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RE: Results of new single static gap

At 07:36 AM 9/2/98 -0400, you wrote:
SNIP........
>From: "Thornton, Russ #CSR2000" <ThorntoR-at-rc.pafb.af.mil>
>
>This is what I would expect.  Do you have a way to measure on a scope 
>the relative spark time to the 60 Hz sine wave? I would intuitively expect
>that as you increase the gap the spark time would climb up the first half
>cycle.
>

Hi Russ,

I can easily connect one channel to a small AC transformer and the other to
the primary cap voltage probe.  However, it will be ugly!  Let me explain.

When the gap fires in the early part of the waveform, it discharges the
primary cap and resets the voltage to zero.  Then the cap will start to
charge for a short time but the AC will reverse before it can fire again.
Now the cap voltage must discharge that charge and begin to charge in the
opposite polarity.  Soon it will get to firing voltage and this will
repeat.  The problem is that the voltage hump after the gap fires needs to
be discharged before the cap can begin charging in the proper polarity.
This hump's size has a dramatic effect on the timing relative to the line
AC voltage.  The hump is also very sensitive to the firing voltage and the
open load voltage of the charging circuit.  The resonant effects between
the neon and the primary caps also add another significant factor.  Also,
the gap firing jitters a bit which amplifies the effect greatly.  So the
firing time is all over the place relative to the line AC.  Increasing the
firing voltage allows the cap to charge longer but there is too much
"noise" to make the timing to the AC very useful.  

I haven't specifically done this test but I think this is what one would
see.  This is a very important subject and needs to be studied in great
detail.  I am short of time at the moment, but if doing this experiment
will be of use let me know (off list is fine) and I will work it in.

I assume rotary gaps control this timing much better than a static gap.  I
don't have a sync gap (yet) to try this with :-(  I need to go to the motor
shop for wire soon and I will ask if they have any sync motors.  

	Terry Fritz