Re: How to Tune a Flat Spiral Coil

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Dave,

Tesla list wrote:

> Original poster: "David Thomson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>
>
> Today I fired up the trifilar coil and tried tapping the primary at 2.5
> turns instead of the full 3.5 turns.  The frequency did not change and the
> voltage went through the roof.  Actually, it snapped pretty strong through
> the 1/4 inch Plexiglas and 1/4" hot glue.  I'm going to put another 1/4" of
> Plexiglas under the primary for a total of 1/2" of Plexiglas and 1/4" of hot
> glue.  The dielectric strength should be well over 500,000V.  And if this
> doesn't work, I'll add another layer.

Two things here:
First, this sounds like it's "out of tune", similar to the situation on a
helical where an out of
tune coil causes racing sparks. Which to me indicates that it "is tuning".
It's simply out of tune.
The secondary should still ring at it's own frequency. If I'm mistaken,
hopefully someone will
correct me.

Second, I'm amazed you arc'd through the 1/4" plexiglas. There "must" be
some very high voltages
present. Curious, I would imagine the arcs point of origin through the
Plexiglas was near the outer
windings?

Take care,
Bart