RE: SIZE of RF chokes?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Sorry, what I said was less than clear unless you've been down that
road.

There are two slightly different circuit configurations for a Tesla
coil.  Spark performance is identical between them, but one is much less
stressful to the NST than the other.  There are no concise names for the
two configurations, so...

The tank circuit - that portion of the primary circuit that high current
flows through - is a series loop consisting of the capacitor, primary
coil, and spark gap.  The power supply - the NST secondary or the output
of a protection network - may be connected to the tank circuit is either
of two places.

1) Connecting the power supply across the capacitor is bad, as the full
magnitude of the tank circuit oscillation is applied to the NST
secondary.

2) Connecting the power supply across the main gap is good, as the tank
circuit only has (for the most part) RF present while the gap is
conducting.  If the power supply is wired across the gap, it will be
shorted out during the time interval when most of the RF is present,
protecting the power supply.

Regards, Gary Lau

> Original poster: "JT Bowles" <jasotb@xxxxxxxxxxx>
>
> "Also, make sure your
> main spark gap is fed by your protection network, rather than your
cap. "
>
> What the...?   I dont know what that means.
>
>
>
> >From: "Tesla list" <tesla@xxxxxxxxxx>
> >To: tesla@xxxxxxxxxx
> >Subject: RE: SIZE of RF chokes? Date: Wed, 16 Nov 2005 18:23:37 -0700
> >
> >Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>
> >
> >The current wisdom concerning chokes in NST protection circuits is to
> >not use them at all.  Using just series-chokes without bypass caps
> >accomplishes nothing, and using chokes with bypass caps to form a
> >low-pass network creates new resonances just as or perhaps more
> >hazardous as the RF from the tank circuit.  Instead, use an R-C
low-pass
> >network.  Please see a detailed discussion of this topic on my web
site
> >- http://www.laushaus.com/tesla/protection.htm.  Also, make sure your
> >main spark gap is fed by your protection network, rather than your
cap.
> >
> >I had all kind of trouble with stuff arcing to where it shouldn't
when I
> >used air-core chokes, so your safety gap firings may be related to
this,
> >or maybe not.  But there's no point to creating a second tier of
safety
> >gaps.
> >
> >Regards, Gary Lau
> >MA, USA
> >
> >
> > > Original poster: "JT Bowles" <jasotb@xxxxxxxxxxx>
> > >
> > > I have read .1 to .3 millihenries.
> > > On one of your threads, I just read .03 millihenries (30 micro)
> > >
> > >
> > > PLEASE tell me- are my choke the right size.
> > >
> > > -I have a 12,000 30ma neon, 60Hz
> > > -Close to resonant capacitor (supposed to be 6.66nF, but its
7.8nF)
> > >
> > >
> > > * My chokes currently are set up on BOTH sides of my HV circuit
(both
> > > outputs of xformer)
> > > * Each choke measures 7.4uH
> > > * Both chokes are 80 turns of 19gauge wire, on an aircore form,
.25 X
> >1.5" long
> > >
> > > USING THIS...RANDOM..INFORMATION, CAN YOU TELL ME WHAT SIZE
> OF
> > > CHOKES
> > > I NEED, AND ARE MINE THE RIGHT SIZE ALREADY.
> > >
>
>-----------------------------------------------------------------------
-
> >---------------------------------------
> > > --------------------
> > > Plus: my safety gap fires frequently, but not too much. When it
fires
> > > it becomes the sparkgap.
> > > *So, should i make a SECOND safety gap after the first?
> > > *Or, is it ok to fire as the sparkgap. In otherwords, when it acts
as
> > > sparkgap, will overvoltage occur in my neon?
> > >
> > >
> > > my safety sircuit is set up as:
> > >
> > > transformer - connects to safety gap - connects to 7.4uH air
chokes
> > > on both sides - rest of circuit
> > >
> > > I KNOW I TYPED A LOT, BUT I NEED PEOPLE TO ANSWER ALL, OR MOST
> OF
> > > MY
> > > QUESTIONS. PLEASE ANSWER MY WHOLE EMAIL.
> > >
> > > Thanks.
> > >
> > > _
> > >
>