Re: VERY HIGH BPS at 6kw!

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

Original poster: "Malcolm Watts by way of Terry Fritz <teslalist-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Steve,

On 8 May 2003, at 21:46, Tesla list wrote:

 > Original poster: "Steven Ward by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>
 >
 > Hi all,
 >
 > I built a 4 pack MOT supply and it works ok.  There is no limiting besides
 > the wires that come from the 240V outlet.  But thats not so
 > important.  This coil is running with a static sucker gap, and only about
 > .0475uf of capacitance.  In this scenario, the arcs SCREAM!  It sounds like
 > 1000bps or maybe more!  The sparks are WHITE and hot when the arc to the
 > ground.  But, the coil is dissapointing with only 6-6.5 feet of
 > spark.  Also, the sparks will start downward, and end up vertical in the
 > air!  This is common for high BPS i guess.

It is common where there is effectively continuous heating of the air
channel.

   But, i want about 9 feet or
 > more, so i need to lower the bps.  So, im thinking of making the cap in the
 > .09 to .1uf range!  I know, this is HUGE.

I wouldn't regard it as such. I've happily used caps of that size in
the past.

   Right now, im using 13 turns on
 > the primary (7"ID  23"OD
 > .25" cu) with a 6.5"x36" 24awg secondary and a 4.5"x30" toroid.  I know
 > that with that huge cap, i will only use a small fraction of those primary
 > turns.  But, just how BAD is this scenario?  Im basically limited to 9kv or
 > so.  I do plan to eventaully (if a 5 turn primary works good for example)
 > make the primary from .5" copper or something bigger.  How bad will the
 > caps be stressed?  I have 3 strings of the geek type MMC caps, maybe 4 or 5
 > with the larger cap values (those nearing .1uf).  Are there any coils
 > similar to mine out there?  IF so, what is the typical output?  Id like 10
 > feet if possible.

It is *not* the number of turns that count (how many times have I
said this before??) - it is the *inductance* that matters and if you
are concerned about very high primary currents and consequent gap
losses, then build a much lower frequency coil to get Xp (Lp) up. I
think your biggest problem is going to be a voltage limitation with
your relatively short secondary as Ep climbs.

Malcolm