Re: Improving my poorly designed coil

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

Original poster: Gregory Hunter <ghunter31014-at-yahoo-dot-com> 

I have 3 suggestions:

* get a better spark gap, I recommend a single static
sucker gap

* get a bigger tank cap. 50nF should be about right

* get a real topload. 4" aluminum dryer duct wrapped
around two 9" pie plates should improve performance
considerably

By following my own advice, I've extracted up to 45"
sparks from a 4" x 18" secondary, and up to 60" from
my 4" x 24" secondary using a pair of MOTs and a
voltage doubler for power.

Cheers,

--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "Chris the great"
 > <downnessisgoingup-at-hotmail-dot-com>
 >
 > Well, I got my first coil running.  It is ill
 > designed, has a horrible
 > primary and topload, but has hooked me onto coiling
 > for life.
 > Of course, it is only running on 2 MOTs, which is
 > very dissapointing (I'll
 > get more soon!) running through the simple voltage
 > doubler they use in the
 > microwaves, giving me 60 12000 volts pulses every
 > second.  This is giving
 > me a max spark of 8 inches :(.  Also, I am getting
 > corona forming from the
 > center of my secondary to the strike rail.
 > So, I need suggestions for improving my piece of
 > junk.
 >
 > Power source- 2 MOT's in series, fed through voltage
 > doubler, giving 12000
 > volts 600mA pulses.  Also keeps gap from power
 > arcing.
 >
 > Capacitor- around 0.015 to 0.02uF.  I'm not sure,
 > because I don't have a
 > capacitance meter.
 >
 > Primary coil- 8.75 turns of 0.25 inch wire, tapped
 > at 7.75 turns. This is
 > my wonderful inverted conical coil, tilted at 30
 > degrees.  The inner turn
 > is 1 inch from the bottom of the secondary (radius
 > 3.25 inch) and the top
 > 4.5 inches away (6.75 inch radius).  The strike rail
 > is about 7 inches from
 > the coil and about 7.75 inches up from the bottom of
 > the secondary.  The
 > corona is appearing from about 10 inches up the
 > secondary.
 >
 > Secondary- 22 inches high, 4.5 inch diameter, 1080
 > turns of 24 gauge wire.
 > Several coats of varnish.  inductance is 19.6mH,
 > capacitance is 8.5pF.
 >
 > Top- half shere, diameter same as secondaries.  This
 > actually works well
 > since it isn't a true sphere, and merely the bottom
 > half of a plastic
 > peanut butter jar covered in foil.  capacitance=
 > 2.1pF
 >
 > Frequency is about 334kHz.
 >
 > Spark gap is two bolts spaced at near max distance,
 > inside a plastic box
 > about 5 cubic inches.  This muffles the sound a bit,
 > so you can really hear
 > how loud the streamers are.  No problems with this,
 > getting good clean
 > firing and good quenching.  Also it is set at the
 > proper distance so I'm
 > not firing at too low a voltage.
 >
 > Anyway, got any suggestions?
 >
 > _
 >
 >


=====
Gregory R. Hunter

http://hot-streamer-dot-com/greg