When talking about NST-powered SRSG setups, setting the SRSG phase
controller to fire at the peak charging voltage of the cap is close, but
still not optimum. While intuition suggests that firing at the peak
voltage cap is the obvious target, if you were to do so, the subsequent
cycle's peak capacitor charging voltage won't be as high. Circuit
simulations and experimental scoping confirm that the greatest bang
voltages are achieved when firing as the cap voltage declines slightly past
its peak voltage. My scoped waveforms are at the bottom of my SRSG web
page: http://www.laushaus.com/tesla/sync_gap.htm illustrate this. But
really, just use a Freau phase controller and adjust for the best
performance at any given power Variac setting. Scoping is only necessary
to convince yourself that the world is a very complex and non-intuitive
place.
Also note that cap voltages got to about 30kV in these experiments(!). I
think I deliberately opened up my safety gap for smoother scoping and the
sake of science. Do as I say and not as I did, please use and trust safety
gaps.
Regards, Gary Lau
MA, USA
On Mon, Sep 28, 2020 at 7:21 AM <jan@xxxxxxxx> wrote:
> Hi Shaun,
> It is possible to take scope measurement of the capacitor voltage, with the
> timing of the spark gap visible. This is a much more direct way of
> assessing
> the timing. The capacitor voltage is difficult to measure directly, but if
> you use a differential HV probe like the Micsig DP10013, which sells for
> about 160 $, on the transformer primary, the waveform is almost identical
> to
> the capacitor voltage (multiplied by the winding ratio, of course). Then
> you
> will see where the timing of the SRSG falls on the charging cycle of the
> cap. You will also see the capacitor voltage at the firing, so you can see
> to what extent your charging is optimized.
>
> I have simultaneous measurements on my web site of cap voltage and
> transformer primary voltage waveforms, that shows that the waveforms are
> virtually identical. But this is only valid for externally ballasted
> transformers with low leakage inductance, like a pig. For a NST you will
> only get a meaningless mains waveform, as the ballast inductance is
> included
> in the transformer.
>
> https://www.sthlmteslacoil.se/measurements.html
>
> Regards,
> Jan
> Stockholm, Sweden
>
>
>
>
>
> -------------------------------------------------------------
> Date: Tue, 15 Sep 2020 12:35:00 -0400
> From: "shaun" <snoggle@xxxxxxxxxxxxxx>
>
> To: <tesla@xxxxxxxxxxxxxxxxxx>
> Subject: [TCML] Excited
> Message-ID: <000701d68b7e$2838a770$78a9f650$@com>
> Content-Type: text/plain; charset="us-ascii"
>
> After reading several post about setting the John F phase controller seems
> many are incorrectly setting the timing to the peak ac mains, as was I. You
> guys straightened me out and I have restudied Richie B, web site and now
> know to set the firing to peak of the charging cap, at least that what I
> understand at the moment. Im pumped to try the correct method out. Have one
> question, is there a easy way to find the peak of the cap, seen some just
> going by ear. With only 45 degrees of phase movement could take a bit of
> lock and unlock, would like to be in the ball park.
>
>
>
> My initial idea is use a ct to trigger off the primary. Thank any for there
> insight.
>
>
>
> *********
>
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>
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