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Re: If correct, this will change everything!!



Original poster: "Steve Ward" <steve.ward-at-gmail-dot-com> 

Your gonna get a lot response on this one Terry ;-),

My thoughts.  It seems that you have basically designed a DRSSTC with
a rather high surge impedance compared with the secondaries resonant
frequency.  65nF tank cap almost sounds normal compared to my first
DRSSTC that used 75nf, but my system works at 140khz while yours is
designed for merely 40khz!!

Now here is sort of an oddity i have noticed with DRSSTCs to date.  My
systems always prefer smaller tank capacitors and more cycles to drive
the resonator, while Jimmy's original DRSSTC used a HUGE tank
capacitor (.6uF!) and many less cycles by comparison.  When i tried
larger tank caps on my coil, the efficiency dropped off and i could
not achieve the great spark lengths i had seen with the smaller C.
*Same thing happened on my big DRSSTC!*  I used a 360nF cap on the big
coil for most of its life time, but there was a period where i tried
450nF.  It resulted in shorter sparks (maybe 9.5' compared to
11.some').  Also, i lost quite a few IGBTs that way as well.

Anyway, i plan to take a look at your simulation file some more and
try modifying the driving method (you have notches in your
waveforms... we typically go for no notch now).  Jimmy's first DRSSTC
setup had notches too  because he drove the coil between the 2 split
frequencies, but eventually he started driving the whole thing at the
lower split and got even better performance.  I want to see how your
sim reacts to this.

 >
 > Of course, if I made some giant boo boo, forget I ever brought it up ;-))

Hehe, well not sure what to make of it yet.  We still dont know what
the best way to drive these things is yet.  Some methods seem to work
very well while others just flop.  I might have to make an absurdly
fat secondary with small wire to test out your idea ;-).  In fact, im
open to suggestions on what types of combinations i should try as far
as operating frequency, L to C ratios of both primary AND secondary
circuits.  Ive been looking for something new to do for awhile now
;-).

Steve.

 >
 > Cheers,
 >
 >        Terry
 >
 >