Re: BEGINNER PLANS FOR SCIENCE PROJECT PLEASE HELP

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

Original poster: "Philip Brinkman" <peeceebee-at-mindspring-dot-com> 

For my spark gap (the Richad Quick type) I just glued the copper pipes in
place (I used 7 pipes) spaced them with a penny ( 1 mm) dont mess with all
the hole drilling and bolting the pipes in place...just some 2 part epoxy
works great..fast and strong. I use my wife's hair dryer to quench the
spark and cool it off.


 > [Original Message]
 > From: Tesla list <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Date: 11/20/2003 9:55:13 AM
 > Subject: Re: BEGINNER PLANS FOR SCIENCE PROJECT PLEASE HELP
 >
 > Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net>
 >
 > Here we go with all the opinion stuff... I'd really, really recommend
 > against the carriage bolt needle gap (ends of the bolts are the gap) or
 > hemisphere gap (heads of the bolt) approach, and advocate the "3 copper
 > tube" gap.  The cost is about the same.
 >
 > a) The point on the needle gap gets very hot very quickly, radically
 > changing the spark gap characteristics.  This makes tuning a problem,
 > because as the coil goes into and out of tune, the current through the gap
 > changes, changing the heating, changing the timing relative to the AC
 > charging cycle, etc.
 >
 > b) Thermally, it's hard to cool the needle gap, because the entire heat
flow
 > path is through the bolt, and steel just isn't all that wonderful a
 > conductor, either electrical or thermal. It also doesn't have much surface
 > area.
 >
 > c) You've got to figure out some sort of wire lugs to attach the wires to
 > the gap terminals either way.
 >
 > d) Adjusting the needle gap is a pain.  You have to have two nuts on each
 > bolt, some sort of thing to stick the bolt through (usually an angle
bracket
 > or a piece of plastic. If you use plastic, there's the "melting support"
 > problem.
 >
 > e) Most hardware store bolts (unless you use brass carriage bolts, which
are
 > hard to find in bigger (1/4" and up) sizes) are plated with either Cadmium
 > or Zinc, both of which are toxic and will be vaporized by the spark.  To
get
 > a reasonable gap size with this approach, you're looking at 1/4" carriage
 > bolts minimum, and probably something like 3/8".
 >
 > ---
 > with a 3 copper tube gap, the spark area is spread over the entire length
of
 > the tube, so you're less likely to get little redhot spots
 > with a 3 copper tube gap, two of the tubes (which the wires are connected
 > to) can be permanently attached and don't ever need to move. All the
 > adjustment is done with the third tube
 > It's very easy to make a cooled/blown 3 tube gap, which greatly improves
 > performance, even on a small NST powered coil
 >
 > On my 15/30 powered coil, changing from a bolt head gap to copper pipe
 > dramatically improved performance, and adding a small muffin fan to blow
 > over the pipes also greatly improved performance.
 >
 > Arrange the tubes in a triangle (axes of tube parallel)
 > A      B
 > O      O
 >       O
 >       C
 >
 > A and B are bolted down, and have the two HV wires attached.  C is the
 > adjustable one.  There are lots of ways to attach them, but a bolt through
 > the length, with a suitable washer over the end, works very nicely.
 >
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Wednesday, November 19, 2003 7:36 PM
 > Subject: Re: BEGINNER PLANS FOR SCIENCE PROJECT PLEASE HELP
 >
 >
 >  > Original poster: "Laurence Davis" <meknar-at-hotmail-dot-com>
 >  >
 >  > Ravi,
 >  >    the multi-gap spark gap designs are helpful for performance for
medium
 >  > to larger coils,
 >  > but you can also build a simple single point gap.  It won't perform as
 >  > well, but still provides the
 >  > function of a spark gap.  A single point gap can be as simple as two
 >  > carriage bolts mounted on L brackets.
 >  >
 >  > I'm sure you've read the tesla safety faq's, but do so if you haven't.
It
 >  > hasn't been mentioned,
 >  > but remember the spark gap is comparable to a welders spark, which
means
 >  > DON'T look directly
 >  > at it.  Use a welding shield from a mask and you can get these
separately.
 >  > Even if you know
 >  > the safety issue here, kids and teachers in your class may
 >  > not.  Electricity can be fun, but blindness
 >  > is not.
 >  >
 >  > be safe.
 >  >
 >  > just my 2 cents.
 >  > larry.
 >  >
 >  > _
 >  >
 >  >
 >