A Christmas Story For Coilers

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Robert by way of Terry Fritz <twftesla-at-qwest-dot-net>" <obiwan1186-at-sunflower-dot-com>


got this of of Stefan Kuge's website. hope nobody minds i'm posting it. 


A Christmas Story for Coilers
by Fr. Tom McGahee 
(Originally written Christmas of 1998) 
(Slightly Modified for Christmas, 1999) 

The story begins innocently enough... Meanwhile, out in the garage, Bill the
Frankfurter was busily lashing together his latest concoction: In keeping with
the Christmas Spirit, Bill was building a rather large Christmas Decoration for
the front yard. To the uninitiated it looked simply like a large aluminum
Christmas tree mounted on a pedestal of some sort. In reality, the aluminum
Christmas tree was merely the Topload on Bill's latest Tesla Coil. Bill knew
full well that the geometry of the tree did not really lend itself well to
being an EFFICICIENT topload. But that was all-right. Bill was more interested
in shock value than he was in efficiency. Actually, the pedestal was the
"extra" coil of Bill's experimental Magnifier Tesla Coil. According to his
calculations the "extra" coil should be capable of throwing arcs at least 6
feet long. One of these days, if he could manage to scrape up the necessary
cash, he would try building one of those as yet untried polymorphic toroid
structures designed by that guy who was advertising plans for them on the Tesla
List. But not today. 

He chuckled to himself as he struggled to move the "extra" coil and Christmas
tree topload out of the garage and onto the front lawn. His wife was currently
curled up in front of the fireplace with a romance book and two cats. Bill
hated cats, but for the sake of his wife he tolerated their presence in his
home. Bill strapped the coil/tree assembly to the top of the little American
Flyer sled, and wrestled it into position on the front lawn. The final position
was about 7 feet away from the shoveled walkway that led from the street to his
front door. Bill always used the side door, but he had In-Laws coming over
tonight, and *they* always used the Front Door. He figured the 6 foot arcs
would be hurled mostly upward, and there would be no chance of the arcs
actually coming any where near the In-Laws as they came down the little
shoveled path that he had prepared. 

He carefully positioned a couple of dozen old polyethylene buckets to hold the
transmission line, which was several lengths of 1/2 inch copper tubing that he
had brazed together. He giggled to himself deliriously as he fastened the
transmission line in place and attached it to the base of the "extra" coil.
Then he attached the other end of the transmission line to the anti-corona ring
of his secondary coil. 

The secondary coil consisted of a single layer of high voltage test prod wire
wrapped in a solenoid fashion around a fair-sized plastic garbage can. The test
prod wire was "on loan" from Bill's employer. The employer was unaware of this
fact, but Bill appreciated his generosity all the same. The garbage can was a
slightly used Rubber-Maid garbage can that Bill had swiped from the kitchen
earlier in the day. The garage was permeated with the odor of aging tuna fish.
The plastic garbage can was nestled inside a piece of slightly damp cardboard
sonotube that was several inches larger in diameter than the garbage can. Bill
had "borrowed" the sonotube from a construction site a few blocks away that was
not very heavily guarded. One of these days he would return it. If he managed
to remember, of course... The primary consisted of several turns of heavy
battery cable that Bill had found laying around in the back of one of his
buddies' trucks. (All of Bill's buddies drive trucks...) 

Most of the high voltage capacitors were homebrew poly caps in sections of PVC
pipe and under mineral oil (actually an off-brand of cattle laxative that he
had seen mentioned by Gary Weaver on the Tesla List.) Not being able to find
any decent clear poly, Bill had managed to scrape up a mixture of
"construction" grade poly (that had lots of interesting things imbedded in it),
and some smooth and shiny BLACK poly that he thought might work well, despite
his fleeting concern that it might contain large quantities of carbon in the
form of lampblack. What the heck, what did he have to lose by trying??? 

Dozens of these capacitors were wired in series - parallel to achieve the
required voltage and capacitance rating. Just a few days before, he had
discovered a mistake in his calculations and had realized that he still needed
more capacitance. Remembering a series of posts on the Tesla List about MMC and
EMMC caps, Bill had decided to try his hand at making EDEMMCB caps. (Extremely
Dangerous Extended Monolithic Modular Capacitor Banks) Let's see, now, he was
sure that Terry Fritz or one of those guys had posted something about being
able to run them at something like 3 times their rated DC voltage. So with his
14.4KV One Eared Pole Pig he would need about a 4.8KV rating on the caps. Being
a somewhat conservative kind of a guy (at least when it comes to things
electrical), he decided to round that up to a 5KV DC rating. He smiled broadly
at the thought of all the extra margin of safety he had engineered into this
EDEMMCB capacitor. 

He had purchased one hundred .1 microfarad 500 volt DC off-brand snubber caps
at the local Radio Shack for a buck a piece. What the heck. It was Christmas.
He could afford to splurge a little. He didn't have any of that printed circuit
board stuff to mount the capacitors onto, so he just spot soldered strings of
ten capacitors together. He kept the leads the full length and just spot
soldered the very ends of the capacitors together. That way if a capacitor were
to accidentally fail he could just snip off the very end and turn them back
into Radio Shack for a full refund. The only problem with leaving the leads so
long was that the strings of capacitors were quite long. Fifty inches to be
exact. He wasn't about to waste any precious money on high megohm resistors, so
there were no bleeder resistors across any of the caps. The ten strings of
capacitors were laid out side by side on the concrete floor. As was his custom,
Bill lashed all the capacitor strings together using Radio Shack clip leads. 

Imagine Bill's consternation when he measured the total capacitance of his poly
caps and EDEMMCB capacitor only to discover that he was still off by .01001
microfarad from the magic capacitor value that TESLAC had spit out. 

Not wanting to spend any more money and time on poly caps or more strings of
EDEMMCB caps, he decided to revert to making the tried and true Beer Bottle
Caps. He had tried making Soda Bottle Caps once, but they were not nearly so
much *fun* to make as Beer Bottle Caps. 

Bill had invited a couple dozen of his closest friends over for a Bring Your
Own Booze - Beer Bash. His wife finally busted up the party at 4 AM Sunday
morning. Bill emptied out whatever beer still remained in the bottles (I leave
it to your own imagination to figure out just how he did this). After many many
trips to the bathroom he finally had all the empty beer bottles he needed.
There were a fair number of aluminum cans as well. These he put in the plastic
garbage bag in the kitchen. While his wife wasn't looking he stole all the
aluminum foil and corn oil and salt that he could find and proceeded to build a
couple of tub-fulls of beer bottle caps, which he then wired into the existing
capacitor grid using his few remaining Radio Shack clip leads. 

The spark gap was an old circular saw blade that was missing a couple of teeth.
Why bother to pay big bucks to that Wingate guy for a precision built and
properly balanced tungsten gapped rotary spark gap with G-10 fiberglass wheel
when you could make your own for next to nothing? Bill's own rotary spark gap
was powered by an ancient single phase AC motor that Bill had scrounged from
the local dump for a few bucks. The motor and circular saw blade were connected
via a belt and pulley arrangement, since the shaft of the AC motor was somewhat
bent, and could not reliably direct-drive the saw blade. As it was, when the
spark gap motor was powered on, the wooden base to which the entire Spark Gap
assembly was bolted would shake all over the place and make an awful racket.
Bill had jerry-rigged a device that allowed him to vary the phasing on the
spark gap by rotating the motor by pulling on a four foot long two-by-four.
Bill had wanted to use a ten-foot-pole, but Malcolm Watts told him that nobody
would want to come near it with a ten-foot pole. That seems to have convinced
him. 

Looking through the archives, Bill had found a posting by John Freau on how to
convert small AC motors into fully synchronous motors. Oblivious to the fact
that the conversion pertained only to SMALL AC motors, Bill modified his motor
anyhow, and found that after filing away large chunks of his rotor that the
modification only made his motor lopsided. Now it REALLY jumped around when he
turned on the power. So he held the rotary spark gap assembly wooden base plate
as still as he could by temporarily holding it down with a couple of old lawn
mower engines that he had hanging around. He made a mental note to drop John a
nasty note telling him how useless his modification had been. 

Back a few feet from the spark gap was the one eared pole pig. Thick high
voltage cables snaked across the floor from the Pig to the Spark Gap and the
rest of the Tesla Coil. Not wanting to cut the cables, (which he had borrowed
from work without asking) Bill had left each cable its original length of fifty
feet. 

The pig was fed a diet of 220 VAC from a 100 amp service line. Now, the pole
piggie was only rated at 10KVA, but Bill had read somewhere on the List that
you could actually push a pig to two or three times its rated power capacity if
you kept the run short, (so that you didn't boil off all the oil). Bill planned
to test out this theory tonight. 

Now, Bill SHOULD have had a number of things that he didn't. Such as common
sense, an ON/OFF switch, and adequate fuses. Bill just couldn't bring himself
to pay good money for something that was designed to self-destruct. Instead of
fuses he had placed large metal bolts in the fuse holders. Much more robust,
don't you think?? 

Being something of a cheapskate, Bill had decided not to bother with installing
a silly little thing like an ON/OFF switch, because the guy at the dump wanted
more than two bucks for the ones he had in the big box marked "Electrical
Stuff". He knew that he needed something to limit the current to the pole pig,
so he decided to wire a couple of defective toaster ovens and a couple of
strings of Christmas tree bulbs in *parallel* with the primary of the pole pig.
He could have SWORN that he had read a post somewhere (maybe on the Tesla-2
List) about putting some sort of a load in series or parallel or something or
other with the transformer primary. 

Bill knew that a variac was really a "must", but he didn't have one. He was
originally going to use a 5 amp Triac that was on sale at Radio Shack, but when
he got there they were all out. But then he remembered having read a post that
seemed to imply that you could modify a three phase AC motor to act as some
kind of a variable transformer. Sneaking into the dump under cover of darkness,
he liberated a 400 pound three phase AC motor that had once seen service in an
office building as the elevator motor. Luckily for him he owned a truck with a
crane attached. Heh heh. A few whacks with an axe in just the right places and
he had de-commisioned one set of windings. He knew he only needed two. But
which two? He hoped it was the two that still remained. He welded two metal
stubs to the casing and then welded a three foot length of one inch diameter
solid steel rod to the rotor shaft. Now the motor shaft could only turn 90
degrees. 

It was still a minute or two before the In-Laws were scheduled to arrive. One
last check and Bill was ready for an operational test. He turned on the rotary
spark gap motor. Whump! Whump! Whump! Whump! Whump
WhumpWHUMPwhumpawhumpawumpawupa... Yes, the spark gap assembly was a bit, uh,
vibrational, but seemed to be holding together OK. Bill lined the plug up with
the socket (remember, he had no ON/OFF switch), and rammed the plug into the
socket. BZZZZSHHHT! The spark gap lit up with bright actinic light and would
have fried Bill's eyeballs in no time at all if not for the fact that Bill
(always safety conscious) had quickly put on a pair of welding goggles. Now he
could look at the spark gap arc with impunity. Which he did. Unfortunately, the
goggles were so dark that that was ALL that Bill could see. 

Carefully shielding his eyes with his left hand, he used his right hand to
gingerly lift the goggles and look at the Christmas tree on the front lawn. 

Outside, the Christmas tree came to life with a pale glow of pink and blue
corona that fuzzed out for about two feet. But no arcs. No streamers. What a
bummer! He stuffed another wad of cotton in each ear so that he could think
again, and taking a deep breath of the ozone-soaked air, he groped his way over
towards the modified three phase motor. Grabbing a hold of the metal rod, he
strained to change the angle of the rotor. Suddenly a forest of fierce white
arcs as thick as his arm broke out between the primary and the secondary. DARN!


He released the control rod. TWANG!!!! The rod slammed itself into the short
stub that acted as a stop. Bill yanked the plug out of the socket. This was not
an easy task, as the plug was sort of welded into the socket. But a few good
whacks with a monkey wrench and the plug came loose. The only sound was the
whappawhappawhapa of the rotary gap assembly, and the insistent buzzing that
was only in Bill's ears. DARN! The secondary was arcing to the primary. Maybe
if he added a capacitive load to the secondary he could get this sucker to stop
arcing. He looked around for something... anything... to use as a capacitive
load. His eyes came to rest on the leering sharp-toothed smile of his butane
tank work of art, the Halloween Tank-O-Lantern. To amuse the neighbors and
anyone else foolish enough to approach his house at Halloween, he had fashioned
a gruesome Tank-O-Lantern by using a cutting torch to fashion leering eyes and
drooling teeth from the once-smooth surface of the butane tank. The various
burn marks from the cutting torch operations made the tank look even more
sinister when the light played on it just right. 

Grabbing the Tank-O-Lantern, he managed to get it to sit on top of the existing
anti-corona ring. It wobbled a bit, but what the heck. 

For the second time that evening, Bill rammed the plug into the socket. Again
the spark gap burst into life. The horrendous roar of the spark gap beat
against his ears as he grabbed the control rod and pulled. A fierce blue corona
outlined the eyes and teeth of the leering Tank-O-Lantern, and as he gleefully
peeked out from under the welding goggles, Bill could plainly see that
beautiful two to three foot arcs were issuing forth from the branches of the
aluminum Christmas tree. Not bad. The system was obviously a little out of
tune, and he didn't have much more time before the In-Laws would arrive, so he
would just have to run it the way it was. But he wanted the tree to look a bit
more Christmas-sy so he whacked the plug with the monkey wrench again and
turned off the high voltage. Then he made a quick surreptitious trip to the
attic and got some really awful Christmas ornaments, (the ones that his In-Laws
had given him and his wife years ago), and used them to decorate the tree. 

Unknown to Bill, while he was out decorating the tree, his wife came out to the
garage with a bag full of garbage that she didn't want in her kitchen for her
parents to see. Looking around in the garage she spied what she knew was a
plastic garbage can sitting inside what looked like a cardboard container of
some kind. Seeing no other garbage container around, she decided to dump the
load of trash into the plastic garbage can. So she did. And with interesting
results. 

Bill was totally unaware that the coupling and inductance of his coil had been
changed slightly by the addition of various beer cans and tuna fish containers
that had been dumped into the core of his beloved experimental Magnifier Coil. 

The addition of the gaudy glass Christmas tree ornaments had little effect on
the capacitance of the Christmas Tree Topload, but Bill's last-minute addition
of a large copper toilet ball to the very *top* of the tree had changed the
isotropic capacitance of the total topload just enough that the "extra" coil
and topload were in perfect tune. 

When Bill saw his In-Laws exit their car and begin their trip down the shoveled
walkway that led within a few feet of the Christmas Coil, he stationed himself
next to the power outlet and waited until they were at just the right spot. 

His face twitched nervously, and he made a strange gurgling sound as he waited
anxiously for his In-Laws to reach the perfect spot. And then they were there. 

Gleefully he jammed the plug into the socket and then ran excitedly over to the
control rod. Little beads of sweat broke out on his forehead as he grasped the
rod firmly with both hands and pulled madly back on the control rod. 

Meanwhile, inside the garbage can secondary, RF induction heating was taking
place on the cat food tin cans. The heat caused the garbage to shift suddenly,
and in that instant a wonderful serendipity took place. For a few fleeting
cycles, PERFECT resonance was achieved! Megawatts of energy happily surged back
and forth in the slipshod tank circuit of the amazing Christmas Coil. Phase
angles slipped past one another invisibly and fell in-synch. Due to a couple of
missing teeth on the makeshift rotary spark gap's circular saw blade the caps
ceased to fire for a moment, and the capacitor bank experienced an Anomalous
Resonant Rise. An instant later the excessive voltage caused a particularly
massive dump of energy into the primary circuit at precisely the right phase
angle, and the resulting surge in energy passed from the base of the wildly
glowing Tank-O- Lantern down the copper tubing transmission line, which looked
as though it were ringed with fire. The transmission line was just exactly the
right length to allow the electrical wave travelling down it to slam into the
base of the "extra" coil precisely at a zero voltage, MAX current node. Richard
Hull would have been proud. The "extra" coil and the Christmas Tree Topload
with round copper toilet ball were exactly matched to the impedance required,
and the massive driving force of megawatts of resonant energy caused the
"extra" coil to react like a spring that had been hit hard with a hammer. The
resulting jump in energy caused the voltage at the Christmas Tree to exceed the
breakdown voltage of the winter air. With a mad, screeching KaBOOOM the air
broke down, and a single solitary streamer launched itself into the cold night
air. Up, UP, *UP* it surged, sending a seething, writhing, liquid bolt of pure
white electricity stabbing through the darkness. Then, seeking the path of
least resistance, it arched over and began its lethal descent. Escaping the
intense electrostatic forces that existed at the surface of the aluminum tree,
the mighty bolt of man-made lightning swerved around and headed straight for
the nearest conductive object it could find!!! 

The In-Laws would have been toasted alive were it not for the one object that
caught the Arc's attention. Beyond the In-Laws, a good twenty feet from where
the Lightning Bolt had launched itself from the infamous Copper Toilet Ball,
was an old fashioned lamp post. It put out a dim but somewhat cheery quantity
of light that seemed to beckon to the Wayward Lightning Bolt. Like a giant
white arm, the lightning bolt swerved around from its upward climb and slammed
full force into the cheery lamp post. 

PHHHHHHHT! KABLAMMMMM! Like a gigantic flash lamp the lightning bolt lit up the
night with an instant of blinding whiteness and a deafening BLAM that
reverberated in the In-Law's ears long after their knees had stopped shaking.
Where the mighty arc hit, the metal of the lamp-post went incandescent and
exploded into a shower of hot sparks that rained through the air and burnt
their way through the snow. 

The momentary surge of primary current was too much for the EDEMMCB capacitor
strings. One moment they were as cool as the night air, then the next instant
they exploded like 100 Chinese firecrackers. When the EDEMMCB caps exploded
this placed too much of an electrical burden on the other capacitors in the
system. First the Beer Bottle caps shattered and sent shards of glass whizzing
in all directions. Then the once-sturdy home-made rolled caps exploded like a
bunch of defective cannon. They all burst at once and spewed hot liquid
laxative throughout the garage, and all over poor Bill, who was already feeling
pretty sh***y as it was. 

A flash of light. A moment of raw, awesome beauty, a might explosion, and then
DARKNESS as all the electricity for blocks around ceased to flow. 

It is a Christmas that Bill will always remember. It is a Christmas that his
wife and In-Laws will never let him forget. 


***** This is just a story. Any resemblance to any persons living or dead named
Bill is merely coincidental. 
    * As the author of this tale I want to say that the story is not meant
to be
    a plan for how to build your own Arcstarter -er- I mean, Magnifier Coil. 
    * The theory contained herein is only partially believeable, and is not
    meant to be a factual accounting of what actually happens in a Tesla Coil. 
    * This is not an endorsement of Radio Shack or any of their products. 
    * Cat lovers will please refrain from sending nasty e-mails to either Bill
    or myself. 
    * Plans for the Christmas Coil may be made available if enough persons are
    interested. I should mention that the plans are purely experimental, which
    is why I will only be charging a token $25 for the plans. 
    * I hope that all of you enjoy this little romp in the spirit in which it
    was written. I hope that none of those mentioned by name or otherwise
    implicated in the plot take offense at what has been written. 
    * I wrote it especially for my good friend (at least he WAS my good
friend),
    Bill the Arcstarter Pollack. But, as the disclaimer said, it is not
    actually ABOUT him. Even though he does hate cats and builds
    Tank-O-Lanterns, and dabbles in Tesla Coils. This story is just about a
    Bill who happens to be an awful lot LIKE Bill Pollack. The real Bill would
    *never* borrow anything from work without asking. He is beyond reproach. He
    is my friend. 
Written by Fr. Tom McGahee