Re: eddy current with secondary coil

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

Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 


Richard Hull (TCBOR) did a lot of research in this area, and I believe his
conclusion was that it was more effective for output spark length to have
the highest inductance possible so the spacewound is not the way to go for
long sparks.  Perhaps if Rich stills monitors the List he could add some
perspective here.

Lower capacitance, spacewound does have it's place in very large coils that
want to obtain a high voltage however they also achieve high inductance by
using very large secondary dia. coils to offset the spacewound effect.

Most coil in the range of 2 inch dia thru 24 inch dia. achieve the best
output spark length (notice I didn't say voltage here) with many turns and
high inductance.  We usually shoot for around 1,400 turns on small and
medium size coils and around 1,000 turns for our larger coils (10 ft plus
sparklength).

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913
 >  >
 >  > If the proximity effect of the secondary wires is causing higher eddy
 >  > currents within the wire, increasing reactance at high frequency, then
it
 >  > would make sence to space the turns out on the secondary form so that
more
 >  > energy will flow though the wire, which suggests higher output. Though
this
 >  > can't be true since close turns is what is required ?
 >  >
 >  > Chris
 >
 > Closewound is not a requirement. For a given wiregauge and form
 > length, you end up with a higher inductance and lower operating
 > frequency which is why most do it. You can think of a closewound coil
 > as being a spacewound one wound with thicker wire. From my
 > observations of running both types of secondary, spacewound is a
 > cheaper and lighter way to build a coil with about the same Q and
 > running frequency (i.e. the spacewound coil simply uses thinner wire
 > than the closewound one but uses the same winding pitch (turns/in).
 >
 > Malcolm
 >
 >
 >