[TCML] Climbing Arcs

Thu May 29 06:55:43 MDT 2008

Hi Frank,

Wow, a 1920's vintage x-ray tranformer! I would ask if it has PCBs
but unless it has been refilled at some time during the 1930's to the
late 1970's (which is certianly possible), then it probably is NOT PCB
filled, as PCBs were not made until sometime in the 1930's.

I used to own several x-ray transformers but they did tend to take up
a bunch of my limited space so now I am down to one 150 kVp, 600
mA unit that tips the scales in the 500 to 600 lb. range. I have modi-
fied it by removing the internal diodes, which is necessary if you intend
to run a JL with it. I have also removed the factory Federal female HV
access ports and replaced them with the porcelain HV bushings from
a 14.4 kV pig. It looks so much more sinister with those bushings
sticking up and they make a handy connection point for the rails for
a Jacob's ladder. You can see a short, poor quality video clip of it driving
a wicked JL at: http://www.youtube.com/watch?v=0dLTEOM3qQc

David Rieben

----- Original Message ----- 
From: "Frank" <fxrays at hughes.net>
To: "Tesla Coil Mailing List" <tesla at pupman.com>
Sent: Tuesday, May 27, 2008 10:58 PM
Subject: Re: [TCML] Climbing Arcs

>I have a 20's vintage X ray transformer, oil filled and weighs about 300 
>pounds. It has a built in reactance coil. It runs on 220V
> On 110, I could produce a very HOT Jacob's ladder with the peak being 
> about 10" apart and the inverted V or the arc was over 8" tall.
> I used coat hanger rods and it made a beautiful display.
> I tried some larger dia tubing and the arc would not travel the full 
> length. A lot of times it would stop part way up and the arc would remain 
> stationary. I had to fan it with some paper to get the arc moving again.
>
> Conduit is not a good choice for another reason, it is usually galvanized 
> and the arc will burn the coating releasing zinc fumes which are quite 
> toxic.
> Frank
>
> At 08:40 AM 5/27/2008 -0700, you wrote:
>>Tony:
>>
>>Do NOT use the 3/4 inch conduit tubing.  Use 1/8th inch stainless
>>steel rods.  The smaller dia rods strike easier and do not conduct the
>>heat away as fast as the 3/4 inch conduit.  Result is a better
>>climbing arc the performs well without re-striking all the time.
>>
>>Dr. Resonance
>>
>>
>>
>>On 5/27/08, Bert Hickman <bert.hickman at aquila.net> wrote:
>> > Hi Tony,
>> >
>> > Some suggestions:
>> >
>> > 1. Use a wide "V" to more rapidly spread the arc. The higher the 
>> > current
>> > the wider the end gap should be
>> > 2. Use inductive ballasting for best performance
>> > 3. Use smooth rails to avoid incandescent "hot spots" that will cause
>> > the arc roots to temporarily hang in one spot. I'd recommend using 3/4"
>> > hard copper pipe or non-magnetic stainless steel tubing. Periodically
>> > remove any oxide buildup. I suspect the oxidation of the galvanizing 
>> > may
>> > a major part of the problem you're seeing.
>> > 4. Enclose on 4 sides to reduce disruption by air currents. Leave top
>> > AND bottom portion open to permit vertical air flow. Be sure to leave
>> > plenty of clearance on either side of the gap, especially for a higher
>> > current ladder.
>> > 5. For grins, try connecting a small (500 - 1000 pF) HV doorknob cap
>> > across the gap to make for "snappier" performance at start and at long
>> > arc lengths.
>> >
>> > Good luck,
>> >
>> > Bert
>> >
>> > Sfxneon at aol.com wrote:
>> >> Hi Ken,
>> >>
>> >> You're right, the arc climbs because it's hotter and less dense than 
>> >> the
>> >> surrounding air. I've had no problem making the small NST powered ones
>> >> work, but
>> >> at higher currents the middle of the arc tends to rise faster than the
>> >> ends.
>> >> It  grows in length but hardly ever makes it to the top of the rails, 
>> >> even
>> >>
>> >> when set  close. It seems to get stuck along the way and doesn't want 
>> >> to
>> >> climb
>> >> smoothly.
>> >>
>> >> Does anyone know if the smoothness of the rail's surface or the zinc
>> >> coating
>> >> would have anything to do with it?
>> >>
>> >> Thanks,
>> >>
>> >> Tony G
>> >>
>> >> In a message dated 5/27/2008 8:47:52 A.M. Central Daylight  Time,
>> >> kwillison2 at cox.net writes:
>> >>
>> >> I never built a really large one. I have however observed that any 
>> >> air
>> >> movement across the ladder will disrupt the arc. Conducted some
>> >> experiments
>> >> tilting the electrodes from vertical it would not work beyond 30 
>> >> degrees.
>> >> The curve of the arc remained vertical while the electrodes were 
>> >> tilted.
>> >> I
>> >> surmised that heat causes the arc to rise and heat raises  vertically 
>> >> so
>> >> won't work when it passes about 30  degrees.
>> >> Ken
>> >>
>> >> -----Original Message-----
>> >> From:  tesla-bounces at pupman.com [mailto:tesla-bounces at pupman.com] On
>> >> Behalf
>> >> Of  Sfxneon at aol.com
>> >> Sent: Tuesday, May 27, 2008 12:10 AM
>> >> To:  tesla at pupman.com
>> >> Subject: [TCML] Climbing Arcs
>> >>
>> >> Hi All,
>> >>
>> >> I have a  spare 12.5 kVA/20 kV bombarding transformer and sliding 
>> >> choke
>> >> with
>> >>
>> >> which I'm building a large Jacob's ladder using 3/4" x 10' EMT 
>> >> conduit.
>> >> It
>> >> works reasonably well, but the arc tends to rise up the  rails too 
>> >> slowly
>> >> and
>> >> the
>> >> middle of the arc outruns the ends, resulting in  a restart before it
>> >> reaches
>> >> the  top. I've adjusted the angle of the  rails from near parallel to
>> >> about
>> >> 18" apart  at the top, without much  success.
>> >>
>> >> Does anyone know how to tweak the performance of a big climbing  arc 
>> >> so
>> >> that
>> >>
>> >> it will climb to the top of the rails more often? I'm  guessing that
>> >> increasing
>> >> the air convection around the arc would help it  to climb, so will
>> >> inclosing
>> >> it in a tall clear tube or box make a  difference? Does the material 
>> >> that
>> >> the
>> >> rails are made of have any  effect? How about the ballasting  of the
>> >> transformer, as far as  inductive or resistive, etc?
>> >>
>> >> Thanks,
>> >>
>> >> Tony Greer
>> >>
>> >>
>> >>
>> >>
>> >> **************Get trade secrets for amazing burgers. Watch "Cooking 
>> >> with
>> >> Tyler Florence" on AOL Food.
>> >> (http://food.aol.com/tyler-florence?video=4&?NCID=aolfod00030000000002)
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>> >
>> >
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