RE: larger than resonant (fwd)

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Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Fri, 1 Jun 2007 10:55:09 -0400
From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: larger than resonant (fwd)

There are actually two reasons to use an LTR cap over a mains-resonant
cap.

The most frequently cited reason is that should you open your static gap
too wide, a mains-resonant cap will resonate at 60 Hz with the NST
secondary and "ring_up", to whatever breakdown voltage your gap is set
to.  If your gap is set to break down at 50kV, it will get there, unless
your NST or your cap break down and smoke first :-(  

Using an LTR cap shifts the NST/cap resonant frequency away from the
mains-frequency, although it will still see some resonant-rise at 60 Hz.
If it did not, your gap would never fire if the variac was less than
100%.

A less often acknowledged reason to use LTR is that maximum streamer
length correlates to bang size - 1/2 * C * Vgap.  With the same gap
breakdown voltage (cap charging or bang voltage), a larger capacitance
will yield a larger bang and result in a longer streamer, even if the
BPS rate is less.  Of course the lower BPS rate will make for a less
white-hot and impressive streamer - it's your choice.

Regards, Gary Lau
MA, USA

> Date: Fri, 01 Jun 2007 05:54:39 -0400
> From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: larger than resonant
> 
> Hey everybody,
>      Can somebody explain to me the advantage to using a "resonant" or
> "larger than resonant" tank capacitance?  I seen coils get huge sparks
using
> LTR and also very small tank capacitors, so what is the point?
Thanks.
> Scott Bogard.