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Re: tesla virgin no more ! but need help



Original poster: "steven hyman" <steve502-at-bellsouth-dot-net> 

thanks
based on some of these replies I will rework My MMC today
if best capacitance -at- 50k ohm impedance is .0085uf
and 18/19 1600vt cap per string will meet voltage requirements  -at- 15kv x
2.5=37.5kv

then one string 17  caps .15 uf /1600 vt
total capacitance .0088/ total voltage 27.2kv

whether I use 17/18/or19 caps per string
I should only use 1 string to better meet capacitance requirements   Right
??????


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, February 06, 2004 10:04 AM
Subject: Re: tesla virgin no more ! but need help


 > Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>
 >
 >
 > The math goes:
 >
 > A 15 kV, 30 mA NST has an effective impedance of 50K Ohms.
 >
 > Capacitor value for resonant match = .0053 uF, ie, 5.3 nF
 >
 > With stationary sparkgap, best capacitance = 1.6 * Cres = 1.6 * 5.3 nF =
 > 8.48 nF = .0085 uF
 >
 > For synchro RSG, best capacitance = 3.2 x Cres = 17 nF = .017 uF  (this is
 > absolute max value)
 > 2.8 to 3.2 is good range for synchro RSG's.
 >
 >
 > Voltage rating using MMC type caps:
 >
 > Erms = 15 kV     15 kV x 2.5 = 37.5 kV (total DC rating for each string)
 > this requires 18-19 caps per series string
 >
 > with synchro RSG and cheating a bit on the voltage rating:
 >
 > .15 uF / 17 caps per string = .0088 uF per string x 2 strings = .0176 uF =
 > 17.6 nF bank total capacitance
 >
 >
 > Your .02 uF rating would be extreme even for a synchro RSG type sparkgap
and
 > way to large for a stationary sparkgap.
 >
 >
 > Dr. Resonance
 >
 > Resonance Research Corporation
 > E11870 Shadylane Rd.
 > Baraboo   WI   53913
 >  >
 >  > My caps are Cornell 942C16P15k   rated -at-.15uf 1600VDC . I figured on a
 > total
 >  > capacitance
 >  > of around .02 uf , why am i way off here?
 >  > I have a safety gap set a hair over firing gap space about .28". What I
 >  > don't understand is if ..02uf is way overkill for a 15/30 with a static
 > gap
 >  > why does the coil operate with my 9/30,
 >  > I would like to properly match MMC size and Gap size for this 4" coil
 > based
 >  > on  some recommendations
 >  >
 >  > I have not blown any other caps since then
 >  > when I apply power to the coil  with  a 15/30
 >  > the gap fires briefly the coil functions for 1-5 seconds and then
stops.
 >  >
 >  > Steve
 >  >
 >  > Steve
 >  >
 >  >
 >  > Message -----
 >  > From: "Tesla list" <tesla-at-pupman-dot-com>
 >  > To: <tesla-at-pupman-dot-com>
 >  > Sent: Thursday, February 05, 2004 10:12 AM
 >  > Subject: Re: tesla virgin no more ! but need help
 >  >
 >  >
 >  >  > Original poster: Mark Broker <mbroker-at-thegeekgroup-dot-org>
 >  >  >
 >  >  > Congrats on first light!
 >  >  >
 >  >  > .025uF is *way* too much cap for a 15/30!  You want more like .008uF
 > for a
 >  >  > static gap and a 15/30.  Did you retun when you removed capacitors?
 > Are
 >  >  > you using a Safety Spark Gap?  Did you set it properly before
 >  >  > operation?  What type of MMC cap are you using?  Brand and model
will
 > be
 >  >  > great, or just type of dielectric will suffice.  Where on the caps
are
 > the
 >  >  > holes/failures located?
 >  >  >
 >  >  > My first MMC used 11 caps per string of 1600VDC caps.  No problems
 > there
 >  >  > despite shorting the MOVs in a "Terry Filter...."
 >  >  >
 >  >  > So I, too, think that your MMC is probably suspect.  Answers to
these
 >  >  > questions will help us determine what's going on.
 >  >  >
 >  >  > Cheers,
 >  >  >
 >  >  > Mark Broker
 >  >  > Chief Engineer, The Geek Group
 >  >  >
 >  >  >
 >  >  > On Wed, 04 Feb 2004 18:07:59 -0700, Tesla list <tesla-at-pupman-dot-com>
 > wrote:
 >  >  >
 >  >  > >Original poster: "steven hyman" <steve502-at-bellsouth-dot-net> I have
been
 >  >  > >building my first coil (Researched this lists archives for over a
 > month
 >  >  > >,along with all the websites Thanks), and had first sparks
 >  >  > >on Saturday  WOW!!!, about  15 inches, but having some problems, I
 > cannot
 >  >  > >figure out, and need some expert advise
 >  >  > >
 >  >  > >     Spark gap , static type with 6 ,1" diameter x2" long copper
pipes
 >  >  > > laid out flat, gap spacing about 1mm  with fan
 >  >  > >.  MMC with 2 strings 12 each string(24total of 1600kv .15uf
 > poly's.Total
 >  >  > >value .025 uf ??? ( can someone check this)
 >  >  > >      I am presently powering this coil with 15/30 NST
 >  >  > >
 >  >  > >first light was great, ran the coil 10-15 short runs 12-24 inch
 >  >  > >sparks.   Then the  spark gap would only fire for about a second
and
 >  > stop,
 >  >  > >after inspecting the MMC realized I had burned 2 caps up ( big
holes
 > in
 >  >  > >two caps together in series), I replaced these caps, and added 3
more
 > per
 >  >  > >string( now qty 15- .15uf 1600kv each per string x 2 strings)) but
 > same
 >  >  > >problem, after some evals, my present  situation remains the same ,
if
 > I
 >  >  > >remove the parallel connection between the 2 strings of 15 caps,
and
 > use
 >  >  > >each string alone, the gap fires ( but no sparks from top load( I
can
 > get
 >  >  > >spark from topload with breakout), but if I reconnect the 2 strings
of
 >  >  > >caps , same problem, gap only fires for about a second or two, and
 >  >  > >nothing, I have tried the coil using a smaller NST (9/30 )   and
the
 > coil
 >  >  > >works well all components working with about 15" sparks.
 >  >  > >
 >  >  > >4" secondary 1050 turns ,24awg, 21.5 " coil length
 >  >  > >12 turn primary 1/4 od, 1/4 spacing( tuned at about 7 turns)
 >  >  > >
 >  >  > >I suspect the MMC  configuration, but cannot figure this out !! I
 > thought
 >  >  > >15 x1600kv caps would suffice for a 15/30 nst (15 x 1600=24kv
 >  >  > >any help would be greatly appreciated
 >  >  > >
 >  >  > >Steve
 >  >  > >
 >  >  > >
 >  >  >
 >  >  >
 >  >  >
 >  >  >
 >  >  >
 >  >
 >  >
 >  >
 >
 >