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And more NST stuff
Hi John, Jon, all
John wrote:
"Regarding my last e-mail...
I thought I was posting to the list !! Realized after I pressed send
that it went directly to you, I didn't realize the e-mail was from you
directly."
That mail was supposed to go to the list. I have no idea what happend.
Did the list get it? If not, I will re-send it, because it was
(partially) an answer to Jon Rosenstielīs mail from the other day.
Terry:
Do you have any idea, what went wrong? I adressed it to the list,
but received it with "(by way of Terry Fritz <twf-at-verinet-dot-com>)"
added to the "from" header.
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).
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. 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???
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)
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.
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.
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