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Re: Help in calculations (fwd)
---------- Forwarded message ----------
Date: Tue, 30 Apr 96 13:47:00 PDT
From: Richard Hull <RICHARDH-at-whitlock-dot-com>
To: bin <bin-at-poodle.pupman-dot-com>
Subject: Re: Help in calculations
Richard Quick and all others,
I absolutely agree wholeheartedly with Richard's statements!!!! The
synchronous rotary gap is nice, but nothing beats the total control of a
variable speed rotary. This is provided it is backed up with
inductive/resistive ballast control at the primary side. The art is at the
hand of an experienced user in the manner in which the speed and ballast are
handled and adjusted during actual operation to arrive at a truly optimum
condition of operation. Tune for minimal smoke and hottest arcs!
Richad Hull, TCBOR
----------
From: bin
To: Tesla-list-subscribers
Subject: Re: Help in calculations
Date: Friday, April 26, 1996 9:43PM
>From richard.quick-at-slug-dot-orgFri Apr 26 21:18:19 1996
Date: Fri, 26 Apr 1996 04:50:00 GMT
From: Richard Quick <richard.quick-at-slug-dot-org>
To: tesla-at-pupman-dot-com
Subject: Re: Help in calculations
Talking about neons and synchronous gaps I said:
> I tend to side with the theory that letting the tank circuit
> capacitor decide when Vmax occurs is best. When the voltage
> peaks (meaning the cap is fully charged and the line voltage
> rises due to the reduction in current flow into the capaci-
> tor), the static gap should fire if it is properly adjusted.
> The peak power should be delivered if the gap is rapidly
> quenched after firing.
Quoting Charles Brush
> What are your thoughts on this subject with regard to pole pig
> powered systems? Not having gotten into this myself yet, I've
> been wondering if you'd ever run into problems with an
> asynchronous rotary gap going in and out of phase with the
> charge time of the caps. I.E. the caps occasionally reaching
> Vmax when the rotary's gaps are not aligned for firing. Have
> you or others here ever heard any "beating" in your rotaries or
> noted any in the coil's output? I realize that rotaries
> are the norm on larger systems due to quenching problems with
> static gaps, but if some sort of "super" quenching static gap
> was possible would this be ideal? (in terms of always allowing
> Vmax...I realize that this is theoretical and might not be
> practically possible)
I have experimented with a synchronous gap on a pole pig and I
was not really super impressed. The name of the game here is RF
power processing, meaning you want high throughput in the system.
Long sparks are as much a factor of the raw power as they are of
Vmax on the capacitor when the gap fires. Variable asynchronous
gaps will deliver high throughputs, but the ideal Vmax spark
excitation of the tank circuit is not an infrequent occurance.
With the pole pig and adjustable current limiting you can flood
the synchronous gap to overloading with ease. Kickbacks, tank
circuit instablity, and excessive capacitor stress (as seen in RF
leakage, failed bypass capacitors, and heavy activity in the
safety gap) are symptoms of attempting to force too much current
through a system limited with a SRG. These problems vary to a
certain extent with the tank circuit used, in particular the
balanced or equidrive circuit responds very poorly.
With the variable speed gap you simply increase the rotor speed,
increase the input current, adjust the rotor speed for the new
current level, and you get more, and longer, sparks. Sure you
will have the gap line up to fire at times when the capacitor is
not at Vmax, at other times the cap will be at Vmax and the gap
will not be lined up to fire. But if you play with your rotor
speed you will find a point where the gap fires very evenly; it
runs smooth and the coil performance is excellent. Enough power
is pumped through the system that long sparks are in continous
production, and when the gap lines up for the "textbook" Vmax
break, the discharge will reach out to cover that extra distance.
High speed photography and still photos where individual pulses
of the rotary gap can be seen in the discharge tend to favor line
of thought.
The only problem I have really had with asynchronous gaps "going
in and out of phase with the charge time of the caps", is when
running a fixed speed rotor on a coil supplied with a fixed
amount of current. There was no way to fine tune the match and
you could both hear and see the effects (not harmful, just not
well tuned) in the gap and in the coil discharge. A synchronous
rotary gap would have sure cured this problem.
Richard Quick
... If all else fails... Throw another megavolt across it!
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