Re: status report

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "S&JY" <youngsters@xxxxxxxxxxxxxxx>

Justin,

I disagree with David's claim for the need of big (dangerous) filter caps.
You can choose the amount of AC ripple you are willing to tolerate on your
DC output (e.g. 10%), then calculate the filter cap based on the DC load
your setup will draw (e.g. 0.25 amp).  The equations and "how to" may be
found in the Power
Supply section of Radio Amateur's Handbooks.  You can get used ones from
Ebay and other used book dealers--lots of good info for coilers.

I run a DC coil that performs quite well,
and the filter cap is only 0.67 mF at 18 KV (which is still dangerous) made
up of 24 microwave oven caps in series-parallel.

That aside, DC resonant charging gives you a lot more "fun factor" because
you can control
break rate and power fairly independently.  But to get the most fun out of
DC, you need a rotary or triggered spark gap.  And if you
design your system right, you don't need to ballast your HV transformer.

I would not recommend using a NST to run a DC system.  NSTs are designed to
run mostly at lower voltages, once the gas filled (neon) lamp is conducting.
With a DC system, you are likely to be running your NST without a proper
load at times which will lead to insulation breakdown inside the NST.  Best
to go with MOTs or a Potential Transformer.  I use an oil immersed MOT
6-pack which works just
fine.
--Steve Y.

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Tuesday, December 27, 2005 6:17 PM
Subject: Re: statur report


> Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
>
> Justin,

>
> To build a DC Tesla system "right", you are going to need
> some really BIG filter capacitors! I'm talking like quarter
> shrinker/can crusher sized caps! Then of course you'll al-
> so need to make sure that you have an adequate inductive
> reactor to keep all of the filter cap(s)' energy from trying to
> flood the spark gap and damaging or destroying the other
> tank circuit components. 0.1 uFd isn't nearly enough capacitance
> for a FILTER cap for even a small DC resonant Tesla coil sys-
> tem. Think 10's of uFds. Others that aren't as numerically
> challenged as myself can run the numbers and formulae for
> you.
>
> Having said all of that, it should be quite apparent that a
> typical AC Tesla system is considerably simpler to build and
> you get about the same performance per input power, so
> why bother with the extra labor, time and co$t of building
> a DC system unless you just want to meet the challenge?
>
> David
>
> ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Tuesday, December 27, 2005 1:18 PM
> Subject: statur report
>
>
> >Original poster: Just Justin <rocketfuel@xxxxxxxxxxxxx>
> >
> >Greetings,
> >
> >After a long period of research, I've finally started building my
> >first coil.  I must say, I was inspired by Malcolm's speed and so
> >I've set my sights on having something to show my friends on New
> >Year's Eve.  It will go well with the fireworks and flamethrowers.
> >
> >Anyway, my first source of good information was Richie Burnett's
> >wonderful site, which made me want to go straight for a DC
> >resonant system right away.