RE: Just about

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

Original poster: "Lau, Gary" <gary.lau-at-hp-dot-com> 

Hi Nir:

Extracted from your web site, with my comments interspersed:

 >Plate: A simple plywood rectangle with holes for the holding poles

 >NST: 220 V~ 50 Hz to 12 KV~ 0.03 amper.

 >Spark gap(not yet built): Two simple exposed wires in a glass gar.

Bad idea.  The electrodes should be thermally large to dissipate the
heat, and have air forcefully blown through the arc.  Your wires would
quickly get red hot.  Use two or more parallel copper pipes for a
cylinder gap.  Ask about the required spacing and how to set it before
using it, or you will blow your NST.

 >Capacitor(not yet acquired): Data required. (This is where you come!)

Using a static gap, I would recommend a .016uF cap.  If you have a
12kV-rated NST, your cap should have a voltage rating of at least 1.414
x 12kV, or 17kV.  Ten 0.15uF/2kV polypropylene film caps in series will
give you a .015uF/20kV MMC cap.  See www.thegeekgroup-dot-org/mmc.  I don't
know if they ship internationally, but this is the kind of cap you need.

 >Primary coil: 5.5 turns of copper refrigeration pipe held by barb wire
on polished
 >wooden poles that are based in holes in the wooden base (Poles have
several >proximity levels that can be switched).

I have to be blunt here - scrap what you have and start over.  The
primary needs to be as distant from the top of the secondary as
possible, or else the top load will arc directly to it.  Also, while
intuition suggests that the pri to sec power transfer will be better as
the two are brought closer, other problems occur.  Instead, the primary
should be a flat spiral at the base of the secondary.  The inside
diameter should be about 2 inches larger than your secondary diameter,
the turn-to-turn spacing should be as close as possible without touching
(typically about 1/4 inch space between turns).  The number of turns
will depend on your secondary and top load sizes, but is typically 8-12
turns.

 >Secondary coil: 0.41 wire coiled around 93 cn (More then a meter in
total) of PVC >pipe witch is sealed with ducktape coverd (bought)
plastic cups. The PVC pipe is >hollow and has small holes in several
locations (for wires, etc). The PVC pipe is >screwed to the plate.

Not sure, you may want to start over here too.  The aspect ratio, the
secondary winding length divided by the PVC diameter, generally doesn't
exceed about 5.  I didn't see what your PCV diameter was, but it looks
too long/too thin.  Also, if you have holes in your PVC, this is bad,
especially if wire goes through it.  The wire must be kept on the
outside of the pipe.  I'm not familiar with the HV electrical
characteristics of duct tape.  The silver makes me think of conductive
aluminum - bad.  The number of secondary wire turns is typically
1000-1600 turns.  I think if you used the same wire and PVC pipe but
wound only half of the present length, you would have 1100 turns and
probably a more acceptable aspect ratio.  Just make sure there are no
holes!

 >Discharge terminal: A simple 5 cn in radius casted iron ball that has a
bolt screwed >to its bottom and a wire from the secondary is soldered to
the bolt therefor conection >the two together. The iron ball sits on a
small hole in the PVC's plastic cup and is >crazy-glued to it.

No, the discharge terminal (or top load) must be much larger.
Performance has been found to improve as the top load size increases.
There is no formula for calculating the optimal size, but it's often as
large as the secondary is long.  A toroid (donut) shape is generally
preferred.  And the topload surface should be as smooth and free of
bumps as possible.

Sorry for all the bad news.  You should spend some time reviewing the
countless Tesla coil web sites and see how folks typically build their
coils.  My site is at www.laushaus-dot-com/tesla.htm.  It not that we're
blindly conforming to age-old practices, in fact coils today look very
different than coils popularized just 30-40 years ago.  We build them
this way today because (recent) experience and peer review has shown
that this gives the best results.

Regards, Gary Lau
MA, USA

 >Original poster: Nir Weingarten <nirzvi-at-yahoo-dot-com>
 >
 >Cheers to all.
 >
 >It is me once more yet this time I have a web page
 >that could help you help me so please visit:
 >http://planet.nana.co.il/Jufid/nir/nir.htm
 >
 >The page contains probably all of the information
 >about my very first nearly completed TC (with
 >pictures, plans etc...), and at its end is a small
 >list of the issues I need to deal with.
 >I assure you that your help will not be in vain!
 >
 >Thank you all
 >Nir (NOT NEAR) Weingarten, Israel


=====

Best wishes

                                                Nir(NOT NEAR) Weingarten

Israel