Re: 833 coil & Newark filament transformers

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

Original poster: "Scott Hanson" <huil888-at-surfside-dot-net> 

Actually, Newark lists two filament transformers that might be suitable for
use with 833A triodes, assuming that they are still available. Although
their on-line catalog shows no filament transformers at all, a 2001
hard-copy catalog (#118) shows two transformers by Hammond that are of
interest.

Catalog #66F7434 (Hammond #167S10) provides 10V -at- 10A, with a center-tapped
secondary and a 115V primary,  but only hi-pot tested to 2kV. Actual
"operating" insulation voltage rating is not given, but is likely to be
considerably less than the hi-pot test value. Cost was $38.66 in 2001.

Catalog #83F8594 (Hammond #185F10) is a dual primary, dual-secondary
transformer hi-potted to 4kV. Primary is 115/230V, and the center-tapped
secondary is rated for either 10V -at- 13A or 5V -at- 26A. This transformer would
give more give the option of using either 115V or 230V input, as some of the
large commercial plate transformers have only a 230V primary. Also, this
transformer could be used with an 805, a 304TL/TH, or many of the older
triodes with 5V filaments. Cost was $38.13 in 2001.

Regards,
Scott Hanson





  ----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, September 27, 2003 8:10 AM
Subject: 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
 >  >
 >  >
 >  >
 >  >
 >  >
 >
 >
 > ---
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 >
 >