The only reason to have transformers be identical is a matter of
aesthetics. As long as the output voltage is remotely similar, one can mix
France, Jefferson, whatever, flavors of NST's, if the phasing is correct,
and you'll know immediately if it's wrong. It's _nice_ to have them
identical but functionally unnecessary.
> There would be a lot more changes than just caps and gaps.
I would like to amplify the above point. Assuming you want to do
everything needed to extract the maximum arc length from the additional
power at your disposal, repeat over and over - Bigger is Better. You'll
want a larger top load, and you'll want a taller secondary to space the top
load farther from the primary to avoid strikes to it. The larger top load
and secondary will require a significantly larger primary, not just another
couple of turns. I ended up building a 2-layer primary to keep
the dimensions sane. Higher inductances and lower frequencies are all good!
Also, a 15/120 power supply is probably going to push the limits of what a
static gap can handle. You didn't mention what you're planning for a gap
but you might wish to consider a rotary. I highly recommend the propeller
gap configuration - http://www.laushaus.com/tesla/sync_gap.htm If you're
thinking about a synchronous rotary, the capacitor size needs to be much
higher than for a static gap, and will require comparably more primary
inductance.
And, a 15/120 power supply is going to pull a LOT of juice from the wall -
you'll want to make sure you have an adequate PFC capacitor to minimize
current draw. My single 15/60 pulls in excess of 20A with a sync rotary
and 240uF of PFC caps.
Bottom line - you should plan from day 1 what the final configuration is
going to be - you'll not be able to go back and forth with 1 or 2 NST's.
Regards, Gary Lau
MA, USA
On Fri, Feb 20, 2015 at 1:32 PM, Timothy Gilmore <tdg8934@xxxxxxxxx> wrote:
> Great videos on Phasing (both parts 1 and 2). I will watch those again when
> ready to set up.
>
> On Fri, Feb 20, 2015 at 9:36 AM, John Paul Grippa <pupman@xxxxxxxxxxxx>
> wrote:
>
> > There is a great video from the Geek Group on YouTube that explains how
> > this works extremely well. It will also give some good tips on how to
> > ensure proper phasing. Check it out!
> > https://www.youtube.com/watch?v=KSlQjw9OPG4
> >
> >
> > > Date: Fri, 20 Feb 2015 08:26:17 -0600
> > > From: tdg8934@xxxxxxxxx
> > > To: tesla@xxxxxxxxxx
> > > Subject: [TCML] Dual identical FRANCE neon sign transformers (15000v
> > 60mA each) in parallel
> > >
> > > I currently have a France NST at 15kv 60mA and built a nice jacobs
> ladder
> > > with it. Yesterday on eBay I found what looks to be identical model NST
> > for
> > > a good price (no GFI). From what I have read about NST phasing, having
> > > identical NSTs don't require testing the HV outputs and I should be
> able
> > to
> > > connect them up in parallel identically using the same sides. What a
> > jacobs
> > > ladder at 120mA would be! Anyway I'm assuming that I should start
> > building
> > > my tesla coil with 1 NST and when it works add the next NST in parallel
> > and
> > > double the capacitors and change the tap on the primary. Does this
> sound
> > > like all I would need to do?
> > >
> > > Thanks - Tim
> > > _______________________________________________
> > > Tesla mailing list
> > > Tesla@xxxxxxxxxx
> > > http://www.pupman.com/mailman/listinfo/tesla
> >
> > _______________________________________________
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> >
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