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Re: Interesting but not so impressive results...
From: Phil Chalk[SMTP:philoc-at-ozemail-dot-com.au]
Sent: Monday, September 08, 1997 5:35 AM
To: Tesla List
Subject: Re: Interesting but not so impressive results...
Tesla List wrote:
>
> From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> HI Rod,
> Well that was a bit of a disappointment.....
>
> > From: Rodney Davies[SMTP:rgd872-at-anu.edu.au]
> > Subject: Interesting but not so impressive results...
> >
- Big snip. -
> >
> > Perhaps a diagram may help explain...
> >
> >
> > Secondary.
> >
> > _________
> > | | <---- started to become brighter.
> > | |
> > | |
> > | |
> > | | <----- virtually no corona
> > | |
> > | |
> > | | <----- brightest.
> > | |
> > | | <----- earth wire ---+
> > | | medium brightness |
> > --------- ---
> > Base. \\\
> >
> >
> > I guess this is an indication of what the wave is doing...
> >
> > Also, there could be alot of contributing factors -
> > 1/ zero quenching on the single-static gap
> > 2/ completely out of tune
> > 3/ No toploading
> > 4/ primary circuit no where near in resonance
> > 5/ secondary re-coupling energy back to primary
> >
> > etc..etc...
> >
> > But, I'm sure I'll fix it up soon, just need more money...
> > Some, if not most of you will agree, big coils are an expensive hobby! :-)
> >
> > Anyway, I was just wondering if anyone would like to elaborate on the
> > corona effects I observed with the secondary?
>
> Be happy to. My reading of that is that you tuned to the second
> harmonic and the response will be appalling from a coil that size. Hi
> Q resonators are pretty narrow band in response. Your gap will be
> taking a beating I'd think. Rather than increasing the primary cap,
> how about increasing primary L. You won't get the best from you
> supply with a static gap but I think you'd be pleasnatly surprised at
> the results.
>
> Malcolm
>
> > Yes, I know, never arc to the windings...but it's a really bodgy coil, so
> > I guess it really doesn't matter...
> >
> >
> > Thanks Guys!
> >
> > Have fun!
> >
> > Catchya!
> > Rod
> >
> >
> >
Glad one of "the gurus" beat me two it, but that was going to be my
guess - a 2nd harmonic. When I first got sparks out of my first coil, I
couldn't help thinking, well this point (primary tuning) is clearly
_some kind_ of resonance but is it _the right one_, the fundamental. I
knew something about my secondary, & ac supply & cap, etc, but the
primary was just "start about here & keep winding till you run out of
copper, and see if it'll tune somewhere in between". Ended up with 12
1/2 turns, & tuned around 6, but I never calculated anything about the
primary. My HP606B (sig gen) is about 10 years deep inside Mum's garage,
but one day soon....... All will be revealed. Having seen photos of
yours, the primary looks (to my inexperienced eye) very small relative
to the secondary size.
P.S. Glad I didn't travel 350 ks for 5" sparks this weekend !!! See ya
soon, probably weekend of 13/14th Sept. ? Mail you privately.
Cheers,
Phil Chalk.