Re: Building A VTTC

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Henry Hurrass" <Dr.Hankenstein@xxxxxxxxxxxxx>

I think the whole idea of the staccato controller in the first place is to
limit the "watts dissipation" that the plate really thinks it's seeing. As
an example, if you limit the duty cycle to say 50%, you could conceivably
double the plate dissipation (thus producing a longer spark), but the
"average plate dissipation" would still be below the "max plate
dissipation" allowed for the tube. I.E.: 500W times 50% duty cycle equals
250W avg. = longer spark. Without the staccato controller (which is really
only a pulse width or duty cycle controller AKA: CW Mode) the plate would
normally melt. I personally do not like to see plates glowing any color
other than black for longevity of the tube. Who cares what the BBS rate is
as long as you find the sweet spot where you would back-off the duty cycle
to make your coil a long time AND a long spark performer. Look at the
plate: If it's glowing, you are probably giving too much "hammer".  enjoy
and BTW nice work!

regards,
Dr. Hankenstein


> [Original Message]
> From: Tesla list <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Date: 8/22/2006 11:39:31 AM
> Subject: Re: Building A VTTC
>
> Original poster: "Steve Ward" <steve.ward@xxxxxxxxx>
>
> Since the pulse rate is always some even division of 60, its pretty
> easy to listen to hear the 30, 20, 15, and 10pps.  Below that you may
> need a counter.  Most people have scopes or maybe a meter that can
> count, i dont think i would bother putting a counter circuit into the
> staccato controller.
>
> Steve
>
> On 8/21/06, Tesla list <tesla@xxxxxxxxxx> wrote:
> >Original poster: "Cameron B. Prince" <cplists@xxxxxxxxxx>
> >
> >
> >Hey guys,
> >
> >I think the consensus is we need some sort of counter to help determine
the
> >current pulse rate of the staccato controller. John, this is what I had
> >emailed you about a few weeks ago. I think it would be really nice to
> >incorporate two 7 segment displays into the controller that display
current
> >pulses per second. I have briefly looked into this and found the
schematic
> >here:
> >
> >http://martybugs.net/electronics/speedo.cgi
> >
> >It's for a digital speedometer display but I think the concept is about
the
> >same:
> >
> >1) Take a sample
> >2) Perform an average
> >3) Display value
> >4) Return to step 1
> >
> >What are your thoughts on this circuit and adapting it to interface with
the
> >staccato controller? Is there a less complex way or circuit that would
> >provide the same results that you know of?
> >
> >Thanks,
> >Cameron
> >
> >  > -----Original Message-----
> >  > From: Tesla list [mailto:tesla@xxxxxxxxxx]
> >  > Sent: Monday, August 21, 2006 6:58 PM
> >  > To: tesla@xxxxxxxxxx
> >  > Subject: Re: Building A VTTC
> >  >
> >  > Original poster: FutureT@xxxxxxx
> >  >
> >  > In a message dated 8/21/06 4:07:27 PM Eastern Daylight Time,
> >  > tesla@xxxxxxxxxx writes:
> >  >
> >  > >It seems that you have made a quantum leap in
> >  > >the stacatto controlled VTTC that probably hasn't been pa-
> >  > >ralleled since the 1990s when John Freau himself first intro-
> >  > >duced the stacatto controlled VTTC, capitalizing upon the
> >  > >higher output from the same power input through the
> >  > >priciple of lower duty cycle firing. And I also think that it
> >  > >should be pointed out to the rest of the list that this is your
> >  > >very first VTTC project, so basically you've made these
> >  > >advances as a VTTC beginner!
> >  > >
> >  > >Keep up the good work,
> >  > >David
> >  >
> >  >
> >  > Cameron, David,
> >  >
> >  > Yes, Cameron has obtained very impressive results from his
> >  > VTTC project.
> >  >
> >  > My original coil that gave the 36" sparks, and later
> >  > the one that gave 38" sparks didn't have a staccato system
> >  > attached, so they ran at 60 PPS, and drew a lot of power.
> >  > These early designs were unable to give the straight sword-like
> >  > sparks, so the sparks tended to get a lot shorter when the
> >  > staccato feature was added.  I did at some point add the
> >  > staccato feature but the sparks got shorter when the staccato
> >  > was operating.
> >  >
> >  > One of my early coils gave the sword-like sparks.  In this
> >  > coil the spark length did not decrease in the staccato mode.
> >  > I could reduce the pulse rate to 1 pulse per minute, and the
> >  > sparks remained just as long.  But this was a smaller coil
> >  > which produced 20" sparks from a single 4-250A tube
> >  >
> >  > When I added the staccato system to my coils in general
> >  > I didn't go back to modify the coils to take advantage of the
> >  > staccato features, so the sparks didn't get any longer, the
> >  > input power simply decreased.
> >  >
> >  > When I had spoken to
> >  > Steve Ward and others, I suggested that they modify their coils
> >  > (compared to mine) by lowering the plate impedance to take
> >  > advantage of the staccato capabilities.  This is what I was planning
> >  > to do but I got involved in other work.  Also around that time I had
> >  > introduced the zero-crossing staccato circuit which helped a lot for
> >  > staccato stability.  I sent this schematic to Steve Ward and he
> >  > incorporated it into his coil and placed the schematic at his
> >  > website.  He did optimize his coils to take advantage of the
> >  > staccato, by lowering the plate impedance.  Cameron has
> >  > done that also.
> >  >
> >  > Some later coils that I built did give the sword-like
> >  > sparks, so they were able to maintain their spark lengths
> >  > while running at a slower staccato pulse rate.  One later design
> >  > coil (circa Feb, 2001) produced 24" swordlike sparks in the
> >  > staccato mode and also without staccato.  This coil used two
> >  > 833A tubes and was capable of running without staccato
> >  > without overheating the tubes.  It produced 24" sparks.
> >  > When running without staccato it drew 2400 watts while
> >  > producing the 24" sparks.  By using the staccato, the
> >  > power draw could be dramatically reduced depending
> >  > on the pulse rate.  For example if the coil was run at 30 PPS,
> >  > Then it drew 1200 watts (somewhere around 10amps).  If the
> >  > coil was run at 15 PPS, then it drew 600 watts (~ 5 amps).
> >  >
> >  > I use a similar formula to my formula for spark gap coils,
> >  > for VTTC's without staccato.
> >  >
> >  >       spark length inches = 0.5*sqrt input watts.
> >  >
> >  > This formula is for VTTC's which are running at the full 60 PPS
> >  > (no staccato).  The coils will of course be much more "efficient"
> >  > in staccato mode.
> >  >
> >  > As an example there is my 2nd large VTTC coil which gave the
> >  > 36" sparks at around 5500 watts.  So if we take the sqrt of
> >  > 5500 = 74.16.  Then multiplying this by 0.5 gives 37" which is
> >  > very close to the 36" I obtained.  I think I turned up the power
> >  > a little higher to get the 38" which I eventually obtained.
> >  >
> >  > Now we can do an example with staccato mode.  Consider
> >  > my coil that gave 24" sparks both in or out of staccato mode.
> >  >
> >  > without staccato:
> >  >
> >  >     24.49" spark length = 0.5*sqrt 2400 watts
> >  >
> >  > So it can be seen the formula is quite accurate for this coil also.
> >  >
> >  >    But with staccato at 20 PPS the formula must be modified.
> >  >
> >  >    24" spark length = 0.76*sqrt 1000 watts
> >  >
> >  > note I used 1000 watts instead of 800 watts to allow for the
> >  > filament power for the two tubes.  In some of the calcs here
> >  > I didn't bother accounting for filament power.
> >  >
> >  >    At 15 PPS:
> >  >
> >  >    24" spark length = 0.86*sqrt 800 watts
> >  >
> >  > I think at some particular slow pulse rate
> >  > the spark length diminished some.  I'm not sure though.
> >  > If the staccato pulse rate
> >  > is very slow, the spark will not appear continuous but will
> >  > appear pulsed when viewed by eye.  When speaking about
> >  > the efficiency of a staccato tube coil, it's best to give the
> >  > staccato pulse rate because the pulse rate has such a
> >  > dramatic effect on the power draw.  When the coil runs
> >  > at 30 PPS, the sparks look almost as full as at 60 PPS.
> >  > At 20 PPS the sparks look good too.  Each pulse rate
> >  > has it's own interesting appearance and sound.  When
> >  > the rate gets slow enough, down to 15 PPS or so, only
> >  > a single sword like spark will be seen.  This sword spark
> >  > will waver back and forth slightly as the coil runs.  This
> >  > type of spark can be seen at my website, as well as
> >  > other types of sparks.
> >  >
> >  > Basically if you optimize the VTTC for staccato, then it will
> >  > not be able to run continuously without staccato.  The tubes
> >  > will overheat.  So there's a tradeoff.  Either use a high plate
> >  > impedance and permit the coil to run at the full 60 PPS
> >  > (no staccato), and limit the spark length (even with staccato
> >  > turned on).   Or use a lower plate impedance and only
> >  > run in the staccato mode at 30 PPS or less to prevent the
> >  > tube from burning up.  But longer sparks will be obtained.
> >  > The coil can be turned up to full power without staccato
> >  > for short durations, but not continuously.  Keep an eye
> >  > on the tube plate and watch for excessive redness.  Turn
> >  > down the power very quickly as needed.
> >  >
> >  > John
> >  >
> >
> >
>
>