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Re: 833 coil



Original poster: dhmccauley-at-spacecatlighting-dot-com 


The John Freau design i am currently using works extremely well and is well
documented on my page here:

http://www.spacecatlighting-dot-com/teslacoil12.htm

Although this design shows paralleled 833 tubes, the design would just about
identical for a single, triple, quadruple, etc... 833 VTTC.  Just need to
size your filament and plate
transformer accordingly.  10V, 10A Filament transformers are actually
readily available.  I'm not sure why everyone has a difficult time finding
them.  www.newark-dot-com sells them as
well as many other distributors.  The major filament transformer vendor now
is Hammond MFG at www.hammondmfg-dot-com  If you go to the website, just look
under distributors and place
your order.  Even if the distributor does not list a specific transformer
explicitly, doesn't mean it doesn't sell them.  I buy all my 10V, 10A
filament transformers from www.newark-dot-com and usually
get them within a day or two of placing my order.  They are about $28.00
each.

You really don't need a plate transformer.  A MOT will work great, although
for much shorter durations than a properly rated plate transformer.  Also,
you will want to build yourself a
Stacatto controller (Cathode Pulser) to reduce the average power to the
tubes, ESPECIALLY if you are only using one tube.  This way, you can still
go for the maximum arc distance, maximize
peak power to the coil, yet reduce average power.

Those small toroids from John Freau will work just fine.  You really don't
need a larger toroid as you really aren't building up total voltage on the
toroid anyways as you typically always use
a break-out point on top of the toroid anyways.  Most VTTCs i've seen use
just a small disk as the topload.

For a single 833A running with a stacatto controller, i think you could get
about 12-15" no problem.  After a lot of work and tuning, you could probably
increase length up to 20".
My maximum spark length so far with my dual 833A coil is 32" which was done
quite recentlly.  Its very sensitive to tuning and the only place i can
successfully run it at those arc lengths
is in my basement at my mom's house.  Everywhere else, performance is down
to about 24-26".

Dan



 > Hi,
 >
 > I recently acquired an 833a tube, and would like to proceed with making a
 > coil.  The only requirement that I want to impose on this project is
 > longetivity, even at the expense of spark length.  The goal is to be able
to
 > run for extended periods without worrying about tube damage, allowing for
 > various experimentation.
 >
 > Due to time constraints, I am hoping plagiarize a working, single tube
 > design.  After I have an operational coil, I can then proceed to alter
 > parameters to notice their effect.  Also, due to a relative lack of
 > knowledge with electronics, I believe that going with an existing design
 > will allow for a better learning experience than continuously fiddling
with
 > component values that I know nothing about.  Here goes:
 >
 > 1)  10v 10A filament transformers seem impossible to find.  Would I be
able
 > to use the trans out of a 12 volt battery charger and throttle it back
with
 > a variac?  Or, would it be better to use a MOT with the secondary removed
 > and wind a few turns of wire on it like everyone else has done?
 >
 > 2)  Plate transformers designed to feed an 833 are super expensive and
 > heavy.  MOTs again?
 >
 > 3)  Does anyone have a link with a solid, simple one tube design that they
 > would be willing to share?  It's my understanding that a lot of the
 > component values aren't critical, but since I'm the type of person who has
 > to be hands on to learn, they would assist me in getting together a
project
 > where results can be seen.
 >
 > 4)  I have gone thru the archives and done lots of reading on other's
 > projects to alleviate you guys from reiterating what has been said many
 > times, as well as making countless visits to Steve W's, John F's, and
others
 > websites.  I've read the tube section of my old AARL Handbooks many times
as
 > well, and am getting an understanding on the tube process.  However,
 > assembling a project that I know will perform seems to help ease the
mental
 > anguish and promote an understanding of what I am doing.
 >
 > 5)  I've got two of John F's small toroids (2 by 6?).  Will I need
something
 > bigger?
 >
 > 6)  I have to ask:  How much spark can I expect with a durable design?
 >
 > Thanks for any info,
 >
 > John Richardson
 >
 >
 >
 >
 >