RE: Terry filter alternates?

["Tesla list" <tesla@xxxxxxxxxx>]

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

Hi Ed:

An R-C filter without the C's just isn't a filter and will do little to
shunt HF transients. Also, a total of 6K in series with your NST will
consume a lot of power.

Since you are running a close-to-resonant sized cap with a sync RSG, I
am concerned that your peak charging voltage may be hazardous.  I'm
repeating my measurements below with my 15/60 NST and various cap sizes,
and it shows how the bang voltage (BV),  increases with decreasing Cp.
I was afraid to try below .02uF, but it's easy to extrapolate where your
.015uF might fall.  Also, the voltages I recorded were the bang
voltages, not the peak charging voltages, which were considerably
higher.

Perhaps your 6K of resistance helped current limit the charging and
prevent destruction?

Measured at 140VAC in:
Cp	BV	W
.02uF	24.4kV	714W
.03uF	21.9kV	863W
.04uF	19.6kV	922W
.05uF	17.1kV	877W

Regards, Gary

> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Wednesday, December 08, 2004 2:33 PM
> To: tesla@xxxxxxxxxx
> Subject: Re: Terry filter alternates?
>
> Original poster: Esondrmn@xxxxxxx
>
> Snip,
>
> I use 3,000 ohm 25 watt resistors in series with each high voltage
lead on
> my 3.0" coil with a 15 kv 60 ma transformer - and they do get hot.  I
use
> only these resistors and safety gaps for transformer protection.
Haven't
> had any problems with this so far.  Looking for some wood to knock on.
>
> Ed Sonderman
>
>
> In a message dated 12/7/04 6:25:01 PM Pacific Standard Time,
> tesla@xxxxxxxxxx writes:
>
> >Err, Except im not using 21kv, using 15kv, and they only will be
charged to
> >7.5kv each, hence we get: 300pf and about 1watt at 120BPS
> >not sure where your math went wrong there, even at 21kv its only
7.938watts
> >at 120bps. + the 14.4 watts of his 120ma nst still not close to
29watts.
> >And im only operateing at 30ma, hence 0.9 watts disipated in the
resistors.
> >Hence by the sound of it, for a 30ma 15kv coil, 5watt resistors could
even
> >do in a pinch (assumeing the voltage did'nt expload them, hence why
id
> >probley use 10 watt resistors, mabey 2 in series)
> >
> >
> > >So we now have 43.4 watts in the resistors.  At 100 watts, they
have a
> > >300C temp rise.  At 43 watts, they are cooking at 155C  Darn
toasty!!
> > >
> > >Problem is the normal full rated temp for the power resistors is
stunning
> > >300C!!  So we massively over rate them to keep the temperatures
sane.
> > >Originally I used much smaller resistors, but everyone whined that
they
> > >were getting supper hot.  So I upped the size of the resistors like
4X and
> > >no more complaints ;-))
> > >
> > >Cheers,
> > >
> > >     Terry
>
>
>