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Re: [TCML] Advice for my first SGTC



Atomic,
     It definitely is better to NOT use a doubler, as a doubler WAY adds to
the complexity, and watt for watt, does absolutely positively nothing to
improve performance.  See my twin mot coil here,
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CEoQtwIwAw&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D_301ZMR6H48&ei=Q7-rUMqrKbS30QH414CgBg&usg=AFQjCNGzU3MfFG3n571uF4eVZZ0qUmCbDA
Let me know if the link works, I can't access youtube at work but I can
resend it properly when I get home.  That coil has made arcs up to 69
inches (consistently hitting 63 in) using two MOTs, no doubler, no ballast,
minimal weight, minimal complexity.  The advantage of a doubler is that
most spark gaps work better at higher voltages, as you can use more breaks,
and they are more forgiving about spacing, but your time would be better
spent building a solid rotary gap than a doubler.  A good rotary will help
you out doubler or not.  The other advantage of a doubler is you can use a
cap with a lower capacitance, BUT since MMCs are so easy, just design
one with a lower voltage and slightly higher capacitance to match it, fewer
parts already.  Also consider some of the DRSSTC's run off of as little as
400V, and get 12+ feet sparks, so no, a higher voltage in no way equates to
better performance, just a different design.  As for bottle caps, yes they
will work fine, BUT if you do go the dual MOT route, you will need a LOT of
bottles, probably close to two hundred to take advantage of all the current
(much more if you want to use a low break rate, which I usually don't, but
that is just me.) if you do use the bottle caps a doubler might be worth
the time, as it will cut your required bottle number in half, since most
bottles can handle about 15kV to begin with (but the cost to build a
doubler will probably be equal to that of a decent MMC, and you won't need
to make all those bottles.)  I hope this was helpful, Best of luck and be
safe!

Scott D Bogard.

On Tue, Nov 20, 2012 at 7:05 AM, Atomic <atomicrox@xxxxxxxxx> wrote:

> Hi Mark,
>
> Thanks and congratualations on your great coil!
> I haven't seem many dual MOTs without some sort of multiplier circuit but
> if they do work as well as yours then I might dump the multiplier. What
> kind of filter do you use?
>
> I've bought a cheap LC meter from Ebay to help me measure the bottle caps.
> Is there any specific kind of bottle I should avoid?
>
> I might consider switching to 942C's later but I'd really like to make sure
> it works and won't blow 200 bucks worth of caps.
> Also still interested in knowing if those Russian caps will work - if they
> do I'll certainly go for them. I've never heard of
> Polyethyleneterephthalate foil caps before.
>
> Cheers
>
> On Tue, Nov 20, 2012 at 6:39 AM, Mark X2 <susax2@xxxxxxxxx> wrote:
>
> > Atomic,
> > welcome to the list.
> >
> > a dual MOT supply will do fine, even without a doubler.
> > Mind the doubler part is sensitive to failure, I've blown a lot of
> diodes.
> > Maybe others had more succes with doublers.
> >
> > Bottle caps are excellent caps to begin with, despite obvious drawbacks,
> > like weight
> > I started with 72 bottles and doubled it to 144 before getting 942C
> caps.#
> > Here's a video with my old 144 bottle cap
> > https://www.youtube.com/watch?v=OGn2jlEV76M
> > It took a lot of work to construct the bottle cap, if I had worked those
> > hours and got payed, I could have also bought the 942C caps in the first
> > place.
> >
> > I don't know about those caps you found on ebay, but for the money it's
> > worth a try for sure.
> > Caps sold by the kilogram lol.
> >
> > Mark
> >
> >
> >
> > 2012/11/20 Atomic <atomicrox@xxxxxxxxx>
> >
> > > Hi guys,
> > >
> > > I'm new to this list, decided to join to get some advice before
> building
> > my
> > > first SGTC. It will use a voltage doubled dual-MOT supply similar to
> this
> > > one <http://www.capturedlightning.org/hot-streamer/greg/Mark_III.htm>.
> I
> > > know NSTs are safer but they're rare around here and I'd really like to
> > > achieve 1m arcs :)
> > >
> > > First thing I need to figure out are the caps, since they're the most
> > > expensive component...
> > > I don't have much of a budget, which is why I'm inclined to use salt
> > water
> > > caps. I've already got 30 of
> > > these<http://www.costibebidas.com.br/fotografias/grande/2418.jpg>600mL
> > > beer bottles and I can get more of them for free. Do you guys think
> > > these bottles will work fine?
> > > Another option would be making an MMC out of
> > > these<
> > >
> >
> http://www.ebay.co.uk/itm/6800pF-4000F-4KV-PETP-HV-Capacitors-Lot-90-/200838582258?pt=LH_DefaultDomain_0&hash=item2ec2e98ff2
> > > >.
> > > They are pretty cheap and 2 packs of 90 should give me
> 76.5nF@xxxxxxxxxx
> > > they work?
> > >
> > > Sorry for the long post.. hope some day I'll be able to contribute back
> > to
> > > the list!
> > >
> > > Thanks,
> > >
> > > Atomic
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