Re: Multiple Questions

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

Original poster: "Jason Petrou by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jasonp-at-btinternet-dot-com>

Hi there

> 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)

Theoretically yes... most materials are not completely RF invisible so
thickness does matter. I would aim for a thin walled pipe, perhaps 1/8 or
even 1/16 of an inch... makes for better coupling. PP (polypropylee) is
almost invisible to RF and is usually considered as the best to use.

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

Yes, pretty. You can get them for lower but new they are in the triple
figures. If you can get more I'd buy half a dozen and put them up for sale!!
Bear in mind you will have to have quite a large power supply (MOT type
possibly or Pig) to charge 0.03uF or a very low break rate.

> 3) How do you find/become aware of/go to an auction for a power company?
(heard
> they did that)

Not entirely sure what you mean.. if you mean HV parts auction i cant help
there

> 4) Where do you find the disc, electrodes, and shaft for a RSG

Right, this is more like it. The Disc for an RSG is usually either made from
tufnol (resin impregnated fabric) which has been *PERFECTLY* machined on a
milling machine to make a perfect disc. For a motor, a bench grinder would
probably do the job very nicely. Electrodes can be brass acorn nuts,
tungsten rod, whatever. (NOT aluminium - I tried it)

> 5) Is it acurate to say that you should have no more than 800 turns on a
> secondary.

Nope - many people use between 1000 and 2000 turns on their coils,
especially on the big ones. Remeber though, long thin secondaries have a low
inductance and have worse coupling than fatter ones.

> 6) What are the advantages/disadvantages to each type of primary coil.
(this
> one will bring lots of discussion)

Unfounded. Helical coils give the best coupling while they are more prone to
strikes from the coil itself. Archemidies spirals are the least likely to
get hit, but have to be moved to give the best coupling. A good choice is
the inverse cone, which is essentially a spiral bent upwards at maybee 10-15
degrees. Lots of discussion here - personally I would go for the flat
spiral, but there you go...

> 7) What are good prices for NST

Depends entirely on the age/supplier/manufacturer. Some people throw away
signs when they are broke with perfectly good NSTs on them. Some good makes
to look out for are Jefferson, Transco, Franceformer and Allason (?).
Jeffersons are usually the best for TC work - they seem to be very robust. I
reckon if youre charged under about $50 for a working 12/60 youre on the
right track

> 8) Is it worth it to use more than 2 NST's to try and acheive higher
current at
> a much lower voltage?

Well usually yes. If you paralell up say 3 NSTs to get 3x30 (i.e. a 12/90
NST) you have a more powerful xfmr, and more power = bigger sparks :) The
voltage is not affected here - it is the current that goes up, voltage stays
the same. Remember if youre going to try this, get 3 identical NSTs, or bad
things happen, like burnt out secondaries, carbon tracking, etc.

> 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)

If it it is properly protected with a filter (see www.hot-streamer-dot-com for
terry's filter - best around) your NST will essentially last for ever. If
you really abuse it, then maybee weeks, months, it really depends on the
transformer. Some are lucky, and get yoears of service out of an NST with no
filter at all... but I would use a filter :)

> 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?

If you cant find NSTs in your local area look on eBay - there are dozens of
NSTs, MOTs, Obits and pigs for sale

> 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.
>
> I do realize that some of these questions are not very scientific, but
they are
> related to Tesla Coils. I apprcieate any answers you have, regardless of
your
> experience.

No problem - good luck (& have fun :)

Jason