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Sort-of-First-Light :)
Yup, me again :) Here's a story of my night tonight, and my
sort-of-first light of my coil. (it's resonant a *little* bit anyway!)
It's well worth reading simply for a good laugh, and I hope everybody gets a
kick out of it :)
But before you all criticise *too* much, remember we all started *somewhere!
Now, on with the show!
Well, I've been reading and reading and reading for quite awhile on this.
Gone through most of the pupman archives, and tons 'o webpages. I've been
planning my 4" coil, and have got most of my specs down on it. I've
scrounged and gotten myself a half-dozen NST's.
Now, I've been saving for my caps for my MMC and magnet wire. We all know
that it takes money to do this *right*, and sometimes the green stuff is a
bit too hard to come by. I love coiling, but I also can't pass up a great
deal like I got. I was offered an exhaust setup for my motorcycle for $150,
and it's about a $300 setup. I jumped on it, and my MMC is a bit further
away now...Such is the way of the world.
But all is not lost! There's plenty of caps out there for the making!
Now I've already had a little (read messy) sucess with saltwater caps. 2
bottles of cooking oil and a huge mess from a dropped bottle (that friggin
oil is *slick!*) later, I decided there *had* to be a better way. Enter the
rolled PE cap.
Well, I don't exactly have PE lying around my house in the quantity nor
quality I need for a good cap. So..I improvised. Big black trashbags :)
Yup, you read it right. The big ones I use in the garage. I saw 'em and
figured, "hey, why not?" So I grabbed my trusty roll of tinfoil, a
handfull of bags, and headed inside for a reasonably clean floor. I wiped
down the floor and proceeded to roll my own cap. I knows the bags are 4 mil
bags, waaaaay to thin for the 90 mil I need for a *real* cap...but I've got
this cute little 4kv30ma unit...so I figure I'll make one for it. Well, my
machine was tied up, so I decided to use the whole bag and let the
capacitance sort itself out ;) It's just an experiment anywho. Here's what
I did.
I laid out 4 bags, each bag was folded twice lengthwise from the factory,
giving me 8 layers of 4 mil. 128 mil alltogether, that was 10" wide by
about 50" long. I strung out a strip of aluminum foil (cheapie Kash&Karry
stuff), about 50" long also. I folded it in half, and overlapped the edge
of the bags so I got about a 2" border all around it.
I put down 4 more bags, and another sheet of foil, overlapping the opposite
end. First rolling attempt, it all pretty much slid all over and looked
really crappy. Unrolled it, and thought for a minute. I taped one whole end
up. Each sheet to the one on top of it, and *then* rolled it. Worked like
a champ :) All the time I'm doing this, I've got my 85 pound Doberman going
spastic chasing a bug around the living room. Luckily the cap escaped
trampling, but I'm positive it got some hair in it. Probably *not* a good
thing.
Well, the cap was rolled, ziptied, and had 2 big 'ole wire sticking out of
it. Looked really, *really* silly :) Well, I had a cap, and a xformer, now
I needed a secondary and primary. And a spark gap. First, I decided to
make my gap.
I've already got the copper pipe for my ground rod, just haven't sunk it
yet. I cut 2 3" pieces off of it, so I've got my 1.5" diax3" long static
gap. I ground a chunk out 1 end of each pipe, about 1/4" on the end. I
grabbed a sheet of Lexan, and my trusty can 'o Bond-o. I mixed up a small
batch, made a 1/4" thick puddle on the lexan, and plunked both pieces of
pipe in it. Slipped a hacksaw blade in the middle, and zip-tied 'em in
place to set for awhile.
My secondary...ah...This was fun. I ripped into an old wall-wart (plugin
xformer), and after de-coring it (nothing like an apple!), I got to the
goods. Wire, and lots of it. I wound the secondary on a piece of 1"x7" PVC
pipe. The wire was .017" by my micrometer, and I wound about 5.5" of it.
My computer was still busy, so I had no idea what it *should* have been, and
lost count of the turns somewhere around 500, so I just wound to twice what
I already had, and secured the wire. For my primary, I used 22awg hookup
wire (hey, it can't be taking *too* much current off a 4kv30ma unit,eh?)
About 15 turns on a film cannister did the trick for that. Now, my spark
gap. I removed the zipties and hacksaw blade, and the bond-o was pretty
much set (I mix it hot and work fast). Now, let's see..parts list
here...secondary, primary, gap, cap, and xformer. Wow...looks like I'm set
to watch it all smoke. Not bad for 4 hours of work here. So I hooked it
up. Set my saftey gap on the NST at 3/8", laughing as I figured it'd never
fire. More on that later :) Hooked up my cap, gap, and positioned the
coils. Well, I used my shelves in the garage as a ground. They're screwed
right to the wall with about 20 screws, and they're metal. Plenty of bare
metal on 'em. Attached the bottom of the secondary to 'em, and
double-checked it all. Plugged in my power cord, and threw my switch.
The arc gap buzzed like a rabid chainsaw, and threw off a *lot* of pretty
white-blue light. Hmm. Nothing out of the top of the secondary though.
Nuts. So I cut it off, unplugged it and shorted my cap. No sparks, no
nothing. *sigh* Another experiment failed. Ahwell. Then I thought about
the coil, and remembered the old "bipolar secondary" I hooked up a wire
from the base of the coil and positioned it about 1/2" from the top, plugged
it in, and threw the switch. I laughed like a loon when I got that dinky
little 1/2" spark!
Now ya got to understand..this is the first tesla for me. And the fact
that I was making even that dinky little 1/2" spark from sheer resonance was
really neat. Well, I watched that for a minute or so, then thought about my
cap. Jeez!!! I cut power and unplugged it all. I shorted the cap (paranoid
'bout that!), and felt the temp. Ambient. Puzzled, I decided to swap in a
12kv-at-30ma unit instead of the little 4kv unit. I hooked it up instead,
reset my saftey gap, and fired it all off. Louder brapping from the SG, and
got a 3/4" spark. Woohoo!!! Well, I ran that for about 3 minutes, and
checked the cap again. Not even warm.
Now I was getting suspicious, and decided to *smoke test* my cap. I
cleared the table,grabbed my extinguisher, and removed my coil from the
setup. I ran a saftey gap of 1.5", and a sparkgap of 3". I just moved my
clip from the other side of my SG and moved it to 3" from the hot side of
the SG. I backed off a little, plugged it all in, and threw the switch. On
the 12kv unit. Man, oh man. Loud doesn't even descibe it. It mades a
chainsaw sound lame. I watched it through a welding lens (momma didn't raise
no 'foo!), and it's actually quite pretty! Then the saftey gap fired.
Scared me half out of my mind, and I cut it off immediately. Then I started
laughing even more. I cut it back on, and ran it for about 4 minutes
straight, the saftey gap firing maybe 5 times a minute. After the neighbors
came over and complained, I cut it off and checked the cap. Barely warm to
the touch. It was 8:45, so I decided to call it a night.
Now, can someone tell me *why* that cap didn't evaporate under that kinda
abuse, when there's *no* oil in it, and plenty of air, dog dander, some
lint, and whatnot? But even better, I got a spark! WOOHOO! of course the
spark gap was much more impressive, but i sparked nonetheless! Yeah!!
Well, that's the story of my lame-little first coil ;) Total time
start-to-finish, 4 hours. Total money invested...probably less than $10.
Fun I had doing it..more than I've had in a long time!!! Now I'm definately
gonna get that 4" coil running. It was a definately learning experience for
me. I know know a *lot* more about my tank circuit and how it works.
Secondary, priamries, I see how they get along and how the resonance makes
the voltage get so high. Know the importance of a good ground too :) Not
to mention ear protection though! If I can get my camera dusted off, I'll
grab a pic of that *silly* looking trash-bag cap for ya'll to laugh at. I
don't recomment building one, but it is a hoot to see :)
Safe coilin' all, and smile! It could be worse!
Sundog - A Man On A Mission....now, if only I knew what it was!