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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.