Re: [TCML] Magnifier topics

[Harvey Norris <harvich@xxxxxxxxx>]

--- On Thu, 2/11/10, Paul Nicholson <tcml88@xxxxxxxxxxx> wrote:

> From: Paul Nicholson <tcml88@xxxxxxxxxxx>
> Subject: Re: [TCML] Magnifier topics
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Thursday, February 11, 2010, 5:26 PM
> Harvey wrote:
> 
> > 47 Turn/ 10 ft Diameter/1500 ft 14 gauge Secondary
> 
> > Now here I will assume that since the secondary
> windings
> > are at 1 inch separation, we can use the quarter wave
> > formula as a good approximation of the secondaries
> resonant
> > frequency using 1500 ft of wire,
> 
> h/d is 47/120 so it will be very different to a regular
> secondary.   Velocity factor with respect to
> wire length
> will be quite a bit less than unity (usually 1.5 to 2 for
> normal h/d).   Outside the range of
> validation of any of
> my models, unfortunately, but I would guess the electrical
> length of the wire will be more like 2000-2500ft when
> wound
> into the secondary.
Thanx for this good advise, I had not considered the H/D ratio aspect at all.
> 
> Predicting the resonance in advance is difficult,
> especially
> when working in terms of wire length.  Plus,
> capacitance of
> the secondary to tertiary connection is unpredictable and
> significant.
> 
> You can use JavaTC to calculate the resonances of each
> coil.
> But these stand-alone resonances are lost when you hook
> the
> two coils together.
> 
> Hence I would say that to get an initial tuning, just
> measure
> the combined secondary + tertiary + topload and tune the
> primary to match.   Use your signal
> generator to find the
> lowest resonance of the system without primary.
> Drive the generator into the secondary base at low
> impedance
> and look for signal peaks on an E-field probe.
> 
> When you have added a primary coil and roughly tuned it,
> maybe you can identify the lowest three resonances with
> the
> signal generator? 
Yes indeed, this can be tried, but my signal generator starts at a low end of 100,000 hz. I think that some local interest in this magnifier project amongst NE Ohio coilers could take place with the following additional speculation, so in the spring I will post a note to list concerning a small teslathon for NE Ohio. It now seems quite a co-incidence that in the building of the elevated insulated dome capacity, I told my builder to employ two, and not merely one insulated wire deliveries to the interior of the dome itself again showed at
http://www.flickr.com/photos/harvich/3933314910/

   He also began to wonder why I also insisted on an independent ground wire path from the neon/dome connection that stands off from the tower by insulated wooden connections by one ft before it is actually grounded to the tower. That modification was made so that in tuning, the ground connection to the tower itself may be broken by the neon  line connection; and certainly this dome to ground connection itself must be eliminated for the actual magnifier operation. In this regard at least two ft exists between the  top ground of the tripod tower itself and the insulated top dome. Thus no outward, but rather downward arcing to supporting grounded structure is projected to occur from the dome itself. The presence of the line connected  4 inch neon tube under the dome will un-doubtably aid in tuning, and perhaps its ungrounded operation will aid in additional fine tuning using lower power input levels. The somewhat fascinating possibility brought forth here
 by Paul Nicholson is that since it is indicated that two different modes of  3/4 wave vibrational differences may exist in the magnifier; and since independent polar capacity delivery lines exist for the dome; two independent tertiaries operating with common connection  from the the ending secondary connections might be tried in simultaneous operation from the secondary source. At my disposal is two of the two ft height secondaries of 1790 ft, and three of the one ft ht/ 900 ft wire length ones, where these can be mounted with wooden platform additions on perimeter of the secondary supporting posts. The obvious complication here is that it may be unfeasible for both vibrations to share the same topload.
HDN

  Then, it is a matter of
> fiddling with the
> primary and transmission line capacitances to set the
> ratios of
> the frequencies to one of the desirable combinations
> described
> by Antonio.
> 
> Well, others may have better suggestions Harvey.  I
> don't have
> any practical experience of magnifier tuning.
> 
> --
> Paul Nicholson
> --
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> 



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