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Re: Micro coil earthing/smallest magnifier?

Original poster: "Dr. Duncan Cadd by way of Terry Fritz <twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>

Hi Matt!

>Yes, i have. I'm a fourteen year old and i built a TC out of scratch.
It is
>power by a 10kV 23ma OBIT and it has a 2 3/4" by 12" secondary. My
>ground was an 8" long wood spike driven in the ground. I then took a
>foot copper rod and sank that. The output increased by 2".
>So now i am getting a total of 5" sparks off this coil to a grounded
>I also noticed that the streamers took on a more opaque appearance
>rather than the skinny, flashy sparks that i got before.

It's interesting you also got a significant change in streamer
appearance, although going from a wood stake to a metal one doesn't
surprise me quite as much as going from a metal stake to a couple of
metal boxes.  The sparks off my micro-coil also changed appearance,
from rather thin, dim, crackly sparks to thicker, brighter more
flame-like sparks.

The secondary of this coil I originally wound around a year and a half
ago to try making a really small magnifier, but I never could get it
to work very well.  It doesn't like large toploads for some strange
reason; I've tried this with secondaries from 12"x3" to 5"x1,5" with
turns 300 to 1500, coupling coils from 2"x1,5" to 4"x2", toploads from
3/8" dia. to 4" dia. and even a mini-toroid from solid brass, with and
without breakout points - it doesn't want to play with any of those.
Though I can get four inch sparks to a grounded rod, there's no way it
will produce four inch sparks into the air, and these sparks are thin,
dim and crackly anyhow.  I'm beginning to think that induction coil
driven TCs have their own set of rules, probably starting with the
energy storage 0,5LI^2 in the induction coil primary.

So today I wound yet another coupling coil, around 3"x2" and gave the
secondary (1,125" x7,5", ~700t, 0,1mm wire) a one inch diameter drawer
knob topload.  Bingo!  Two inch+ bright, thick sparks like flames,
squeaking like the scraping together of expanded polystyrene foam!
This with 15W from the induction coil.  About the same performance as
using the secondary inductively coupled, perhaps a little better, but
at last, it works as a magnifier!  The setting of the spark gap across
the induction coil is really, really critical.  Open it more than the
"ideal" amount, and the sparks actually get shorter, thinner and

Is this the smallest magnifier to date?

Geek#1113 (G-1)