# RE: QUESTION FROM THE PAS

• To: tesla-at-grendel.objinc-dot-com
• Subject: RE: QUESTION FROM THE PAS
• From: richard.quick-at-slug-dot-org (Richard Quick)
• Date: Fri, 10 Feb 1995 23:42:00 GMT
• >Received: from uustar.starnet-dot-net by csn-dot-net with SMTP id AA06921 (5.65c/IDA-1.4.4 for <tesla-at-grendel.objinc-dot-com>); Fri, 10 Feb 1995 20:49:59 -0700

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> From: EDHARRIS-at-MPS.OHIO-STATE.EDU
> Subject: Re: QUESTION FROM THE PAS

EH> Thanks for the feedback, Richard.

EH> I suppose that what I was really interested in was whether or not
EH> anybody is working on the mathematical modeling of Tesla coils,
EH> especially the secondary itself. I know you guys have a lot of
EH> experience in picking optimal parameters for coils such as:

EH> Coils should have aspect ratios of 3/1 or perhaps 5/1 (L/D)

Depends on the secondary coil form diameter, and the size and shape
of the primary. Most people here are building 4-6 inch diameter coils,
and I am advising that people stretch the secondaries a little to get
a bit more inductance, then use more turns on the primary to couple
evenly.

EH> Coils should be tight wound (none of the "double-spacing" with
EH> fishing line as recommened in some old designs.

Absolutely. Inductance, inductance, inductance!

EH> Coils should have roughly 1000 turns (is this correct?)

Roughly between 900 - 1000. Too much over 1000 turns in close
wound magnet wire coils and the distributed capacitance and RF
resistance begin to rob the coil of Q; but too much under 900
turns and the coil lacks inductance.

EH> Etc....

EH> I'm interested in accurate math models which can predict this
EH> behavior. Perhaps the models could then be used to point to
EH> improved designs....?  Anyone else interested in this subject?
EH> I'd be interested in a collaboration. Personally, I've never
EH> come across any serious mathematical attacks on Tesla coil
EH> design. The most I've seen is some work on helical antennas
EH> which is only semi-applicable to real Tesla coils...

Ed, I can't add an odd and even number in my head. The work you
may be looking for, or at least the place where I would start if
I were you, would be in Corum & Corum: VACUUM TUBE TESLA COILS.
mapped out in this book.

> VACUUM TUBE TESLA COILS
Corum & Assoc, Inc., 8551 State Route 534, Windsor, Ohio, 44099,
USA. ISBN 0-924758-00-7. Tesla Math, tube coil circuits, theory.
This book is geared more for the advanced coiler with some
knowledge of calculus, but offers enough for the beginner to be
on the "read" list. This book is a guide to the significance of
Tesla's Extra Coil work, the infamous lab at Colorado Springs,
and the history of resonators. Many charts are easily understood.
(My review pasted in from the Tesla reference file. RQ)

The key here is that the Tesla coil is a resonator, not an
antenna. The Corums note that "Tesla's work proves to be totally
incomprehensible to a lumped circuit engineering mentality." But
they document some success when using traveling wave engineering;
specifically the mathmatical modeling of distributed resonators
"- whether they be constructed as coils of wire, lengths of trans-
mission line, cavity resonators or even optical resonators - all
are specific embodiments of the phenomenon of resonate rise by
standing waves, as discovered by Tesla 100 years ago. And, all
inherently possess the capability to raise the electric field
intensity to the point of media breakdown with an ensuing specta-
cular production of electric fire."

You would love this book.

Richard Quick

... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12

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