding is
24 inches.
>>>
>>>A .0188 uF 32 kV MMC cap design (16 pcs of
0.15 uF 2 kV MMC caps
>>>in series) with a copper tube spark gap (200
CFM fan on each end
>>>--- one pushing and one pulling air through a 6
inch dia. pvc
>>>tube) will produce 58 inch long sparks with a
12/60 NST. Very
>>>compact and good performance for a small
portable coil. Be sure
>>>to use a strike rail around the primary coil.
>>>
>>>Dr. Resonance
>>>----- Original Message ----- From: "Tesla list"
<tesla@pupman.com>
>>>To: <tesla@pupman.com>
>>>Sent: Sunday, June 11, 2006 12:55 PM
>>>Subject: Re: wire lengnth
>>>
>>>
>>>>Original poster: Vardan <vardan01@twfpowerelectronics.com>
>>>>
>>>>Hi,
>>>>
>>>>Today, the "length of the wire" has been found
not to matter as
>>>>far as st....
>
Date: Mon, 12 Jun 2006 14:15:04 -0600
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: Wire Length
Original poster: Jared E
Dwarshuis <jdwarshui@emich.edu>
The classic equation for an air cored inductor, derived with Maxwell's equations
is:
L = u Nsqrd Area / length
However the numerator and denominator can be multiplied by 4pi, yielding:
L = u (2pi R N) sqrd / 4pi l
Since: 2pi R N is wire length , we can write:
L = u (wire length)sqrd / 4pi l*
I put a star next to the length because solenoids in the real world do not have
a perfectly uniform magnetic field. We then need to make our solenoid length
just a little bit longer to get the correct inductance.
Now we can talk about standing wave resonance in a Tesla coil. We will use a
simple version of capacitance in the lc equation.
We can use a sphere for our top end capacitor. The capacitance of a sphere is:
c = 4pi e R*
I put a star next to the radius because a Tesla coil inductor has self
capacitance that must be accounted for. We find that R, in real life is going
to be a bit smaller due to the self capacitance of the inductor.
Now we examine Tesla's equation:
C/4 Wire length = 1/ 2pi sqrt (lc)
Substituting from above for L and c, we get:
C/4 Wire = C/ Wire' x 1/2pi sqrt (l*/R*)
Set: 2pi = sqrt (l*/R*)
Then:
C/ 4 Wire = C/Wire'
Inverting frequency gives us the period:
4 Wire /C = Wire'/C
A casual inspection shows that this equation can only be satisfied if Wire' = 4
Wire
Now we apply the Lorentz equation, as we are observing time dilation and
distance contraction.
With a Gamma of 4, we predict that the velocity of waves down the length of wire
in our inductor will measure the sqrt(15/16)C
Thus, the actual wave velocity is reference frame dependant.
Tesla must not have understood all of this (in the late 1880's) or he would have
found the general form of the equation which describes node formation.
n/2 C/w = 1/2pi sqrt ( u x (w/2n)sqrd x 2n/ 4pi l* x 4pi e R*)
Where n = 1/2, 2/2, 3/3...........
The nodality equation also yields a gamma of 4
Sincerely: Jared Dwarshuis (and by proxy), Lawrence Morris