From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: Tuesday, September 02, 1997 6:03 PM
Subject: A Puzzle
This is a genuine enquiry (no, I don't know all the
answers regrettably). Last night, I replaced the large resonator in
my work system with a much smaller one with the same sphere on top.
I am using the same primary but k would be somewhat different.
The large resonator is a 10" x 44" space wound job (Ctot about
26pF). The small resonator is 4" x 17" and with the same topload
resonates at exactly the same frequency as the large one. This coil
has around 1800 turns of wire one it and consequently its inductance
is much higher (which it would have to be to resonate at 146kHz as
its Ctot is much less than the larger coil). OK, I know the wire
losses are a lot higher in the small one so on to the next bit of
Under single shot conditions, the spark length is pretty much
the same as the large resonator so that implies that output voltage
is pretty much the same. Now that is reasonable because of higher
losses and possibly reduced k probably compensated for by reduced
The cruncher: The large resonator has created those rare long
sparks measured well over 4 feet p-p. The little one is struggling to
get to two feet p-p. This is with exactly the same primary coil and
cap, energy and gap setting. This situation echoes someone recently
switching from a 3" (?) coil to a 6" one. The air discharges from the
terminal are a bit shorter with the small one suggesting the reduced
capacitance might be a factor. I have not as yet taken any real
measurements but will sometime today.
The question: why? Any input sought, Ideas welcome from all.
I'd like to hear from anyone, no matter how trivial you think your
contribution might be.