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Re: Resulting static after TC runs

Original poster: John Williams <jwilliams@xxxxxxx>

I read this list often but don't post to it for years on end.
So, I have been around I just don't talk a lot.
What causes the static build up is pretty simple but we
don't think about it much because after vacuum tubes, complex little
radio tubes and the like, and semi-conductors came along there
was no need to exploit it the effect commercially. So, people
don't think about it much these days.
A very long time ago a friend of mine found an antique tube.
A very large antique tube. It had a couple of electrodes in it and a small
pool of mercury.
Neither of us figured it out at the time, but it wasn't any sort of
a lamp. It was big and crude and ugly as all heck.
A long time after that I did find out what it was. It was a very early
form of rectifier, and to work it depended on he fact that ions of differing
mass travel at different speeds. This doesn't make for a great rectifier
but it did work well enough that it could be used to make ac current
dc enough to drive something like a street car. Brutal by todays standards,
but it worked.
By now most of you know what I am driving at. Tesla coils
produce loads of ionized air. The ions produced vary in mass and so
are accelerated in the field around the coil differently, resulting
in charge separation.
Bingo! Static.

        There is a book, long out of print I believe, published in 1941,
"Gaseous Conductors - Theory and Engineering Applications" by
James Dillon Cobine, Ph. D. that someone might be able to find
in a used book store if they really wanted to wade into this far enough
to drown.
        The second chapter is "Mobility of Gaseous Ions" and there
are descriptions there of how ions move in electric fields.
        So if there are folks out there who think I am stuffed clean
full of fresh blueberry muffins there is a reference for you to dig up.


        John Williams

On Feb 28, 2005, at 8:51 AM, Tesla list wrote:

Original poster: Steve Ward <steve.ward@xxxxxxxxx>

Hey guys,

I know all about secondary coils building up a net static charge, when
you grab onto it and lt gives you a good one ;-)  but has anyone
noticed the surrounding environment (floors, walls, ceiling)
developing a serious static charge?

Ever since i switched my DRSSTCs over to primary current feedback, ive
noticed that the coil charges up my floor to a good 5-8kv (estimating
by the sparks i can throw to nearby objects when standing in that
floor space after a TC run).  And tonight i ran my larger DRSSTC for
the first time on primary feedback... it was snapping out 42" sparks
at only 50% input (and 700A peak in the primary!!  cant wait to take
this thing outside!).  Anyway, i walk over to measure the spark
distance with my measuring tape, and while holding the tape up near
the target i get several (maybe 10) 1/4" sparks from the target to the
tape in my hand.  That's some impressive static build up!  What really
impressed me is that it just kept firing off the .25" sparks, about
twice a second.  There is also the pain of grabbing the primary clip
to tune, this static sure is getting annoying!  And i must also note
that the shocks i get from this static is seemingly more painful than
your typical static build up (my friend noticed this as well when he
came to see my coil a few weeks back).

So does anyone have an idea of whats going on here?  I seem to
remember hearing that its possible to get a diode effect with
differently shaped terminals?  But i still cant figure out why my tile
floor is accumulating so much charge.  Interestingly, i never noticed
this effect when running my coil with secondary feedback, but maybe a
simple environmental change explains it all (perhaps its dryer

Curious to see if anyone else has noticed this... its a first for me
and I've been playing with coils for, oh, 6 years now and quite
usually in this same location.


Steve Ward