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Interesting Effects
Hello All,
Playing around with my 8" coil I have noticed something interesting
(probably been seen before and commented on) and would like to hear some
comments on it. My main gap is set so that I do not need the full power
setting on my variac. The spark gap will start to fire somewhere around the
80% (Variac is a 0-250V model) setting. After the gap begins to conduct I
can reduce input voltage (to about 60% on the variac). This doesn´t
come as a surprise to me, but I have noticed the following:
a.) Reducing the input voltage until the gap is on the ragged edge of
conduction, will get me less streamers, but they are a lot longer and very
lazy.
b.) Going higher than the 60-65% (to about 80% meaning ~220V) setting gets
me shorter streamers, but more of them. Their speed doesn´t change
much, tho.
c.) "Overvolting" the NSTs (they are designed for 220V, and I am "giving"
them 255V. They do NOT saturate at this voltage, I have checked this)
doesn´t get me any more streamers and does not change their length.
However, they start swirling around the toroid like crazy (about once
around every second or two).
Now, this is a surprise to me. I figure that at the 60% setting I must have
the lowest BPS rate, while at the other end of the scale (255V) I must have
the highest BPS rate. The noise that the spark gap makes would support this
theory. (More power in = faster recharge rate). >From what I have heard
(haven´t built my RSG yet) going up in BPS rate will get you longer
sparks (otherwise why would coilers do this?).
Before I forget: I am using a 7.5kV NST with 75mA and a 25.5nF cap. The
25nf cap is about 80% of the capacitance necessary for resonant charging.
The results (a thru c), however, will work with any cap value I have used
so far (9,10,12,15,20nf). I did retune the priamary for every cap used. Of
course, the more capacitance used, the longer the sparks get, but the
effects are the same.
WHY?!?!?
Coiler greets from germany,
Reinhard