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Re: [TCML] Oscilloscope Tuning



You can also use my Tesla coil tuner to dynamically tune your coil while it
is running.  You can use a scope or high impedance digital voltmeter.

Dr. Resonance





On Wed, Dec 24, 2008 at 9:05 AM, Phil Tuck <follies@xxxxxxxxxxxx> wrote:

> Hello.
>
> I have just tried a method of tuning the coil using a 'scope and signal
> genny, that was suggested in the archives by Antonio Carlos M. de Queiroz .
>
>  I had already tuned it in the 'normal' fashion of injecting a signal in
> the
> base of the secondary and hanging the probe close by. The secondary &
> toroid
> were  mounted in their usual place but the SG was left open circuit  to
> avoid the primary LC affecting things.  I also tried it with the
> secondary/toroid well away from the primary just to 'be safe' and the
> result
> looked on the scope to be the same.
>
>  I do not have a frequency counter so I get the resonant peak on the scope,
> and then connect the scope across the signal genny to get a truer result of
> the frequency rather than reading the [rather course] dial. So small
> differences won't show as the scope's 'eyeball' resolution is limited to
> around 0.1 divisions.
>
> I had also hung a piece of wire to the toroid  to simulate a streamer. [The
> difference between simulating a streamer and without one a drop of around
> 18kHz - 156.25 down to 138.88  kHz  a drop of  11.1%]
>
>
>
> The primary was then checked with the SG shorted and the genny and 'scope
> across the inductor/caps. The secondary was removed completely for this
> part
> though. After some adjustments to the tap point,  both resonant frequencies
> were the same [secondary with a simulated streamer].
>
>
>
> I then tried Antonio's method of placing a 1.5 ohm resistor across the gap
> and connecting the signal genny in parallel to it running at 1Khz square
> wave output. The secondary and top load were connected and back in place,
> whilst the NST and Terry were disconnected. The scope was placed across the
> primary coil.
>
>
>
> The resultant trace can be seen here:
> http://homepage.ntlworld.com/follies/temp/scope.jpg
>
>
>
> It looks like it may be correct as I can see what I presume to be the
> ringdown, but I remember seeing a scope trace somewhere else on the web
> where the abrupt sharp Y axis rises that I have, were replaced with  more
> gradual 'ringup' shapes, so I wondered what anyone else on here thought.
>
>
>
> Both my 20 year old scopes are the limiting factor most likely as
> decreasing
> the time base makes the trace even more noisy and unreadable.
>
>
>
> As a point of interest the signal genny output was around 15 - 20  volts
> and
> the scope timebase is 0.2 millisecond giving what I suppose [bear in mind
> that the primary was running on 15 volts with no spark gap needing to fire]
> would be an equivalent break rate  of around 1/( 2.4 x 0.0002) = 2083 bps.
>
>
>
> Regards
>
> Phil
>
>
>
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