For the longest sparks, a Larger Than Resonant cap is recommended. The MMC
design chart recommends for a 15/120 60 Hz NST w/ static gap, a .03uF cap,
so for 15/135, you could even go a bit higher. Now LTR isn't the law, and
one may in fact deliberately choose a STR cap, as it will have a different
character of spark - shorter but brighter and more dynamic.
Regards, Gary Lau
MA, USA
On Fri, Dec 22, 2017 at 3:56 PM, dennis otmaskin <dotmaskin@xxxxxxxxx>
wrote:
> Thanks Ian for your reply! What you say is encouraging to hear. If you
> don't mind, I have one more question...
>
> Java TC indicates, for my 15/135 NST, that Resonant Cap Size would be
> 0.0239uF. I understand that bad things happen when using resonant cap
> size. So I'm trying to decide on whether to use a 0.03uF cap or a .015uF.
> I've got one of each. The .03 cap is pretty close to the indicated .0358
> LTR Cap Size for a static gap. On the other hand if I plug the .015 cap
> into Java TC, it shows a dramatically greater rate of Breaks Per Second and
> possibly a few more inches of spark length. My question is is there any
> potential problem with resonant rise with the .015 cap. I.e., is the .015
> cap value far enough from the resonant cap size to be safe?
>
> Thanks again for your help, Dennis
>
> On Thu, Dec 21, 2017 at 11:55 PM, Ian McLean <austesla@xxxxxxxxxxxxxx>
> wrote:
>
> > Hi Dennis,
> >
> > If you have proper RCD¹s installed, it is unlikely you will trip a 15A
> > circuit with 18A at least for the sort of runs lengths you do on a Tesla
> > coil.
> >
> > I regularly ruin my tube coil at between 30A-40A from a wall socket. The
> > RCD is only 20A, but it has never tripped even with a 2 minute run.
> >
> > Cheers,
> > Ian
> >
> > On 22/12/17, 2:40 pm, "Tesla on behalf of dennis otmaskin"
> > <tesla-bounces@xxxxxxxxxx on behalf of dotmaskin@xxxxxxxxx> wrote:
> >
> > >Hi I'm hoping someone from the list can offer advice some advice and
> > >suggestions. I am replacing the 15/60 NST on my current static gap coil
> > >with a de-potted NST with some shunts removed so that it puts out
> 15000v @
> > >135mA.
> > >
> > >Running different designs on Javascript Coil Designer, I'm finding that
> > >the
> > >Effective Input Current (current draw?) runs over 18 rms amps. My wall
> > >outlets in the garage are all 15 amp. So if I'm understanding this
> > >correctly, it looks like I would be constantly tripping the circuit
> > >breaker
> > >when running the coil at full variac voltage. I've run different cap
> > >sizes
> > >through Java TC but cant seem to get around the 18 amp draw.
> > >
> > >To get the current draw to just below 15 amps, I would have to dial the
> > >variac down to 106 volts which would reduce the spark length
> > >substantially. I'm thinking that I am pretty much stuck with a systems
> > >that is limited to 106 volt input. Do you think this is the case? I'm
> > >hoping that I don't have to rewire my garage outlets for 20 amps just
> for
> > >my coil. Any suggestions would be most appreciated.
> > >
> > >Thanks, Dennis
> > >_______________________________________________
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> >
> >
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> >
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