Re: coupling coefficient

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

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

Tesla list wrote:
 >
 > Original poster: "Christoph Bohr by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <cb-at-luebke-lands.de>

 > I had my coupling adjusted when I had a 30nF primary cap. Will this be
 > still OK if I change to 60nF or more primary capacitance or will I have to
 > decrease coupling due to higher excitation with bigger bangsize?

The coupling coefficient depends only on the configuration of the coils.
With greater primary capacitance, you will need less primary inductance,
and this will change the coupling a bit due to the different geometry.
If the primary charging voltage is the same, the output voltage will
be bigger (about 1.4 times). If your secondary coil is insufficiently
insulated, this may cause "racing sparks", and you will have to
decrease the coupling. The racing sparks, I think, will eventually
disappear because with lower coupling the losses increase, the maximum
output voltage decreases, and the voltage gradient along the
secondary will be smaller.

Antonio Carlos M. de Queiroz