Gary,
Sounds like a pretty scary adventure veering off from the plans I have
which indicate simple things such as just adding more capacitance. I think
what I will do first is get a working single NST tesla coil first
(15kv/60mA) and using the 2nd NST as a backup incase the first ever gets
fried. If it looks like the design is stable than perhaps later on I will
take on a 2 NST new design. Its been 35 years since I built my first and so
much great development has happened and new ideas learned by the smart
people here and other places in the Tesla Coil world. Thanks again for your
insight and the others here that make this such a fun hobby.
Tim
On Fri, Feb 20, 2015 at 8:02 PM, Gary Lau <glau1024@xxxxxxxxx> wrote:
> 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
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