Re: Your video tapes...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: FutureT@xxxxxxx 

In a message dated 1/28/07 1:14:45 AM Eastern Standard Time, 
tesla@xxxxxxxxxx writes:

> John,
>
> I was wondering how many of your coiling research
> documentation video tapes were packed full of
> information pertaining to tube coiling?  I am sure you
> could direct me to the ones which would benefit me the
> most in my vttc efforts.  I am especially interested
> in all footage where you try tubes off the beaten
> path, ones you have never tried before and then
> proceed to document the tweaks and adjustments you had
> to make to get the coil sparking again.


Brett,

One of the very early tapes shows development of the staccato
idea, which was preceded by the duty cycle control idea
which didn't work all that well.  Some of the tapes show
small tube coils which give only 12" of spark or so, and
some tapes show the 20" sparks with various tubes tried out.
Later tapes show the 3 foot sparks with and without staccato.
I experimented with various types of staccato switches such
as transistors, SCR's and thyratrons.  Other tapes show
newer portable coils giving 20" to 24" sparks using the MOT
level-shifter technique.  I tried tube magnifiers, and other
ideas.  I think I have an index for my tapes.  I'll try to find
that and send it to you.  The early staccato work goes back to
1991 or so, so it's probably mostly of interest from a historical
standpoint.  I think there are only two tapes that show much
tube interchanging work.  Many of the tapes contain both
tube coil work and spark gap coil work.  I found the
mechanical staccato experiments to be interesting because
as the rate was changed, the system sounded like a car
engine revving up sort of, and the visual effects were
interesting too.

In the cases where I tried other tubes, most of the efforts were
in physically connecting the tube and wiring it.  Generally
they worked fine with hardly any adjustment.  If it was
a triode, often no adjustment was needed.  A slight
change of the grid resistance might have been a little
helpful, but certainly the coil would produce a spark as
soon as the tube was installed regardless of the exact
adjustments.  In the case of the 813 tube, I ran it with the
grids connected together, and also with the screen driven
from a screen dropping resistor from the HVAC supply.
I think I used about 40k ohm for the dropping resistor,
and it was about 50 watt rated.  When I tied the grids
together, the tube became more of a zero-bias type tube
in a way, and I had to reduce the grid drive to 12 turns
from the normal 20 turns.  In the case of the 803 pentode,
I tied one grid to ground, and tied the other two grids
together if I remember correctly.  In later work I got
20" of spark from the 813 tube.  The 16" sparks were
from earlier tests.  The 845 triodes and EE300 tubes
were direct plug-ins.  The 810 tube again works about
the same.  For the 4-250 tetrode, I just tied the grids
together and used 12 grid turns I think.

The real challenge with the VTTC's is not in getting them
to work with a different tube, but rather to get them
running efficiently with any tube.  Once they work
efficiently with one tube, they'll tend to run efficiently
with any tube.  Here I'm assuming the tube is rated
high enough to handle the power (or can handle the
power even if it isn't rated that high, ho ho).  When you
get your tube coil running, you'll quickly see how the
coil behaves when plugging in other tubes.

John


I saw a post

> from a few years ago where you were able to plug in a
> single 813 to one of your vttc systems and manage 16
> inch sparks.  Remind me of the cost of duplication of
> your tapes and I will send you a money order (or
> PayPal) for the cost as soon as possible.  I realize
> that it could be time consuming to duplicate VHS
> tapes, so I understand whatever you see fit to charge,
> but I have always wanted to own some (or all) of your
> tapes.  Thanks.
>
> -Brett