Re: Many questions

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

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

Hi,

At 01:06 AM 10/8/2002 -0400, you wrote: 

>
> I m a new coiler and have done a great deal of research to design the coil I
> m currently implementing.  I ll give all the specs and then ask the
> questions.  (please keep in mind the only part actually built is the primary,
> the rest can possibly be changed by recommendation) The coil transformer is a
> 15kV 450VA 30mA 60hz output neon light transformer. The capacitor is a 25kV
> .3uF box capacitor I bought off ebay.  


The cap size is too big.  For your static gap, you want 0.008uf.  See the chart
at:

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

I don't think your NST will even begin to charge such a large cap.  Sorry bout
that...

>
> The primary is 7 diameter 6 gauge copper wire wound in a helix with 4.17
> turns and approx 1.2 space between windings.  The secondary is 21AWG enameled
> magnet wire 1395ft wound on a 4.25 diameter pvc pipe 39 tall.  It is tuned to
> approximately 177kHz. The top load is a 30 x6.25 toroid.  The spark gap is a
> collection of 10-½ copper pipes (1.5 in length) screwed to a piece of
> plexiglass with around .025 gap between each and a fan blown over the top.  I
> got all these calculations by playing with the TC java tesla designer.
> However I m not sure if this is going to work correctly.  The low amount of
> turns on the primary seems odd to me (I know if I use the recommended .066uF
> capacitor (by another java designer) it says to wind 18 turns).


The Java designer works well.  Now you say 0.066uF for the cap so I am not sure
what cap you have there.  However, it sounds like you have done things pretty
well.



>
>  
>
> Questions:
>
>  
>
> Do you feel this should work?


Sounds good as long as the primary coil and cap size get figured out.


>
> What wire should I use to connect it all together and what type of
> connectors? I bought high voltage wire but it doesn t handle much current.


The wire from the NSTs can be thin high voltage wire.  The cap/gap/primary coil
circuit has hundreds of amps in it so try to use really "big" wire for those
connections.


>
> Is the spark gap appropriate?


Sounds fine.  I don't think you need all the gaps but you can easily select as
many as you need.


>
> What type of safety gap should I use?


Something like this:

http://hot-streamer-dot-com/TeslaCoils/MyCoils/BigCoil/protection.jpg


>
> How can I discharge the capacitor so I can work on the coil safely? I think
> shorting it would damage it. What can I use for a resistor to discharge it
> more slowly?



A bunch of like 1 or 10 Meg little resistors in a string hooked across it will
do the job.  You are right that directly shorting the cap is not good for it.


>
> How and where should I ground it?


To the nearest ground point.  Maybe drive a stake in the ground or something.


>
> Should I put a piece of Styrofoam in the inner part of the toroid and cover
> it with aluminum tape?


As long as the toroid has electrical contact to the top of the coil, the inside
of it does not matter much.


>
> How should I connect the toroid to the top of the coil and should I leave
> some blank pvc before the toroid?


Just any old piece of wire.  Best to space it up some.


>
> What do you recommend I use to coat the secondary?


polyurethane is very popular.  Shipping wrap is fast and easy.  Lots of options
there...


>
> If you could change something on this coil, what would you change?


Sounds fine right now.  You just need to work out some details and it should
work fine.

Cheers,

        Terry



>
>  
>
> Thanks for all your help,
>
>  
>
> Matthew Morrissette
>
> MIT frat boy Sophomore in Comp Sci and EE looking for fun with a tesla coil