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Magnifier notes

Subject:  Magnifier notes
  Date:   Thu, 17 Apr 1997 09:00:46 -0500 (CDT)
  From:   Bert Pool <bertpool-at-flash-dot-net>
    To:   tesla-at-pupman-dot-com


Wild Bill and I spend Wednesday finishing up our new magnifier driver
and
the winding of a new resonator coil (another future cannon shell.)

This new secondary is 16 inches in diameter, 37 inch winding length. 
Most
importantly, it uses TWO layers of wire wound one on top of the other. 
The
outer winding is 1/2 inch shorter in length to compensate for its
slightly
larger diameter.  The wire we used is 14 gauge high voltage test prod
wire
with 5 kv working voltage rating.  Each layer of wire is about 1100 feet
long.  We were very interested whether this "one on top of the other"
bifilar method would work.  It works very well, indeed!

Our new resonator coil is 8.44 inches in diameter, 24 inches long, 18
gauge
wire.  It is uncoated.  We started out with a 30 inch by 7 inch spun
aluminum toroid.  We have changed out our caps from two 0.06 ufd in a
series
equidrive configuration to two 0.03 ufd in series.  Our input power
requirements dropped to 1/2 of what we were running last test - now it's
40
- 45 amps input current.

Now the sparks.  We ended up tuning all the way to 9 turns (our maximum)
on
the primary.  Every time we moved out one more turn, the sparks got
longer.
We were getting consistent 6 to 7 foot sparks to an aluminum ladder, and
occasional 8 foot hits to the front of the garage.  We added a 40 inch
by
4.5 inch toroid on top of the spun toroid, and the sparks were even
better.
It was at this time that the heat of the resonator coil melted the hot
glue
on the bottom corona ring.  The resonator coil and both toroids suddenly
toppled off and fell.  Since this stuff was sitting atop a 6 foot tall
pvc
pipe and concrete was below, the results were tragic.  My homemade
toroid
ended on the bottom of the fall and took the brunt of the fall, and
mostly
protected Bill's $350 toroid - but his top did not get away completely
unscathed.  His top now has a shallow dent about 6 inches long with some
nasty scrapes.  It will sand smooth, but it shure hurts to see such a
beautiful top get whacked.  Oh well, it could have been worse.

Lessons:  Two layer driver secondaries work (at least with hv wire they
do).
Even 18 gauge coils get hot when you run them non-stop for 4 or 5
minutes.
Hot glue melts - use JB Weld on corona ring attachments on extra coils! 
We
also found that the metal garage door frame acted as an 18 inch wide
safety
gap on our driver secondary.  Whenever the resonator output struck the
transmission line, we'd get a flashover from the top of the secondary to
the
garage door, thus safely shunting the over-voltage to ground.  We're
thinking of making such a safety gap a standard practice in the future -
it
helps prevent secondary breakdowns.

We got excellent video (even caught the toroids starting to topple
over),
and I took a roll of stills.  I'm on vacation for two weeks, so the
pictures
will be a while a'waiting.  The many 8+ footers are a new record for us,
and
we're still pushing to get to 10+ feet.  This new driver is gonna get us
there, I believe.


Bert Pool
bertpool-at-flash-dot-net