[Prev][Next][Index][Thread]
Re: Ok, so maybe we will have plenty o' NSTs : )
Hi Nathan, all,
Sorry about the briefness of the mail (time.... :o( )
> Original Poster: "Nathan Ball" <nateburg-at-hotmail-dot-com>
> What I heard is that it's a simple GFP (Ground Factor Protection or
> something) Circuit breaker that is thrown when the transformer is
>shorted.
The real problem is the fact (in Germany) that they are starting
to use electronic (i.e.: HF/HV switchers) transformers. You
would need to disable the fail safe on the PCB, which means
reverse engineering the circuit diagram. Even then, I doubt these
xformers would be able to withstand the harsh enviroment that
a TC circuit presents.
> really nice to be able to control the speed of my motor.
>I understand It is very easy to burn out NSTs with a
>rotary gap.
If you plan on running a RSG, ONLY do so (on neons) with
a sync RSG. NSTs are NOT designed to run at HV. Their
insulation is not designed for this. In sign service, they only
briefly see HV to ionize the gas inside. Once the tube starts
to conduct, the tube´s postive V/A curve presents a sort of
short to the NST, which is why they are current limited, and
the output voltage drops (depending on tube length, # and
diameter) to 450-1000V maximum.
> I know if you run a static gap at the widest setting it makes
> your transformer run at it's highest voltage. Would I be right
>thinking if you make your BPS too fast it does the same to
>the transformer?
No not really. A static gap is free firing. I.e., when the voltage
is high enough to cross the space, it will fire. This depends on
quite a few factors. The RSG, on the other hand, is a "force
triggered" device. It can ONLY fire, once the electrodes align.
If your setup is done incorrectly, you will experience a very
high voltage rise (before the electrodes align) and this can and
will kill your NST and caps.
> One last thing: I was looking around for plastic for dielectrics, and
>saw inBrent Turner's Tesla Coil Book that Polyethylene
>Teraphthalate has a fantastic voltage rating (About 4000 V/mil)
>and also a dielectric constant of about 3. I called around to a
>bunch of plastics companies, and nobody recognized that name.
Strange, PET is probably one of the most common plastics
around. Maybe they don´t know it by the chemical name.
> two liter bottles and such. Is this right? has anybody out there
>tried using two liter bottle plastic in their caps? It averages about
>13 mil on the micrometer... so that's about 52,000V if the listing
>for the dielectric strength in The Tesla Coil Book is accurate.
>That would mean 0.026 mil and a 100,000V dielectric strength!
>Is this too good to be true?
Unfortunately, yes because of three reasons:
a.) PET is terribly lossy at RF frequencies (gets hot and melts).
b.) Your average bottle is only partly "virgin" PET. The rest is
recycled trash from old bottles.
c.) You´ve got a mike. Cut apart a PET bottle and take several
measurements. You would be surprised as to how much the
thickness can vary (very similar to nay kind of plastic sheeting,
including the old beloved PE).
My advice: Go for an MMC. I have written quite a bit about this
subject. You will find it in the archives starting somewhere in
October of 1998. Terry Fritz also refined the whole thing and
designed the EMMC, which compromises lifetime for cost
(although still very effective). If you have ever doused in motor
oil ,etc, you will love the advantages of the MMC over ANY other
type of homebrew cap.
Coiler greets from Germany,
Reinhard
Happy New Year to all. Hope you get into the new
millenium safely. I hope the Pupman List is Y2K
compatible ;ö))