Re: tesla coil

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Mike,

At 10:36 PM 11/6/2002 -0500, you wrote:
>I am building my first tesla coil and am pretty limited in my 
>understanding of electronics. I bought plans off the web that were posted 
>on e-bay and have some questions I think you can answer.
>Between the transformer and the spark gap is a component called a choke 
>constructed of a ferrite torid core -what does it do ?

They used to use a coil of wire to stop bad signals from hurting the NST 
(neon sign transformer).  It really does not work at all...  But more 
modern things will make it easy.  You could almost get away without 
anything in the place of the choke for a first coil.  What you need is an 
LTR sized capacitor matched to your NST and spark gap.  I will guess you 
have a simple static gap for a first coil.  Here is the magic chart:

http://hot-streamer-dot-com/temp/MMCcapSales.gif

Pick a cap size for static gap LTR at 60Hz to match your NST.  A fellow 
named Chris Boden can then get you the caps you need.  I don't have Chris's 
E-mail address here but we can find him pretty easy for you :-)  I would 
like to know what kind of transformer you have to help out with further advice?

>
>The plans call for a pvc pipe with aluminum sheets rolled between plactic 
>sheets with a value of .005 uF  40,000 volts pr cap. Is there any other 
>caps  I can substitute for this labor intensive project ?  If so are they 
>durable ? I would need a good description to purchase them.

Don't mess with that.  Just get nice caps from Chris.  Simple and easy.  We 
string commercial caps together to get the caps we need:

http://hot-streamer-dot-com/TeslaCoils/MMCInfo/mmcinfo.htm

>I heard that ac caps do not hold a charge once the electricity is turned 
>off. Any comments ?.
>I have to make two. Are they wired in series or parallel.?

I don't think you need two caps.  We put a bunch of little resistors across 
the caps to drain the charge safely.  All caps can hold a charge after the 
power is turned off, but adding resistors takes the charge safely away.  AC 
caps "can" hold a charge so the plans are wrong there.


>
>What relevant information do you need from my tesla coil blueprints so I 
>can construct a  torid ?

A toroid is just a big metal blob at the top of the coil.  Most people make 
them from aluminum coragated heating duct from the hardware store.  Check 
out some of the sites at:

http://j.webring-dot-com/hub?ring=teslaring&id=265&hub

The toroid is not super critical so just something that looks close for a 
first coil will do fine.

Hope this gets you on the right track for what you need.  It is sort of 
complex, but you will catch on fast :-)  Study other people's coils and 
build yours like theirs and it will work fine.  The "first" coil is always 
hard, but once you do it, everything will make sense.

Cheers,

         Terry


>Thanks  Mike Biggs