RE: Variable Capacitance and Inductance

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

Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>

Hi Jan,

>Yes, L and C do vary, if the surroundings of the place of measurement are
changed. If the surroundings remain absolutely fixed, exactly, L and C won't
change.

Thanks.  That's the point right there.  Inductance and capacitance are
affected by stellar activity, geomagnetic activity, house wiring, and the
abundance of metal in our society and even in the ground.  Atmospheric
conditions will affect the electrostatics of a coil and capacitor, but there
are many influences that affect inductance and capacitance.

The observations of Tesla and others on this list of variable inductance in
there coils is not necessarily the result of faulty equipment, measuring
techniques, or humidity.  It has taken a while to get to this point, but I
think we may be there.

When the environmental factors contributing to variable inductance and
capacity are acknowledged then that opens the doors to further knowledge in
our art of coiling.  There are certain designs of coils that are more
susceptible to environmental changes than others.  The combination flat
spiral and secondary coil that I use produces a fluctuation in inductance
readings between 5mH and 30mH each second when my house power is on.  Even
this fluctuation varies over time.  When I measure the inductance of a very
large flat spiral coil, the inductance meter won't work.  These observations
are not equipment malfunctions but measurements of real phenomenon that are
worthy of further study by coilers.

Based on the limited data I have collected so far, house current appears to
be the most influential factor that alters inductance and capacitance in a
dwelling.  When my combination coil is operating I see fluctuations in its
functioning as well.

>Here's an experiment for your (maybe for others too!):

This is a good suggestion.  I have also planned a similar experiment where a
capacitor and inductor would be stored in evacuated jars and measured for a
period of time.  This would eliminate the humidity and temperature factors.

Dave