Re: [TCML] upgraded NPT to 15/60

[Gary Lau <glau1024@xxxxxxxxx>]

Hi Joe,

Using .04uF with a 15/60 and SRSG is probably unusual.  My particular
(Jefferson) NST seems to become uniquely supercharged when operated at a
Variac'ed up 140VAC, and it would be irresponsible of me to suggest that
yours will behave similarly, but who knows!

Finding large toroids is difficult, and finding ready-made, economical ones
is next to impossible.  I paid to have a custom-made 7x30 foam core machined
for me, and I covered it with epoxy and AL tape, detailed at
http://www.laushaus.com/tesla/foamtoroid.htm.  I purchased that toroid and
created that web page at least 8 years ago so I can't suggest how prices may
have changed.

Regards, Gary Lau
MA, USA

On Sat, Jun 12, 2010 at 8:29 PM, Joe Mastroianni <joe@xxxxxxxxxxxxxx> wrote:

> Hi Gary!
> (Yes, NPT=NST....rented fingers...)
> Thanks for the advice.  I was thinking I would have to add another string
> of 18 caps, to bring it to 3 parallel strings for the SRSG (according to the
> Tesla Map Program I need ~27.7 nF), but if you suggest 40nf  I may try that
> - or close to that.  I have enough caps for 4 strings of 18 so I can give
> that a try.  I will be using a new secondary, same primary.  But then the
> topload has to change as you suggest.
> Any suggestion where I might find a spun aluminum toroid that's bigger?   I
> think there was a suggestion on this mailing list some time ago about Ross
> Engineering but there was another place was O.W. Landergren and then finally
> John Freau himself.   Do you know if these sources are still good?  I guess
> on Monday I can just start calling.
>
> Thanks!
> Joe
>
>
>
>
> On Jun 12, 2010, at 4:26 PM, Gary Lau wrote:
>
> > Hi Joe,
> >
> > NPT=NST??
> >
> > A couple things I want to mention.  Your toroid looks kind of small for a
> > 15/60 powered system.  My 15/60 coil uses a 7"x30" toroid, and every
> > increase in size resulted in longer sparks.  The down side is that while
> the
> > sparks got longer, they also got less frantic and bright, so that's a
> > tradeoff.
> >
> > You also mentioned using an SRSG.  It's vital to realize that you just
> can't
> > swap out a static gap with an SRSG.  Unless you also increase the cap uF
> > when going to an SRSG, you'll overvolt things considerably, or if you
> have
> > properly set safety gaps (a MUST-HAVE with any rotary gap), they'll fire
> > constantly.
> >
> > With my 15/60, I found the optimal SRSG cap value to be 0.04uF (at 60
> Hz).
> > This is larger than most folks use with a 15/60 & SRSG, but works well
> for
> > me.
> >
> > Of course if you change the cap size with the gap type, you'll also need
> to
> > change the primary or secondary or topload to keep things tuned, so it's
> not
> > possible to change only the gap and see if performance improves.  It
> really
> > involves a complete system makeover.  But it's a good time to consider
> > increasing primary and secondary inductance and topload size - all
> > beneficial things.
> >
> > Regards, Gary Lau
> > MA, USA
> >
> > On Sat, Jun 12, 2010 at 6:39 PM, Joe Mastroianni <joe@xxxxxxxxxxxxxx>
> wrote:
> >
> >> Same coil I showed last time.
> >> Added another bank of CDE 942C20K15 caps to bring total to 36.   Two
> >> parallel strings of 18.
> >> Upgraded the NPT to a 15/60.
> >> Spark activity is much more significant.  Where before I would only have
> >> sparks at the brass breakout rod, now they're everywhere.
> >> I think I'll try shining up the toroid to see if that changes the
> >> characteristics.  I'll also do a night shot for contrast.  The streamers
> are
> >> actually hitting the strike ring now, which they didn't before.
> >>
> >> Tuning had to change from the 15th turn of the 1/4" flat coil of
> >> refrigeration tubing to between the 11th and 12th.  I didn't do fine
> tuning
> >> yet.
> >>
> >> <http://yfrog.com/mjimg0083z>
> >>
> >> I have some components for the synch rotary SG, and other showing up
> this
> >> coming week.   We'll see how that works.
> >>
> >> Cheers,
> >>
> >> Joe_______________________________________________
> >> Tesla mailing list
> >> Tesla@xxxxxxxxxx
> >> http://www.pupman.com/mailman/listinfo/tesla
> >>
> > _______________________________________________
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