Re: Got my 6-incher going!

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "H.S. J." <hsheltonj@xxxxxxxxx>

The tank caps prolly get warm because of voltage spikes.

Voltage spike for 15kV NST Is 21210...exactly 1210v over the rating 
of your doorknob caps.  If they get HOT...like you cant touch them 
after discharge because they are so hot...thats like very bad...If 
its just barely above ambient temp..you will prolly be fine.  Like 
said before, try seeing if the capacitance goes down darastically 
after they get warm.


Thank You,

H.S.J.



You may reply back at: <mailto:hsheltonj@xxxxxxxxx>hsheltonj@xxxxxxxxx


----- Original Message ----
From: Tesla list <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Sent: Friday, April 20, 2007 8:54:51 PM
Subject: RE: Got my 6-incher going!

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Hi Ben:

That's a nice, neat coil layout your have - I tip my top-load to you ;-)

My comments and suggestions are:

1) On the NST protection circuit, replace the RF chokes with large,
ceramic-cased wire-wound resistors, 500-2000 Ohms, 50+ Watts.  It has
been shown that L-C filters as you have actually make matters worse,
creating their own resonances.  I suspect that's why you saw the
flashovers on the caps.  I know - they won't fit into the footprint of
your chokes :-(

2) Your doorknob tank capacitor uF value sounds good, but as you said,
their 20kV rating sounds too low to be safely used with a 15kV NST.  I
see that you found them to get warm after use.  Do you have a
capacitance meter to see if their value drifts when warm?

3) If you're using a 15/60 or 15/90 NST, you should be able to use a
much larger top load than a mixing bowl.  Could it be that you just
didn't have enough primary turns to tune a larger top load?

Regards, Gary Lau
MA, USA

> Original poster: Ben Buxton <bb@xxxxxxxxxx>
>
>
> After much research, list archive browsing and many many weeks of hard
> work, my first coil is up and running! So far I've only managed 80cm
> (~31 inch) arcs from the 15kv/90mA supply, but I would guess that it
can
> be improved either with a sucker gap or closer pri-sec coupling (now
> 4cm)...? Otherwise my TCT shows good resonance at 180KHz.
>
> Details, photos and vids at 
<http://bb.cactii.net/archives/000176.php>http://bb.cactii.net/archives/000176.php
>
> Ben
>



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