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Re: [TCML] SRSG strobe

I know that using an optical sensor with an oscilloscope provides a very precise way to insure that the flying electrodes line up with the stationary electrodes at whatever phase angle on the 60 Hz power line that you pick on the oscilloscope. Now, whether or not that is the optimum firing point may be a different matter. On my pole-pig powered coil which runs at 240 BPS, the firing angles of 0, 90, 180, and 270 degrees which I set with my oscilloscope did indeed seem to be the optimum. I built a very nice John Freau style phase adjuster to make fine adjustments. When I used it to vary the phase angle from the one that I set with the oscilloscope, I saw no difference in streamer performance or quality. Maybe the effect is much greater with a 120 BPS NST-powered system. Some posters have suggested that a 240 BPS system is closer in performance to a ARSG because it fires 4 times per cycle where firing points may not be as critical.

Steve White
Cedar Rapids, Iowa

----- Original Message -----
From: "Gary Lau" <glau1024@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Monday, October 22, 2018 5:09:07 PM
Subject: Re: [TCML] SRSG strobe

What exactly is the goal here?  Assuming that you're successful in getting
the timing light to sync and fire 120PPS, that still gives no useful
information as to whether the RSG is set to fire at the optimum phase
angle.  The best you can hope for is confirmation that the motor is in fact
synchronous and that the phase can be varied.  I'm unaware of any means to
set the phase other than varying the phase and monitoring spark
performance.  The optimum phase of the RSG relative to the mains phase will
vary with primary cap size and Variac setting, there's no fixed "best"
setting relative to mains peak.  That's why the variable Freau SRSG
controller* is such a godsend - it's always something that you'll want to
tweak.  In my experience, the SRSG phase is super-critical at 120BPS,
there's a clear increase in spark performance as I retard the firing, up
until a critical point, and then it becomes unstable, so I back it off a

As far as protecting the NST, a safety gap in parallel is mandatory in
parallel with the RSG.

For a simpler means of viewing the phase of your SRSG relative to mains
phase, attach a small magnet to the shaft, and mount a small, high turns
count inductor so that the magnet sweeps past it.  Scope the voltage across
the inductor and sync the scope to the line.  You should see induced
voltage blips with each sweep of the magnet, and you should see that
waveform shift as you vary the phase of the SRSG.

*See my RSG web page - http://www.laushaus.com/tesla/sync_gap.htm

Gary Lau

On Sun, Oct 21, 2018 at 11:55 PM Daniel Kunkel <dankunkel@xxxxxxxxx> wrote:

> I'm getting ready to build my phase controller to control my new SRSG. I
> thought I've heard of others use an automotive ignition timing light to
> strobe and watch the phasing, but I can't get mine to trigger off a 60Hz
> source. Can anyone offer some advice here?
> ~Dan
> Kansas City area
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