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RE: First light with 833 tube coil, then silence



Original poster: "Cameron B. Prince" <cplists@xxxxxxxxxx>

Hi David,

I know that we are all glad you are back up and running... It's also nice to
know that you've noticed the same results that I have with the raised grid
coil. I'm wondering if anyone else has tried this and gotten better results.

I would also advise that you adjust your grid resistor starting at about
20k. Up high like that, you should notice that the sword like arcs will have
split ends of sorts. At the ends, you'll notice the single arc splits into
multiple smaller arcs. It looks almost like a firework and has a distinct
pop after the normal thud of the arc forming.

Once you see these symptoms, the best output is achieved with the resistance
adjusted down just before this phenomenon starts to happen. If you move the
grid coil after making this adjustment, you'll have to readjust to
compensate for the movement as the position of the grid coil has a great
impact on this.

I know you'll hit that 3 foot mark with a little work.

Take care,
Cameron

> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Sunday, September 24, 2006 9:33 AM
> To: tesla@xxxxxxxxxx
> Subject: Re: First light with 833 tube coil, then silence
>
> Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
>
> Hi all,
>
> Well after a telephone troubleshooting session with Cameron Prince
> tonight, we (mostly Cameron- he'd make a troubleshoot suggestion, I
> would try it out and report the outcome) finally figured out why my
> VTTC was getting no output. I had removed the lead from the staca-
> to controller to one of the filament electrode pins of the tube and was
> therefore operating without a filament ground. Once I reconnected
> that, I was back in business ;^) I had even removed the 3 nFd mica
> cap from the circuit and tried charging it directly from a HVDC source
> to see if it vould hold any spark, all of this while on the phone with
> Cameron. Of course the mica cap checked out fine in this fashion.
> I got the stacatto controller better adjusted and now it's working
> a lot better as well. I'm still only getting 10 to 12" swords with the
> stacatto controller and about 8 to 10" sword like sparks operating
> in continuous mode, both drawing between 15 and 20 amps at
> about 110 to 115 volts input. I get the best output when I tap in
> at the topmost (30th) turn of the primary, so that tells me that I'm
> not able to tune it to a low enough frequency to resonante with the
> secondary coil. The secondary coil is about 16.5" linear of #30
> triple build magnet wire on a 3" PVC form. I think Steve Ward
> (and Cameron) were using #28 with a 2 nFd (Cameron uses
> 2.4 nFd) wound on the same sized PVC pipe with about the
> same winding length. So, I'm going to either need to get a bigger tank
> cap or wind a bigger primary (I like the bigger cap idea better :^)
> to get this thing tuned in properly. You can look at Cameron's
> VTTC that he built on his website and that will give you a general
> idea of the specs of mine. I will try to post a few pics for Cameron
> to host on his Teslauniverse site after I get the "bugs" worked out
> and I'm getting those 3 footers like Cameron ;^)))
>
> David Rieben
>
>
> ----- Original Message -----
> From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Saturday, September 23, 2006 11:44 PM
> Subject: Re: First light with 833 tube coil, then silence
>
>
>  > Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
>  >
>  > Hi Cameron, John G,
>  >
>  > I checked the output of both of mt MOTs and they were both good.
>  > I even checked to make sure that the MOT filter caps were taking on
>  > a good charge after powering up by shorting a srew driver blade across
>  > their terminals immediately after shutting down the power before the
> in-
>  > ternal bleeder resistors bled down the charge, possibly suspecting the
>  > diode had failed short circuit. The caps wouldn't always be left with a
>  > full charge immediately after shutting the power down since they won't
>  > always be shut down at the sine wave peak and in my case, they would
>  > be left with a full charge every time after shut down.  Like I said
> before,
>  > the main G3 tank cap makes absolutely no spark from shorting its 2
>  > terminal ends with the power applied. I did not try this before the
>  > output went to zero, but it stands to reason that this should reveal
>  > some visible discharge if the cap is putting out oscillations into the
>  > primary coil. Also, the primary coil now stays cold when I do turn
>  > it on, whereas it would get warm after running it a few minutes
>  > when there was an output, so it seems that no oscillations are getting
>  > to the primary coil
>  >
>  > Also, I think that my primary coil was a little short with its 30 turns
>  > coupled with my 2 nFd primary capacitance since the output kept
>  > getting a little better each time the I added more turns all the way
>  > up to the 30th and final turn, when it was working. May opt for
>  > a little bit primary cap, like 3 nFd, to make my current primary coil
>  > tune in better once I figure out what's wrong. I think the #30 AWG
>  > secondary coil is making it resonante at a lower-than-expected
>  > frequency compared to the one that Cameron built using #28 AWG
>  > wire.
>  >
>  > David
>  >
>  >
>  > ----- Original Message -----
>  > From: "Cameron B. Prince" <cplists@xxxxxxxxxx>
>  > To: "'Tesla list'" <tesla@xxxxxxxxxx>
>  > Cc: "'David Rieben'" <DRIEBEN@xxxxxxxxxxxxxxx>
>  > Sent: Saturday, September 23, 2006 8:28 PM
>  > Subject: RE: First light with 833 tube coil, then silence
>  >
>  >
>  >  > Hi John,
>  >  >
>  >  > I'm am aware of and agree with your statements. However, this is a
> G3
> mica
>  >  > transmitting cap rated 12A @ 300kHz. The diode David is using is
> only
>  > rated
>  >  > at 750mA and would normally go long before the cap would. I guess
> stranger
>  >  > things have happened, but I would certainly rule out every other
>  > possibility
>  >  > before buying a new cap.
>  >  >
>  >  > This is the cap David is using:
>  >  >
>  >  > http://www.teslauniverse.com/images/vttc/DSC02483.JPG
>  >  >
>  >  > Notice it's almost as big as the tube...
>  >  >
>  >  > David is, if I'm not mistaken, running dual MOT's with the
> secondaries
> in
>  >  > series. I think it would be prudent to verify that one of those
>  > secondaries
>  >  > hasn't opened and would consider this much more likely than cap,
> diode
> or
>  >  > tube failure.
>  >  >
>  >  > David, let us know what you find.
>  >  >
>  >  > Thanks,
>  >  > Cameron
>  >  >
>  >  >
>  >  > > -----Original Message-----
>  >  > > From: Tesla list [mailto:tesla@xxxxxxxxxx]
>  >  > > Sent: Saturday, September 23, 2006 7:49 PM
>  >  > > To: tesla@xxxxxxxxxx
>  >  > > Subject: Re: First light with 833 tube coil, then silence
>  >  > >
>  >  > > Original poster: "Dr. John W. Gudenas" <comsciprof@xxxxxxxxxxxxx>
>  >  > >
>  >  > > Cameron
>  >  > > Be cautious with just voltage ratings on mica caps (or any caps
> for
>  >  > > that matter).
>  >  > > They need to handle high current too If the duty cycle is high,
> such
>  >  > > as operating in self rectification without a staccato controller.
>  >  > > The current in the tank circuit can get get up there.  With my
> dual
>  >  > > 833A VTTC which produces 24" corona without a staccato controller
>  >  > > I can run for 10 to 15 minutes before things get hot. This coil
>  >  > > destroyed at least three new 12,000 volt mica transmitting caps
>  >  > > (typical ones about 3" x 2" x 4" with the screw terminals on top).
>  >  > > One blew out the bottom and left a very unpleasant mess. I
> switched
>  >  > > to very high current composite micas in an MMC arrangement.
>  >  > > These are .0024 mfd. They are black cylinders about 3" in diameter
>  >  > > and 5" long with large brass connectors on each end with 1/4 -20
> bolts.
>  >  > > The rating was 20kv too. I tried one and had very poor spark
> output,
>  >  > > I saw this before cap failure. I put two in series then and
>  >  > > paralleled this with another string of two in series.
>  >  > > The coil worked great with no tank cap heating. The coil operates
>  >  > > around 250 kHz.  Cap problems ended completely. Good RF ceramics
> do a
>  >  > > decent job too.
>  >  > >
>  >  > > Cap dielectrics tend to get quite lossy at high currents and
> voltages
>  >  > > operating in the RF ranges.  If they can't handle the current they
>  >  > > die a rapid death.
>  >  > > I have also destroyed MMC's with my DRSSTC that I didn't
>  >  > > sufficiently  design for long duty cycles. Not from over volting,
> but
>  >  > > from too much current.
>  >  > >
>  >  > > Professors tend to get on soap boxes and preach, so today I am
> just
>  >  > > saying consider voltage and current in capacitor choice (obviously
>  >  > > dielectric too).
>  >  > > David will solve his problem as intersecting all our responses, we
>  >  > > suggested every component could be bad as well as wiring errors.
> Good
>  >  > > luck David.
>  >  > > Cheers!
>  >  > > John
>  >  > >
>  >  > >
>  >  > > On Sep 23, 2006, at 3:08 PM, Tesla list wrote:
>  >  > >
>  >  > > >Original poster: "Cameron B. Prince" <cplists@xxxxxxxxxx>
>  >  > > >
>  >  > > >Hi David,
>  >  > > >
>  >  > > >I seriously doubt that mica cap is bad... They are built to
> handle
>  >  > > >a lot
>  >  > > >more than you are throwing at them with your VTTC. When I ran it
> on
>  >  > > >mine it
>  >  > > >stayed ambient temperature.
>  >  > > >
>  >  > > >Notice that 12kV rating is not peak or maximum, it's nominal and
>  >  > > >you are
>  >  > > >only at 50% of that with the VTTC.
>  >  > > >
>  >  > > >Cameron
>  >  > > >
>  >  > >
>  >  > > Snip ---- Snip ---- Snip
>  >  >
>  >  >
>  >