RE: Multiple Questions

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

Comments interspersed:

Original poster: "CJ Moore by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<wizard1234-at-home-dot-com>

Over the past two years I have had quite a few questions about tesla
coils but
was unable to confirm/deny any information 100%. While I do not think I
ever
will be able to, tapping the minds of everyone on this list will
certinally get
me somewhere. 
Questions
 
>1) Does the thickness of the wall in the secondary form affect
anything? if yes
>then what and how. (my secondary uses irrigation pipe - very thick
walled,
>about 1/2 inch pvc)
 
It shouldn't have any measurable effect on performance, though it sounds
like it would be very heavy!  What diameter is this?

>2) Is 85$ for a Maxwell Pulse Capacitor rated at 35kVDC, .030 uF +/-
10%, ~2uH
>E.S.L a good deal

There appear to be a large number of these on the surplus market
recently.  They are very compact for the amount of energy they can
store.  I know that Maxwell makes at least two grades of pulse caps,
differing by how many discharge cycles they are rated for.  I have a
.02uF/45kV Maxwell cap which amounts to 40.5 Joules.  It appears to be
many (4-8x?) times the physical volume of these .03uF/30kV caps, yet is
only 1.5X the 27Joule rating of them, so this leads me to speculate that
they may not be rated for the same number of discharge cycles.
 
>3) How do you find/become aware of/go to an auction for a power
company? (heard
>they did that)
 
>4) Where do you find the disc, electrodes, and shaft for a RSG

You can make electrodes from brass bolts or acorn nuts.  Just make sure
the acorn nuts are solid brass and not brass-plated.  Tungsten rods can
be bought from welding shops if you want to get more fancy or will be
using higher powered coils.  Several list members have advertised
tungsten rods for sale on this List recently.  Disks can be made of
Lexan (polycarbonate, not, Not, NOT Plexiglass or acrylic) if you don't
run at high power levels that would heat the electrodes, and Lexan can
be found at plastic dealers (see yellow pages under plastic
distributors).  G10 or phenolic is best as it won't melt, but is harder
to source.  The shaft is generally part of the motor.
 
>5) Is it acurate to say that you should have no more than 800 turns on
a
>secondary.

No.  Coils with twice that work just fine and may in fact be more
efficient by forcing you to have a comparably higher inductance primary,
which lowers spark gap losses.
 
>6) What are the advantages/disadvantages to each type of primary coil.
(this
>one will bring lots of discussion)
 
>7) What are good prices for NST

Free is best, though 15/60's are hard to come by.  I got 2 free 15/30's
for the asking, but had to pay $72 for my used 15/60.
 
>8) Is it worth it to use more than 2 NST's to try and acheive higher
current at
>a much lower voltage?

Higher voltage offer lower losses and lesser demands from the spark gap.
I would suggest paralleling 15kV NST's.
 
>9) I have run my previous coils for less than 30 seconds at a time,
many people
>have horror stories of things breaking, how long do you usually have to
run a
>coil to mess up a NST? (medium sized coil, average components)

It all depends upon how hard you push your components.  Like, how wide
is your spark gap?  This determines the peak voltage to your cap and
NST.  How high to you crank your NST input?  120V or 140V?  How
conservative is your cap voltage rating?  How old and frail is your NST?
For myself, I don't try to run it longer than 1-2 minutes at most, just
long enough to make a measurement or see if my latest "improvement" made
any difference.  I always set the volume to "11", but everyone "uses"
their coil differently.
 
>10) People have referecend neon sign shops many times on websites as
being good
>places to find NSTs cheap, however I have never seen or even heard of a
neon
>sign shop outside of tesla coil sites. I looked in the phone book and
found
>nothing? Do I live in some abnormal area or are they not so common?

Check the yellow pages under "signs".
 
>11) I had more...but I didn't write them down at the time, I will post
others
>later, this is all I can think of right now. 
 
Regards, Gary Lau
MA, USA