Re: Dimensions of my flat spiral coil

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

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

> Can you briefly explain the "parasitic effect of the meter?"

The meter is designed to give a reading when connected to a pure
capacitor, but you are connecting it to a capacitor in parallel
with an inductor. What it will measure in this condition depends
on how the meter makes the measurement.

Something similar happens when you try to measure inductance. Any
real inductor, specially these large ones, have significant
"self-capacitance", or, behave more accurately as parallel
LC circuits. Inductance meters are designed to measure correctly
if the "self-capacitance" is low enough, essentially by making
the measuremet using low-frequency signals, that are not much
affected by the capacitance.

In principle, a capacitance meter using high-frequency signals
should be capable of measuring the "self-capacitance" of a coil.
But this would require frequencies above the resonance frequency
of the coil, and the measurement would be subject to many sources
of error. Conventional capacitance meters use low-frequency
signals only, in a variety of measurement methods.

Antonio Carlos M. de Queiroz