Re: [TCML] 5.25" SRSG tesla coil suggestions on improving performance

[Scott Bogard <sdbogard@xxxxxxxxx>]

Yeah, that's what I was expecting to see from twin MOTs!  Very nice work JJ!

Scott Bogard.


On Sat, Aug 10, 2013 at 12:26 AM, JJ Dasher <redrum0381@xxxxxxxxx> wrote:

> Scott, you nailed it again!
>
> http://www.youtube.com/watch?v=AUQeDqUhI3g
>
> I used 6" aluminum ducting to toss another topload on top of my existing.
>  Another dramatic improvement!
>
> Thanks again,
> JJ
>
>
> ________________________________
>  From: Scott Bogard <sdbogard@xxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Sent: Thursday, August 8, 2013 5:51 AM
> Subject: Re: [TCML] 5.25" SRSG tesla coil suggestions on improving
> performance
>
>
> Also JJ,
>      After actually watching your video I believe your toroid is way to
> small for really long sparks.  The rule of thumb I like to use is toroid C
> in pF is roughly = to toroid overall diameter in in. (believe it or not it
> is actually really close).  Given that I found for single long sparks the
> best toroid C can be found using this formula [C=0.9* (SQRT[P in watts of
> the system]).  For a multi streamered system like you have one should
> design for 0.5(SQRT[P]) Not sure why this formula works, it just does.  So
> assuming 1 kW power you want a roughly 28 inch diameter top load, or two
> smaller top loads yielding 28 pF of capacitance for longest streamers.
> Credit where it is due I believe John Freu came up with this formula, I
> simply realized later that they matched up with my own results very well.
> Resizing your top load should help, but again I think matching your power
> draw to your system with a higher break rate will yield more dramatic
> improvement...  Remember "tuning" isn't just matching resonate frequencies,
> it is also designing your system so power draw will be optimally utilized,
> and losses minimized, this was always my biggest mistake as a beginning
> coiler, impedance matching issues...
>
> Scott Bogard.
>
>
> On Mon, Aug 5, 2013 at 9:59 PM, JJ Dasher <redrum0381@xxxxxxxxx> wrote:
>
> > Hi all,
> > I'm new here.  Although I've built a few coils in my past, I still
> > consider myself a newb coiler.  I've never been the type to do things
> > mathematically perfect, and tend to wing it as I go along, which may be
> my
> > downfall here.  For the past couple of years on and off, I've been
> working
> > on a 5.25" SRSG coil to use in a Halloween display.  This is my largest
> > coil so far.  You can see it in action here:
> >
> > http://www.youtube.com/watch?v=2P3T5zuT9DI
> >
> >
> > and pictures of the guts here:
> >
> > http://imgur.com/a/0jgxR
> >
> >
> >
> > I'd like to get some constructive criticism and advice on getting this
> > running better.  This trips my 20amp breaker after about 10-15 seconds of
> > running, so I figure about 2.2-2.6kw?  I'm currently getting 36"
> streamers,
> > which I feel are somewhat weak.  They are purple, and not very bright.
> > Specs:
> >
> > Large old powerstat variac salvaged from power equipment.  Not sure on
> > exact specs, but I assume it should handle 30+amps with ease.  Wired for
> > approx 150v boost.
> >
> > Dual MOT's (pulled from 1200w commercial MWs), currently unballasted.
> >  130uf of PFC caps behind them.
> > 180nf MMC cap built with 10 strings of 8x 942c20p15k-f's.  1m bleed
> > resistors installed.
> > SRSG is a 5" acrylic disc attached to a 1800rpm sync motor.  4 flying
> > electrodes for 120bps.  Electrodes are 1/8" thoriated tungsten.  Phase is
> > adjusted by twisting the motor in its mounts.
> > Primary is 3/8 copper tubing, slightly conical.  Currently tuned at about
> > 2.25" turns
> > Secondary is 5.25" x 24" 22awg magnet wire with a couple of coats of
> poly.
> > Topload is a spun aluminum 4.5"x18" toroid.
> > All high current busses are 4awg stranded copper with large soldered
> lugs.
> >
> > The next improvement I plan is to upgrade to 1/4" tungsten electrodes.
> >  The stationary electrodes currently glow red hot after about 5 seconds
> of
> > running, so I added a fan.
> > I'd love to get some bright long white snakes like I've seen from similar
> > size coils.  Please advise!
> >
> > Thanks!
> > JJ
> >
> > P.S.  There is normally a safety gap installed, It just wasn't in place
> > when I took those pictures.
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> >
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