Re: space winding

["Ed Phillips" <evp-at-pacbell-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Tesla list wrote:
> 
> Original poster: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
> 
> Marc -
> 
> Log Dec has to do with how fast the dampened wave of the operating Tesla
> coil decreases. A larger Log Dec means the wave reduces much faster. In the
> days of spark radio transmitters a low Log Dec was desirable because this
> gave a clearer signal and was easier to read. It was not until the invention
> of the vacuum tube that zero Log Decs were possible and voice and video
> could be transmitted by the radio signal (carrier wave). However, low Log
> Decs are not desirable for Tesla coils because the long ring times means
> inefficient coils. Much more can be found about Log Decs in old radio books.
> 
> Pi is the ratio of the circumference to the radius of a circle. Pi is a
> constant and always equals 3.1416 for all circles. It is interesting to note
> that Log Dec times Q factor equals a constant or 3.1416 for all true Tesla
> coils. So-called tube Tesla coils equal zero Log Dec times Q factor equals
> zero.
> 
> John Couture

	To be more specific, the logarithmic decrement is the natural logarithm
of the ratio of two successive peaks of a waveform.  (Ratio of higher
peak to lower/later one.)  It is also one half the ratio of peaks two
peaks apart, one third of the ratio of peaks three peaks apart, etc. 
The effective Q of the circuit is Pi/decrement. For example, if the
ratio of two successive peaks is 1.1, the natural or Naperian logarithm
is about 0.1, and the effective Q is 3.1416/0.1 or 32.  If you look at
the waveform of your secondary discharge and try to estimate the Q you
can decide whether or not the unloaded Q (Q without discharge) makes
much difference or not.

	By the way, if the above ratio is less than about 0.2, the decrement is
about equal to the ratio minus 1.

Ed