Re: A newbie question

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

Original poster: Jim Lux <jimlux-at-earthlink-dot-net> 

At 07:48 AM 9/19/2003 -0600, you wrote:
>Original poster: "Gergely Nagy" <gergely.nagy-at-bluewin.ch>
>Hi All,
>
>Sorry for making you go all over this again, but I'd appreciate a bit of help.
>
>So, I've read the description and construction notes of George Trinkaus on 
>the TC and I would like to build one too. I went to hardware stores to 
>look for materials, but even to find pipes for the primary and secondary 
>would be a problem. George in his description goes with a 3.5" x 18" 
>secondary and a 7" x 5.75" primary. And this is what I can't find.
>So I thought I might reduce the sec. and the prim. to one half.

3.5x18 is fairly easy to come by... think cardboard mailing tube or 3" or 
4" PVC pipe.  Mailing tube may not be ideal, but will work just fine.. Make 
sure it's dry!, give it shot or two of some sort of paint (you'll get lots 
of suggestions...It probably doesn't matter much, as long as it's not a 
conductive paint (stay away from flat black!))

Make your form a bit longer than your secondary winding!.. you can always 
trim the form down if you need to but it's nice to have an area at the ends 
to stick tape onto, etc.


>1. In this case, would the #28 wire be adequat for the task or should I 
>look for a thinner? Same question  for the primary's #8 stranded wire.

Anything in the 20's will work... #24 is nice, #28 is getting mighty 
fine... whip out the old calculator and find a wire that will give you 
around 1000 or so turns on your secondary (the wire tables don't 
necessarily account for insulation thickness.. )  1000 turns in 18 inches 
is, uhhh... 0.018 inch diameter, which corresponds to AWG 25 (but that's 
with no insulation.. #26 or #28 would do... so would #24..(not like having 
900 turns instead of 1000 is going to make a huge difference)


>2. Transformer-wise, the booklet suggests something between 6000 and 15000 
>V and 30 to 60 mA. I guess the transformer at the lower end would be 
>sufficient.

Sufficient, but higher voltages are easier to make work... the spark gap is 
easier to adjust, and, here's the other thing.. MORE POWER... Neon 
transformers come in various standard currents (30 is common, 60 less so, 
120 really less so).. So, 12 kV at 30mA is twice the power of 6kV at 
30mA...  Scrounge for a 12kV or 15kV transformer...



>3. The other hardnut is the capacitor (as everywhere else). I found the 
>description of the beer-bottle capacitor in George's booklet and I think 
>it'd be OK to build it. There is just one thing which is not clear. So 
>when bottles are filled up and are in the "dishpan" and its filled up too 
>to within about 0.25" of the top, do you have to seal the "dishpan"? 
>Otherwise if I got it right, the interconnected bottle terminals is one 
>pole and the metal inside of the "dishpan" is the other.   OR  Would you 
>rather suggest to buy the capacitor? Since it wouldn't be a big TC I am 
>sure that I won't need a 0.3uF 35Kv capacitor. How can I figure out what I 
>need?

Build a geek group beer bottle cap.. Plastic 5 gallon buckets.. their 
website has instructions

Save those pennies for a MMC


>4. Since I could get hold of as many plexiglas as I can, I tought I would 
>build a cage around the primary circuit for the sake of security. BUT 
>would plexiglas securize anything at all at these high voltages? Is wood 
>any better? And wouldn't heat evacuation be a problem? First I thought to 
>put everything but the coils under the cage but maybe spark gap should be 
>left in the open air so it can be cooled easily.


Acrylic (Plexiglas) is fine as a substrate and building material.. 
Polycarbonate is even better (doesn't shatter as easily when 
sawing/drilling)... Don't seal the spark gap... it dissipates a fair amount 
of power.  You should consider getting a small fan (i.e. a muffin fan or 
bathroom fan, etc.) to blow on the gap. Even a slow movement of air greatly 
improves performance.

My preferred "easy spark gap" is a pair or three sections of copper pipe 
arranged with axes parallel. (if you use three, you only need to move the 
middle section to adjust all the gaps... arrange them in a triangle, not a 
straight line)

  O
O O

not

O O O

HV goes to the bottom two pipes, top pipe gets moved to adjust gaps. fan 
blows along the axis of the pipes.

sweat couplings are cheap and readily available
Or, get a tubing cutter and cut some 1-2" chunks off a piece of pipe.  3/4" 
or 1" is probably about the right diameter.. 1/2" is kind of small for this 
application.



>I know I got many things to learn but I am 100% motivated and I know I can 
>do it. Of course security is very important, so if there are some other 
>things I should know about (and what is not at pupman-dot-com on the safety 
>sheet) please tell me.
>
>If you didn't get tired of my questions and could read it until here, I'd 
>be really happy to read your answers.
>Thanks you very much.
>
>Greg
>a humble newbie