RE: [TCML] Photos of my coil.

["Lau, Gary" <Gary.Lau@xxxxxx>]

The only capacitor calculator I found at DeepfriedNeon suggests using the mains-resonant value - .0053uF for your case.  I would suggest using the chart at http://www.classictesla.com/download/mmc_cap_chart.pdf, which takes into account the concept of LTR and the type of gap.  

Be sure to address my concerns about your safety gap spacing, and the number of MOV devices.  These are show-stoppers!

As far as adding vanes to your RSG rotor to increase airflow and improve quenching, I don't think to.  There is already plenty of airflow by virtue of the rotor's movement.  The quenching is what it is; I don't think going from lots of airflow to lots plus a little more will make any difference.  It may be helpful to supplement the cooling of the stationary electrodes, but this should be accomplished with heat-sinking - a larger chunk of metal to draw the heat into, and not using something that melts.  See mine at http://www.laushaus.com/tesla/sync_gap.htm.  Acrylic is not a good choice for the rotor or stationary electrode supports.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of austin feathers
> Sent: Monday, August 10, 2009 1:31 AM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Photos of my coil.
> 
> Thanks Gary,
> 
> I reran the numbers through the calculator at www.deepfriedneon.com, and it
> came up with .0127 microfarrads, so I Should probably use 3/4 of the string
> as you advised. I heard that the cap value of the tank should be twice the
> rated voltage of the transformer, but I've also heard that the polypropylene
> film Cornell Dubilier capacitors I'm using have been proven very resilliant.
> I think I'll combine the advice and say that 22kV will be ok :). Also, I've
> been wondering if the equations at the deepfriedneon site are designed with
> predetermined reference to the static gap detailed in the site's
> construction page, and if I should use the site at all.
> 
> Thanks!
> 
> Austin
> 
> On Sun, Aug 9, 2009 at 4:01 PM, Lau, Gary <Gary.Lau@xxxxxx> wrote:
> 
> > Hi Austin,
> >
> > I think I see a problem.  Your cap is .0093uF, and you are using a 15/30
> > NST at 60Hz.  Your cap is a healthy value if you were using a static gap,
> > but I think you're using a 120BPS sync RSG.  Using a sync RSG requires a
> > much higher cap value than if you were using a static gap.  If you use a
> > static gap-sized cap, it will charge to a too-high voltage, and, well, you
> > know the rest...
> >
> > The recommended value for your situation is .0136uF (
> > http://www.classictesla.com/download/mmc_cap_chart.pdf ), though I prefer
> > to lean to the high side - maybe .015uf or so.  You maybe could reduce your
> > cap string from 16 to 11 units, resulting in a .0136uF/22kV cap.  But there
> > would be very little margin for overvoltage and you would need to carefully
> > set your safety gap and not go further.  But it would certainly last longer
> > than your last NST!
> >
> > When using any kind of RSG, having a properly set safety gap in parallel
> > with the RSG is an absolute requirement.  It's difficult to say for sure,
> > but it looks like the safety gap on your Terry filter is set rather wide.
> >  As the electrode geometry will always be different, one must only set the
> > gap width experimentally.  So don't copy what I say, but my Terry filter (
> > http://www.laushaus.com/tesla/protection.htm ) safety gap is 0.17" on each
> > side, with a 15kV NST running 140VAC in.  I suspect you had to open it up to
> > keep it from firing?
> >
> > I also noticed that your Terry filter has 7 MOV devices per side.  With a
> > 15kV NST, the required number is 8 per side.  Are these the same Panasonic
> > ERZ-V10D182 devices that Terry originally specified?  Using fewer than the
> > recommended number _should_ result in smoking them!
> >
> > Regards, Gary Lau
> > MA, USA
> >
> > > -----Original Message-----
> > > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> > > Behalf Of austin feathers
> > > Sent: Sunday, August 09, 2009 1:37 AM
> > > To: tesla@xxxxxxxxxx
> > > Subject: [TCML] Photos of my coil.
> > >
> >  > Hey all! It's Austin. Heres my flikr account, along with photos of the
> > coil
> > > I'm constructing. I'm an aspiring coiler and would very much welcome any
> > > critical observations or queries as to the design and how it may be
> > > improved.
> > >
> > > http://www.flickr.com/photos/thedangerousnerd/sets/72157621985544942/
> > >
> > > Also, I've been pondering the death of my first 15Kv 30 milliamp
> > > Franceformer neon sign transformer. I'll admit that I didnt have the
> > terry
> > > filter grounded, but the autopsy (trying to draw an arc from either pole)
> > > revealed that either the primary was done for, or that both secondary
> > > windings failed, in that if one of the secondary coils were intact, I
> > should
> > > (?) be able to get 7,500v from a surviving pole to the transformer case.
> > > Any idea what happened, or what I might do to protect a new transformer?
> > >
> > > Thanks!
> > >
> > > Austin
> > >
> > > P.S. I'm looking to procure anywhere from a 10-25 amp variac for main
> > > voltage controll, as well as a 15Kv 60milliamp NST. Should I just throw
> > > money at it? Or do you guys have some kindof high-voltage fairy that
> > stops
> > > by with loads of surplus components...
> >
> >  _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> >
> 
> 
> 
> --
> Austin
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