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Re: [TCML] VTTC-tuning. John got me started ;-)

There is a VTTC on YouTube that is pretty big ( http://www.youtube.com/watch?v=7Ky4a9KPlVY ) . It uses a 3CX3000 Tube and runs at a fairly low frequency producing bushy looking sparks. It seems that most people prefer the sword like sparks these days and as I understand it, that requires the coil to resonate above 300 KHz.


----- Original Message ----- From: "Dr.Hankenstein" <dr.hankenstein@xxxxxxxxxxxxx>
To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx>
Sent: Tuesday, March 31, 2009 11:32 PM
Subject: RE: [TCML] VTTC-tuning. John got me started ;-)

Not sure.

I heard of a man in Canada about ten years ago who made a 15kw coil
called the "Coronatron"...built from a cannibalized transmitting
amplifier. Unfortunately, I don't know much else about this.

The biggest one I know of presently is Dr. Spark's "Quadzilla"; a 4 x
833C coil with an 8kw power supply. Chris brought his coil to the
Arizona Teslathon a couple of weeks ago. What I can say, is that his
coil is awesome to say the least. In staccato mode it actually sounds
like a "Huey" Helicopter!


-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of Dex Dexter
Sent: Tuesday, March 31, 2009 3:41 AM
To: Tesla Coil Mailing List
Subject: Re: [TCML] VTTC-tuning. John got me started ;-)

Hi John Freau,
What is the biggest (the most powerfull) VTTC build that you know of?
What was (is) its' input power ,spark output,and aproximate output



--- futuret@xxxxxxx wrote:

From: futuret@xxxxxxx
To: tesla@xxxxxxxxxx
Subject: Re: [TCML] VTTC-tuning. John got me started ;-)
Date: Mon, 30 Mar 2009 19:03:50 -0400


Generally speaking, if the spark length stops increasing at a
certain point as you turn up the variac, this means you need
to lower the tank frequency by increasing the tank C or
using more primary turns.  Probably best to use more primary

If you can get rid of the multiple streamers that will help
the spark length.  The multiple streamers could be the
cause of the shorter sparks, instead of what I said in the
paragraph above.  But regarding tuning, the primary tank
often has to be considerably lower in frequency than the
secondary frequency, from a calculated point of view.  This
takes care of spark loading effects, and frequency splitting
issues.  Tuning is best done at full power.  You can do this
by trial and error my moving the tap point on the primary
and turning up the power.

You can try using a taller break-out point, that might help
in getting a single streamer.  Tuning can be a factor there maybe,
and also the other fcators I mention above.

Various factors such as the degree of grid feedback, grid
resistance, tuning, main coupling, etc can affect the look
of the spark, and make them swordlike or fuzzy, etc.   It can
take awhile to really optimize a VTTC.

You can probably set the staccato board without a scope
by listening to the sound of the sparks.  When it's set up right,
the pulsing will sound "solid".

Is your main power transformer a powerful one?  That's important
also for tube coils.


-----Original Message-----
From: Christoph Bohr <cb@xxxxxxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Mon, 30 Mar 2009 3:55 pm
Subject: [TCML] VTTC-tuning. John got me started ;-)

Hello again.

As you might have followed, I was pretty happy with my VTTC's
output, until "someone" pointed out there was plenty of room for
optomization ;-) I'm just kidding...

One thing on the history of this project. During a first higher power
of the prototype I had a sparkling effekt inside the tube, presumptively
at the cathode. I nedded a second to turn the power off and since then,
the fillament is notably brigher in this spot when switching the
supply on. With soft-start this is less visible and once the fimament
is on,
I cant see any difference. However, the tube still lives, but I don't
want to
Currently there are 2 major question troubling me:

One thing I noticed is, that when I increase the pulse rate or power,
is a point at ca 70% from where on I get multiple streamers, pretty
bushy and
white hot, but the lengts does not increase from this point on.
I sould be around calculated 250KHz, which seems to be problematic from
I have read. Without toroid I could get to 330KHz... would this be
Sounds dumb, but the toriod is glued to the secondary ( OK, even dumber
I could of course detatch it, but I'd like to ask first if this makes
any sense
My idea was, that if there was a single streamer instead of multiple,
it might
longer without having to push the tube any harder.

2.: I read I needed a scope to setup staccato. I just made a PCB,
together, plugged it in, and it worked... at least I think. I have a
scope, but
what I should set up what can't be done with the controlls available on

3.: coupling. currently the bottom turn of L1 and L2 are aproximately
on the
The feeback winding starts 1cm blow the primary and extends 15 turns
until 4,5cm
below. Does this sound reasonable? I know, its impossible to give exact
I just want to see if someone says something is completely wrong....

Enough for now. For extensive tuning I should move over to my parents
I am living in an appartment which might be asking for trouble with my
or the authorities.

best regards

Christoph Bohr

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