RE- Secondary wire & insu

Subject:      RE- Secondary wire & insu
       Date:  Wed, 04 Jun 1997 08:07:00 GMT
       From:  robert.michaels-at-online.sme-dot-org (Robert Michaels)
Organization: Society of Manufacturing Engineers
         To:  tesla-at-pupman-dot-com

        Apples and oranges, again.  (Why always those particular fruits,
        why not, say, persimmons and mangos)?   I sort of agree with Mr.
        Skrocki, and I sort of don't.

        -- Making a space-wound coil using a closed loop (as a
                spacer) with a weight attached is effective, but I'd
                scarcely say it is "easily" done.  In fact it precludes
                any machine or power-driven winding of a coil.

                In my experience, the closed, weighted loop is best
                made itself of magnet wire.

        -- To compare wire enamels of 1907 (or whenever) to those of
                1997 is truly to compare persimmons and mangos.
                "Back then" they were little more than furniture
                varnish, their high-frequency electrical characteristics
                were ...?!?!?.   Today, wire enamels are specially
                designed and formulated for optimal electrical
                characteristics; it's a whole technology in itself.

        -- In all but the highest powered Tesla coils, the volts-per-
                turn of the secondary is apt to be below the breakdown
                voltage of the wire enamel.

                Consider:  A 500-Kv coil having a thousand turns
                           in it's secondary  (Love those round num-
                           bers!).   That's 500-volts/turn.

                        Which means, the wire enamel must withstand
                        250-volts. Not a major challenge for today's
                        wire enamels.   Comprendo, compadre - 250-v.?

                        (Hint: Adjacent turns have  =two=  layers of
                        wire enamel between them, one on each of the
                        two wires:  500/2 = 250-volts. )

        Wire enamels are available in a wide variety of types (and
        prices!) and one must specify knowledgeably.

                                - - - - - - - - -

        This is not to say Mr. Skrocki (or Mr. Curtis) is wrong.  Not
        at all.  (If nothing else, DCC wire really looks cool when
        wound into a coil -- and I favor gutta percha myself! - ooohh!).
        I'm just here to say that wholesale dismissal of the
        entire field of modern wire enamels may be a bit hasty.
        (That, and use a weighted loop of  =wire=  when space-winding
        that coil).

                                        Keepings those windings
                                        straight, in -- Detroit, USA

                                        Robert Michaels

T>   Begging to differ here, most small commercial induction coils were
T>wound with bare wire and many a tesla coil have too, you just have to
T>space the wire and that is easily accomplished by making a loop of
T>thread the same thickness as the wire you are using and put a 1/4 to
T>1/2 oz. fishing sinker on the loop and wind the coil with the loop
T>between turns it will keep the spaceing. The insulation on the wires

[ ... ]

T>turns thus insulating the coil better. As a mater of fact to quote
T>Thomas Stanley Curtis in his "High Frequency Apparatus" he states;

T>       "The conductor for the secondary windings of all types of
T>    oscillation transformers should be of soft, pure copper wire.
T>    The insulation may be of cotton or silk but NOT of enamel. The
T>    use of the later for high frequency secondaries has given the
T>    author great dissapointment in the construction of several large
T>    and comparatively expensive coils. The insulation on the wire is
T>    of no value whatever except to provide a mechanical separation
T>    for the turns of wire and to form a base or support for whatever
T>    insulating substance is applied to the wire subsequenty."