RE: [TCML] Oscilloscope Tuning

["Phil Tuck" <follies@xxxxxxxxxxxx>]

Hello Antonio
Yours is the image that I referred to in my original post, I could not
remember where I had seen it though.
However seeing it again I realise how different mine is. 
You say that you don't necessarily have to connect in parallel with a
resistor across the SG to do this, as the usual method of a probe hanging
near the secondary will also suffice. That would rule out my resistor being
too high a value as I had actually tried the probe method the second time as
well out of curiosity, and although I can't actually remember now what I
got, I do know it was not your pattern that you show as an example!
As mentioned I had initially already used the 2 stage tuning method prior to
using your method, so it should have been nearly in tune, but I did not try
moving the tap when using your method, maybe I need to.

I took the bulk of the coil apart this afternoon to move the [sucker] SG to
a different location (I'm enclosing it for sound insulation), so I can't
test again for a few days, but I will post the outcome when I do it.

Regards
Phil


-----Original Message-----
From: Antonio Carlos M. de Queiroz [mailto:acmdq@xxxxxxxxxx] 
Sent: 26 December 2008 13:05
To: Tesla Coil Mailing List
Subject: Re: [TCML] Oscilloscope Tuning

Phil Tuck wrote:
> 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.
>   
You have to expand the time axis to see the transients immediately after 
the transitions of the
square wave, and tune the system so complete beats are seen.
Over the primary coil:
http://www.coe.ufrj.br/~acmq/tesla/vc1910.jpg
 From a probe close to the secondary terminal (anywhere, actually):
http://www.coe.ufrj.br/~acmq/tesla/vc2910.jpg

You may have to use a smaller resistor.

Antonio Carlos M. de Queiroz




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