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Re: And more NST stuff
In a message dated 99-04-12 05:53:42 EDT, you write:
<< John wrote:
>> "You can just wave a neon bulb or fluorescent tube back and forth
>> quickly close to the coil. It will show dots of light as the coil
>> fires. From the grouping of the dots, you can tell the break rate
>> of a static gap. Richard Hull shows this on one of his excellent
>> Video Report tapes."
> Hmm, interesting idea! Would the speed, with which you wave
> the FL-tube with make a difference? (When comparing from
> one coil / gap / cap setup to another).
Reinhard,
You just have to be sure to wave it fast enough to see all the
breaks within a couple of half-cycles, so you can see the pattern.
> To make things more complicated, my next question: Assuming
> I would build a sync RSG, but not for 120 (100) bps, but for, say
> 240 (200) or even 480 (400) bps. The gap firing is still in sync
> with the mains in this case. However, I am not firing 2 per cycle
> but 4 or 8 times. As the gap is "in sync" with the mains, I canīt
> see that overvolting a component would be possible. I have
> seen a few coilers (I believe Bert Hickman was one) that claim
> a static gap can fire many times (the mains frequency) per
> cycle.
Yes, that's a fact that the static gap can fire many times per cycle.
> My own gut feeling tells me my static gap DOES indeed
> fire at a higher rate than 100bps. My static gap uses 10 gaps,
> each set at roughly 1.6mm for 16mm (0.63") total. My safety
> gap (total width) is only marginally larger (around 0.7"). I know,
> Iīm pushing it... (:o)). (Which only lets my trust in the MMC
> grow!!) The coil starts firing at about 70% of the variac setting
> (which means roughly 235V nominal) Once the coil is running, I
> can reduce the variac setting to about 45-50% before the gap
> starts firing erraticly. The length of the streamers doesnīt
> change much (their appearance and speed does, tho). At
> 270V (the max my variac puts out) the core does NOT
> saturate. Well, anyway, I am asking about the "higher than
> 2xFmains sync rotary", because for a 4500 to 5500W input,
> my needed mains resocap becomes gigantic. For 4.5 kVA
> I would need a 254nF (oops) cap using the formula. If the
> best cap should be larger (as has been suggested), then it
> only gets worse. So, it would be nice if I could "cheat"
> using a sync gap (to save my neons) at a "higher than
> usual, but still in sync" bps rate. I understand the problems
> involved using "pace maker supported" xformers
> (i.e: neons) with a non sync rotary, but using a high break
> rate sync gap would be nice to keep the cap size down.
> Is this possible / practical / safe???
I've never tried the higher than 2F mains break rate with an NST.
As you said, the cap would have to be small enough so the gap
fires at every presentation. But it seems to me that it would work
fine. The adjustment would probably be critical as Richie has
suggested.
> RWB:
> >So, what we need, is an equation that will let us
> >determine (for RSG users) the best cap size for
> >a given breakrate.
> JF:
> >This will will be needed only for NST or other
> >current limited xfrmers of course.
> Okay, but arenīt all xformers, which are used in
> TC work, current limited in one way or the other?
> (pigs = externally limited)
Yes, but with external current limiting, you can adjust the amount
of limiting to match the cap size. Actually you did this with your
German type NST, I think you mentioned also.
> JF:
> >I think that as the cap gets bigger, it won't charge as fully,
> >so any advantage will be lost after some point.
> I have always thought the mains resocap is THE biggest cap
> a certain transformer can fully charge. However, your and
> Terryīs experiments seem to prove quite differently.
Yes, but in my tests, I could only successfully charge a larger
than mains resonant sized cap, by using more than the rated
input voltage to the NST. Or at least that's how it seems so far.
> Might the difference in xformer construction be the reason
> why Jon Rosenstiel and I are getting different resocap
> results? I mean the different reactions of our transformers
> to shunt removal and / or adjustment.
I seem to have lost the thread. What was the difference in
behaviour between your's and Jon's systems again in a nutshell?
John Freau
> J.R.īs U.S. NST: (the way I remember U.S. NSTs)
---------------------------------------------------------------
> 1.) One primary coil in the center
> 2.) Two secondaries (centertapped to core)
> 3.) Design: C-S-C-P-C-S-C
>(C: core S: secondary winding P: primary winding)
> 4.) Shunts on either side of the primary
> My NST:
------------
> 1.) Two primaries (bottom of double "I" core)
> 2.) Two secondaries (centertapped to core)
> 3.) Design:
>CCCCC
> S S C: core
> C ss C S: secondary winding
> C ss C P: primary winding
> P P s: shunts
> CCCCC
> 4.) Shunts in the center of the core.
> Please see my other mail for a better scheme of my NST.
> Coiler greets from germany,
> Reinhard
>>