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Re: [TCML] Jacob's Ladder
Hello Group,
My Jacob's ladder is very simple it uses an O.R.B.I.T.
and welding rod mounted in ceramic electric fence insulators. I believe it's
a 10/25 orbit, it gets warm during long runs but usually by then the rods
are smokin' hot. Many years ago I would light a cigarette in the arc as a
stunt.I don't recommend that but hey back then my teen age friends and I
would consider it manly to see who could hang on to the hi tension wire from
a model A
ignition coil and light 4 foot flourescent bulbs with the electricty going
thru the body.(That one stings a bit) Oh the nutty things we do growing up.
He hee.. here's to reminising Best Wishes to all ... Binny...
----- Original Message -----
From: "Weinhold Shannon L" <Shannon.L.Weinhold@xxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, February 02, 2011 4:11 PM
Subject: RE: [TCML] Jacob's Ladder
No intentions of creating controversy....just my experience...
I've had good luck using 1/4" copper tubing for Jacob's ladder electrodes.
In my design I utilized 1.5" long ceramic tube insulators (the kind they
used in houses way back when to insulate wires in the attic) to get through
the wood. I crimped the end of the copper tubing to make it fit into the
wire hole of a heavy duty connector and bent the tubing into an s shape to
route it to the end of the NST. I connected these directly to the NST.
This made the electrodes pretty stiff. The 1/4" tubing actually seems to
work very well. Bends to shape fairly easily, but requires enough force that
it won't bend out of shape once its set.
I've never been able to get a Jacob's ladder to function with a cap across
the electrodes. It just makes an evil buzz sound.
Sorry Scott, I have to disagree on the voltage vs. current thing. Yes, you
can extend a lower voltage arc of considerable current out a larger distance
than a higher voltage and lower current, but the lower the voltage, the
harder it is to get the arc self started across the same distance as is
possible with a higher voltage. Which is why we use level shifters (voltage
multipliers) with microwave oven transformers. Getting the spark gap to self
start across a reasonable spark gap space (with a MOT without the shifting)
is quite difficult, and then getting it to quench is damn near impossible
once its started.
A Gabriel electrode helps with getting the arc to self start (google it),
but really I've found the 15/30 to be an absolute minimum to obtaining a
reliable ladder, and a 12/60 is really optimum if you want something
impressive, and you'll still need the Gabriel electrode to make it work
reliably.
If there are safety concerns, get an acrylic (or polycarbonate or pyrex,
ect) tube with an inside diameter larger than the span of the electrodes and
long enough that the electrodes cannot be touched easily, and mount this
over the electrodes. This actually adds an echo/amplification to the sound
and adds to the cool factor.
Spirals are tricky, and the main thing to consider is that a Jacobs ladder
works by continuously moving the arc into the super heated (and there for
more conductive) air space directly above the current position of the arc,
so the spiral need to be going up more so than out to keep this convection
process in play. Good luck with the spiral thing. Its tricky.
Shannon Weinhold
"Our virtues and our failings are inseparable, like force and matter.
When they separate, man is no more."
~Nikola Tesla
-----Original Message-----
From: Gary Lau [mailto:glau1024@xxxxxxxxx]
Sent: Tuesday, February 01, 2011 8:08 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Jacob's Ladder
Capacitors are NOT typically used in a Jacobs Ladder. Putting a cap in
parallel with the NST and electrodes will make for a much louder sound, and
it may also result in a brighter arc. However, this circuit can easily
result in the destruction of the NST if the cap value is remotely near the
mains-resonant value, because the gap on a JL is by definition, wide open.
I have seen a very impressive display that creates VERY long arcs using a
ballasted pole pig and a series-connected capacitor. I suspect that this
would also result in over-voltage damage to an NST so I wouldn't recommend
this either.
I would recommend against using copper tubing for the electrodes. You need
the electrodes to be straight and rigid, and copper tubing is neither.
Instead, go to Home Depot and get some 3 ft 1/8" steel rods, in the hardware
aisle.
For "special effects", I've found that common table salt applied to
moistened electrodes results in the brightest colors - even more-so than
strontium salts. And skewered baby carrots yield a surprisingly bright and
colorful arc.
Regards, Gary Lau
MA, USA
On Tue, Feb 1, 2011 at 11:39 AM, David Steinberg <david.steinberg@xxxxxxxxxx
wrote:
I have a 9kv / 30mA NST, some ¼" copper tubing, 7 CDE 942 caps
(0.15mfd 2,000 v) and high voltage wire left over from building my tesla
coil.
I'm looking to construct a good jacob's ladder. Here are my design
parameters:
1. The voltage / current should be sub-lethal. That being said, I
think the 9kv transformer may not be powerful enough. I would
consider building a voltage multiplier, etc., if that would help. Or
switching to a
15 kv NST.
2. I'd like to use my left-overs, but I don't mind buying a few new
things;
3. A simple coat-hanger V-design is out of the question. It must be
interesting - perhaps a spiral, perhaps something different and
interesting;
I am looking for any and all ideas and / or designs. Should I go ac or
dc?
Is there a simple way to boast the power of the 9kv transformer, or
should I go with something else? Anyone have a great and novel
design?
Thanks,
David
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