RE: I'm a newbie coiler!

["Tesla list" <tesla@xxxxxxxxxx>]

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

Hi Zooch:

My comments interspersed:

> Original poster: "Steve Ziuchkovski" <smz@xxxxxxxxxxxxxxx>

> It's a Magnetek 15kv 30ma transfomer. The information on eBay says
> the part number is 721-111-400, and the label information is that
> it's a 120v, 60 Hz, 450VA, 30mA transformer. However, I can't find a
> datasheet on the net for it. Anyone have any information?

I've never seen a data sheet for an NST, but you already know everything
that one needs to.

> If my research and knowledge is correct, this baby puts out 15kv at
> 30ma, which comes out to 450w. Draws about 3.75 amps from the wall.
> If I short the secondary terminals together, nothing untowards will
> happen as long as the mains circuit can provide 3.75 amps without
> blowing breakers or fuses or melting the wiring at this rating, right?

It turns out that when an NST is running in a Tesla coil, it's very
possible for it to draw far in excess of its faceplate rated power.  My
15/60 NST pulls in excess of 20A!

> For my first project, I plan to hook this up for a Jacob's Ladder -
> effectively shorting the secondary. Any issues associated with this?

Nope - just good clean fun.

> I've read the safety sheet (at
> <http://www.pupman.com/safety.htm>www.pupman.com/safety.htm), but I
> know I'll be making a spark-gap transmitter. I live in an apartment
> complex and don't want to piss off my neighbors by making their TVs
> go whacky, causing them to drop cell-phone calls, and making their
> dog's bark. I also don't want to suffocate myself with ozone. But I
> also wont be running my Jacob's Ladder for hours on end.

I don't know that a Jacob's Ladder generates a lot of ozone, but I've
never run one very long.  A TC will generate much more.

You're in a difficult situation living in an apartment with TC
ambitions.  A TC WILL generate a significant amount of TV/phone/radio
interference, as well as just being acoustically loud, and there's no
way around any of that.  Getting a good RF ground may be difficult, and
that may make the interference problem worse.  My best suggestion is to
either focus on a small minicoil (very satisfying IMO), or find a friend
with a house and run it there.

>
> As far as the tesla coil plans go - I read an article at
>
<http://www.nutsvolts.com/PDF_Files/tesla.pdf>http://www.nutsvolts.com/P
DF_File
> s/tesla.pdf,
> and this seems like a pretty simple article for a pretty simple
> design. However, it's missing some details that I think I might like.
> Can someone point me to a better article or web site? I'd like to
> have some good specific guidelines, but something general enough that
> will let me play around a little depending on what is available
locally.

I see many things with that plan that differ from what's considered the
state of the art.  RFC's won't help and may make matters worse as far as
protecting the NST.  The positions of the cap and gap should be
reversed.  A home made cap for a 15kV NST will fail in short order if
made the way it described.  Setting the spark gap arbitrarily can toast
your NST and needs to be set with care.  My web site discusses these
topics at length, and also describes my minicoil.  See
www.laushaus.com/tesla  There's about a billion other Tesla sites as
well.

> I'd also like to be able to make some meaurements on the resulting
> hardware. Like I said, I've played around with electronics before,
> usually low-voltage stuff. I have experience with some embedded
> hardware/software, mostly with Atmel's line of microprocessors. I've
> done some stuff with this hardware like collecting measurements on
> temperatures, RTCs, logging the data to EEPROMS, and displaying stuff
> on LCDs/interfacing with computers over RS232. Where can I find
> information on measuring the frequencies/voltages/currents present in
> a tesla coil? How do I go about making HV probes and such, and
> overcoming the interference I'd be getting by having this circuitry
> in proximity to my tesla coil, when it's built? Or, for that matter,
> near my Jacob's Ladder as a starting point? Apparently, analog meters
> may be the way to go, but being able to collect digital samples to
> analyze seem to be a little more fun (and more accurate).

Forget about microprocessors with Tesla coils, unless you're on the
bleeding edge building a programmable solid state coil.  Analog meters
are next to useless since any AC meter assumes a continuous sine-wave
waveform, and TC's just don't do that.  You can learn a lot just by
hanging an oscilloscope probe in the vicinity of an operating TC - it
will capacitively couple to the HV output and will show you the true
nature and waveform of the output.  But quantifying the actual output
voltage just isn't done - we don't know how!  Instead we quantify
performance by measuring spark length, and understanding that there's
not even a rough correlation between spark length and the actual output
voltage.

You can make resonant frequency measurements of the primary and
secondary circuits using a function generator and scope, with the coil
NOT OPERATING.  Terry Fritz designed and documented an optically
isolated voltage/current scope probe that is useful in measuring
operating parameters of a TC, but it's not a trivial project, and not at
all necessary if you just want to get the coil to work.

>
> It looks like my little e-mail here is not so little anymore.
>
> Well, my name is "Zooch", and I love electronics - and electricity.
>
> Steve "Zooch" Ziuchkovski

Have fun!

Gary Lau
MA, USA