Re: RE- Hello from a new coil

From: 	Robert Michaels[SMTP:robert.michaels-at-online.sme-dot-org]
Sent: 	Tuesday, August 05, 1997 2:40 PM
To: 	tesla-at-pupman-dot-com
Subject: 	RE- Hello from a new coil

        Welcome aboard!

        I'll comment on a few of your inquiries and leave it to others
        more knowledgeable than I (most on This List) to tackle the

T>From:  Sulaiman Abdullah[SMTP:sulabd-at-hotmail-dot-com]
T>Subject:  Hello from a new coiler.

[ ... ]

T>I've loads of questions so I'd really appreciate some help.

T>1  My coil is wound on a nominal 4" uPVC pipe
T>   0.7mm magnet wire, 33 turns per inch
T>   108mm actual winding diameter (4.25")
T>   576mm actual winding length  (22.67")
T>   753 turns total
T>    11mH measured
T>   14ohm measured
T>   Heavily coated with polyurethane varnish
T>   Warmed to 60 C (140 F) for one week to reduce moisture

        All wound on the same 4" piece of pipe?  All with the same
        gauge of wire?   It's unconventional.  It might work, or
        you might get some really pretty arcing from primary to

        Or is the primary joined to the secondary, thus forming a
        sort of Tesla autotransformer (a.k.a. an Oudin (gaakkk!)

T>   Is this workable or do I REALLY need to start again with a larger
T>diameter former ?

        What you really need, IMHO, is a primary  =and=  a
        secondary coil.  As separate structures.  With wire
        sizes appropriate to each.  (You seem like a nice fellow,
        stay away from that Oudin stuff [This is the TESLA List!] ).

[ ... ]

T>3  Could someone explain spark-gap quenching to me ?
T>   I'd REALLY appreciate a photo, .gif, .jpg etc. or even a
T>description of waveforms and voltages.

        There isn't much to explain, and it doesn't require
        GIFs, JPGs or waveforms (or .PCXs or .DWGs or phase
        plots, or smith charts, or venn diagrams either)

        The performance of a Tesla coil is much enhanced if
        the spark (in the spark gap) is extinguished as quickly
        as possible.  Period.  End of explanation.

        "Quenching" merely refers to putting out that spark
        as quickly as possible.  Such can be accomplished in-
        trinsically (as in the design of the gap) or extrinsically
        (as by air currents, mechanical motion, magnetic fields,
         etc.) or both.  Period.  (again)

T>4  I'd like to operate at low-frequency / high top-capacitance,
T>   is it necessary to operate at the quarter-wavelength frequency ?

        There's no such thing:  "quarter-wavelength frequency".
        Wavelength is one property of an electromagnetic wave.
        Frequency is another property.  They are separate entities,
        tho related to each other by a constant of proportionality
        (which is called the "speed of light").

        The secondary of a Tesla coil is customarily designed to
        be a quarter-wave in length.  Such puts a voltage node
        at the business end of the secondary.  That's what most
        builders want:  Voltage.  And at the business end of the
        coil.  (As opposed to coming out the middle somewhere).

                There was a famous bank robber in the U.S. by
                the name of Willie Sutton.  When he was finally
                captured he was asked why he went about robbing
                banks.  His reply:  " 'Cause that's where the
                money is".

                It's the same with quarter-wave secondaries:
                The quarter-wave point is where the voltage is.

[ ... ]

T>   Don't toroids and guard-rails form an effective shorted-turn ?

        Guard-rails:  You don't let them do that!!  (Same idea
        as [not] letting a two-year-old play with matches).
        Guard-rails  =always=  have a gap in them to prevent
        forming a shorted turn.

        Torouses are not turns.  They are a load for the resonant
        system to work into.
                 Roughly akin to the antenna on a
                 radio transmitter - the antenna does not
                 "short-out" the transmitter.  Rather it greatly
                 assists projection of the rf energy into the ether.

T>Thanks for your endurance reading this long e-mail !

        Likewise, my response.

T>I will really appreciate all your responses.

        Oh?  Obviously you wrote that  =before=  reading my
        reply ;->

                         - - - - - - - - -

        I've a question for you, please:

        Is gutta percha readily available (or available at all) in

                                        Attempting to coil where
                                        no men have coiled before,
                                        in -- Detroit, USA

                                        Robert Michaels