Re: newbie question - spark gap and toroid

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

Original poster: "michael curtiss" <lucknau-at-yahoo-dot-com> 


Hi there,

I guess I'd be worried about heat affecting your SG.
The spark gap gets extremely hot, and aluminum melts
at around 1220 degrees Farenheit (660 deg C), while
copper melts at about 1981 degrees F (1083 deg C).  My
experience with metal melting is from bronze and
aluminum casting, so the previous post sounds about
like what I'd expect to see when I've casted aluminum
in the past but melted it at too high a temperature:
pits and holes till it looks like a sponge.

But you do have the thing made already, right?  It
might be fun to see how it holds up, at least.


--- Tesla list <tesla-at-pupman-dot-com> wrote:

 > Original poster: "Gregory Hunter"
 > <tesla_39560-at-yahoo-dot-com>
 >
 >  > Original poster: "ho \[shu\] huang"
 >  > <shuhuang-at-singnet-dot-com.sg>
 >  >
 >  > Hey!
 >  >
 >  > I've got my tesla coil to work but I've got a
 > couple
 >  > of quick questions for
 >  > you pros out there: -
 >  >
 >  > 1. My SG spark gap's made from aluminium curtain
 >  > rail, not copper pipe. The
 >  > rail is flat, so it's easier to mount. Does it
 >  > matter? My coil works, but
 >  > I'm not sure if aluminium hinders performance in
 > any
 >  > way.
 >  >
 >  > 2. Does it matter that air isn't blown directly
 > at
 >  > the sparks? Do the
 >  > sparks require a lot of air to be "quenched", or
 >  > will a bit of moving air
 >  > be enough? In other words, is more wind better?
 >  >
 >  > My spark gap (pic here:
 >  >
 > http://web.singnet-dot-com.sg/~shuhuang/spark_gap3.jpg
 >  > ) sparks at the ends of the rails, which is sort
 > of
 >  > shielded by the 10mm
 >  > thick plastic support. I can easily reconfigure
 > it
 >  > so that the sparks get
 >  > most of the breeze from the fan, but I'm
 > wondering
 >  > if it's worth the
 >  > effort. The fans blow, rather than suck, BTW.
 >  >
 >  > 3. I used 2 aluminium wok covers joined together
 >  >
 >
(http://web.singnet-dot-com.sg/~shuhuang/tesla_coil_lab.jpg
 >  > ), ~210mm wide and
 >  > 320mm in diameter, as a toroid but I suspect a
 >  > traditioanl toroid might
 >  > work better. Believe it or not, I'm actually
 > having
 >  > a hard time flexible
 >  > drainage pipe. It's apparently not used very
 > often
 >  > any more...where I live
 >  > (SIngapore) anyway. I came across the pool float
 >  > toroid design on a
 >  > webpage, and I've found one on sale cheap. It's
 > 23"
 >  > in diameter and 8"
 >  > thick. Is that too big a toroid for my 15kV 30mA,
 >  > 90mm 900 turns AWG 24
 >  > wire secondary coil, set up?
 >  >
 >  > thanks!
 >  >
 >  > Shu
 >
 >
 > Shu,
 >
 > Nice photos. Thanks for sharing.
 >
 > I don't know about aluminum for spark gap
 > electrodes.
 > I've heard aluminum soon gets full of pits and holes
 > until it looks like a sponge. I have no first-hand
 > experience with it however. I've always used copper
 > or
 > brass electrodes. On the other hand, it sure is a
 > nice-looking spark gap you built there--very neat
 > and
 > professional. I think I'd go with the reality
 > test--if
 > the spark gap works well, don't worry about the
 > aluminum.
 >
 > Moving air can have a profound effect on spark gap
 > performance. Try blowing a jet of compressed air
 > through the thing and see see what happens. If
 > forced
 > air gives noticeable improvement, then you'll have
 > to
 > do something about your air flow.
 >
 > I think a 23" X 8" toroid is too big for a 15kv/30ma
 > NST system. Child-size 20" x 5" vinyl pool toys are
 > common in the US. See if you can find one of those.
 >
 > Actually, the Wok covers make a pretty neat-looking
 > terminal. People use all kinds of crazy stuff for
 > top
 > loads. Why not Wok covers? The important thing is
 > that
 > it woks well, um, I mean works well.
 >
 >
 >
 >
 > =====
 > Gregory R. Hunter
 >
 > http:\\hot-streamer-dot-com/greg
 >
 >
 >
 >