Re: [TCML] can you connect the secondary *directly* to the primary?

["Tim Meehan" <btmeehan@xxxxxxxxx>]

Lots of great info there, thanks very much - the cap is actually 10nF 20kV
(2 20nF 10kV caps in series).  I would imagine that a 1uF HV capacitor would
be as big as a trash can.

I had ordered some 28AWG magnet wire for the coil, I lost count after about
1500 turns.  From what I have been reading, the small diameter coils aren't
in much favor - and I should probably get it to around 3" or 4".  The other
thing that I have been hearing a lot of here, and in books and websites is
that people are quoting lengths of wire - I think I remember Tesla writing
that you want to have a length of wire about 1/4 the free space wavelength
of your intended resonance (I'm quoting from my memories of the biography,
and I'm probably misquoting).

I know that NST's are easy to find, MOT transformers are probably just as
easy, but are there other sources of transformers that would be better
suited for larger coils that didn't involve finding a scrap X-ray machine or
something?

The other thing I have been concerned about was about bad things I might be
doing to the power in my house (me blowing up the TV in my house would not
make me a popular person).  Do any of you adjust the power factor of your
mains-side transformer circuit?
On Nov 15, 2007 11:56 PM, Scott Bogard <teslas-intern@xxxxxxxxxxx> wrote:

>
> Tim,
>
>     After looking over your design, and given the specs you gave us,
> there are a few problems, but I think you can fix them.  Firstly, ditch
> the chokes, as you said they will kill your NST.  To properly filter
> your NST you should use a Terry filter.  Back when I used to run OBITs,
> I did not use a filter at all, and they lasted a long time (they still
> run), just do not open your spark gap any wider than it can start an
> arc without the rest of the Tesla circuit cap installed, this will
> ensure your tank voltage is clamped at the NSTs rated voltage.  Your
> secondary proportions area little off, What kind of wire are you using?
> how many Turns?.  If I was you, I'd go for broke (go to the hardware
> store) and get a 3-in PVC pipe, and wind it with 28AWG wire, about
> 17.5-in.  That would make for a well balanced, and more powerful
> secondary.  Your spark gap needs some work, but the good news is, not
> as much as you may think.  My first spark gap was two bolts, mount them
> in "L" brackets, screwed down to something plastic, like a cutting
> board (broad side facing each other, and try to use brass, and not
> steel, which is lossy and gets real hot).  Don't use wood, it incurs
> losses (although some people get away with it, I always had problems,
> especially on humid days).  There are lots of easy spark gap designs
> out there, just peruse the archives and some coiler webpages.  Are you
> sure your capacitor is 1 uf and not 1 nf?  1 uf is a huge capacitor, 1
> nf is probably a little small, but your secondary is small so it may be
> good.  If worse comes to worse, use glass bottle caps (lossy yes, but a
> great learning tool, infinitely adjustable, practical on small coils
> where not a lot of caps are needed, as cheap as capacitors come, 35.7
> seconds to make one, and the corona around the edges looks really
> cool!).  This will also ensure you return the cap in working order.
> Find yourself a topload, you didn't mention it, unless I missed it.
> And most importantly, disconnect your secondary from your primary, and
> hook it to some large grounded metal object (like a ground rod, or even
> a metal support beam, cold water pipe (if you know it is copper to the
> source, this implies you installed it yourself)).  Since it is an NST,
> the primary tank circuit should not be grounded as it is a center
> tapped transformer (most likely), but you should ground your NST case
> to the ground (I used mains with my OBIT coil, but I think you are
> supposed to use the RF ground to be proper).  It sound like you have a
> lot of measuring tools at you disposal, that is good, it puts you at an
> advantage for starting out.  Also if you do design a new secondary,
> make use of Java TC, it will do a lot of number  crunching for you,
> once you get acclimated to using it, or have somebody show you how it's
> done.  Best of luck!  Let us know how it goes.
>
>
>
> Scott Bogard.
>
>
>
>
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