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Re: Single Shot




From: 	Peter Electric[SMTP:elekessy-at-macquarie.matra-dot-com.au]
Reply To: 	elekessy-at-macquarie.matra-dot-com.au
Sent: 	Friday, August 08, 1997 5:17 AM
To: 	Tesla List
Subject: 	Re: Single Shot

Tesla List wrote:
> 
> From:   Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> Sent:   Thursday, August 07, 1997 12:55 AM
> To:     tesla-at-pupman-dot-com
> Subject:        Re: Single Shot
> 
> Hi Julian,
>             Thankyou, thankyou for going out and *trying* these tests.
> I am over the moon that somebody has *done* it rather than sit there
> and speculate. I am extremely indebted to you. You have made my day :)
> 
> > From:   Julian Green[SMTP:julian-at-kbss.bt.co.uk]
> > Sent:   Wednesday, August 06, 1997 12:30 PM
> > To:     tesla-at-pupman-dot-com
> > Subject:    Re: Single Shot
> >
> > Thankyou Malcolm for your post I have repeated the scope tests
> > you describe and have observed the same.   The mark space ratio of a
> > running coil clearly shows that the secondary is at complete rest before
> > the next bang, thus disproving the idea that the energy in a ringing secondary
> > is from multiple bangs.   Taking a closer look of the waveform when the coil
> > is allowed to produce streamers shows that all the energy in the secondary is
> > transfered into the streamer on the first half cycle of RF (on my coil).
> 
> I would expect something like that at higher power levels :)
> 
> > Coil running - no streamers.
> >
> > Low scope time base looks like this:
> >
> >      |     |     |     |     |     |
> > -----+-----+-----+-----+-----+-----+----
> >      |     |     |     |     |     |
> >
> > Each spike being a firing of the gap.
> >
> > Faster time base using +trigger and you get this, only
> > many more cylcles and shows nice decay.
> >
> >      /\
> >     /  \        /\
> >    /    \      /  \    /\
> > ---      \    /    \  /  \-------
> >           \  /      \/
> >            \/
> >
> > When grounded rod used to generate streamers output looks like:
> >
> >         /|
> >        / |
> >       /  |
> >      /   |
> > -----     ------------------
> >
> >
> > You dont need a storage scope to get these, just a cheap 20MHz scope
> > with HF trigger.   Connect short length of wire to scope probe and
> > set up away from the coil.   Good traces are visable on the 20v/div
> > scale.   For your single shot tests adjust input power to obtain
> > intermittent firing of the spark gap.
> >
> > Peek voltage or trace amplitude is at a maximum when no streamers are
> > being produced.
> >
> > I assume that the coupling between scope probe and TC is capacitive.
> 
> It is.
> 
> Many Regards,
> Malcolm

Julian/Malcolm

Thanks for the info on how to set up the scope. Previously I have not
been game to run my scope near the coil but I thought, what the heck! if
it blows up I'll have an excuse to by a fancy new scope. No such luck
though, my results were exactly the same as yours, there is a "huge!"
length of empty trace between successive rings of the secondary yet the
sparks still continue to grow.

Just a question for you experts, in the single shot tests, does the old
10kV per cM of spark (25kV per inch?) rule still apply?

Cheers, Peter E.