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Re: Beginner's coil safety

Hi Doug,

	This took me a moment to "get" :-))  You calculated 5 miles by taking the
speed of light and dividing by 8300 Hz to get the wavelength which is 22.5
miles.  The 1/4 wave wavelength is 5.6 miles.

	My best guess using a magnifying glass and calculator is that there is
about 1.5 miles of wire on the secondary.  I do not believe the 1/4 wave
theory of Tesla coil tuning or that wire length has anything to do with a
coil's resonant frequency.  I think the resonant frequency of the secondary
is governed by the secondary's inductance, it's self capacitance, and the
terminal capacitance.  If you hook a signal generator to a Tesla coil
secondary you can easily get a 1/4 wave resonance.  However, it will not
have anything to do with the wire length.  In a real situation you would
have to load the output with an ~220000 ohms and a few pF of capacitance to
simulate the arc losses and also pulse the secondary.  Under these
conditions, the losses are too high and the excitation time to short to set
up a resonance.  This is also why I do not think the Q of the secondary has
much meaning.  Testing I have done has also shown that the current at the
base and top of the secondary are in phase.  This directly disproves the
standing wave theory.  See:

http://www.peakpeak-dot-com/~terryf/tesla/experiments/topsync/topsync.html

	This paper describes the testing in detail.

	In other news...  I bought and ripped apart a Kodak MAX Flash disposable
camera and I think the flash circuit will charge my little Tesla coil for
about a 1BPS output at 300 volts.  The flash unit charges the flash to 8
joules in about 1 second (320V 160uF).  I should be able to put a resistor
and such on the output to get a charge of 300 volts on my 1.7uF primary cap
with overheating the flash unit.  Still more to do but I got the camera for
$7 on sale which is good for an HV supply.  One may be able to get them
free from the photo shop too.  These things do pack quite a bit of power
and great care is needed in working with the flash unit!

	I keep hearing that someone has a system where two GM coils are putting
out 3 foot arcs!  This would make me relinquish my coveted GMHEICSLR if
true (unless I turn my system up to 1750 volts :-)).  However, no one seems
to have any hard information on who, their e-mail address, web page, etc.
to confirm this....  If anyone has any hard evidence let me know.  Send any
hard information on this directly to me since it is not really a big deal
subject for the list.  If it is true, I will announce the details.  They
would have to be using much the same techniques I am using and their
results would be valuable to add to this project.

BTW - I have the cross section of the GM coil scanned.  E-mail me and I
will send anyone the *.JPG file.  It is 170k.

	Terry
	terryf-at-verinet-dot-com




At 09:15 PM 11/18/98 -0500, you wrote:
>Beginner's coil? With, by my calculations, about 5 miles of wire?
>
>           --Mr. Postman (Doug Brunner)
>                <dabrunner-at-earthlink-dot-net>
>-----Original Message-----
>From: Tesla List <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
>Date: Wednesday, November 18, 1998 8:48 PM
>Subject: Beginner's coil safety
>
>