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Re: A Puzzle




From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Wednesday, September 03, 1997 12:23 AM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: A Puzzle

Hi George,

> From:   George W. Ensley[SMTP:erc-at-coastalnet-dot-com]
> Sent:   Tuesday, September 02, 1997 9:36 PM
> To:     Tesla List
> Subject:    Re: A Puzzle
> 
> At 06:45 PM 9/2/97 -0500, you wrote:
> >
> >From:  Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> >Sent:  Tuesday, September 02, 1997 6:03 PM
> >To:    tesla-at-pupman-dot-com
> >Subject:   A Puzzle
> >
> >Greetings All,
> >               This is a genuine enquiry (no, I don't know all the 
> >answers regrettably). Last night, I replaced the large resonator in
> >my work system with a much smaller one with the same sphere on top.
> >I am using the same primary but k would be somewhat different.
> >
> >      The large resonator is a 10" x 44" space wound job (Ctot about 
> >26pF). The small resonator is 4" x 17" and with the same topload 
> >resonates at exactly the same frequency as the large one. This coil 
> >has around 1800 turns of wire one it and consequently its inductance 
> >is much higher (which it would have to be to resonate at 146kHz as 
> >its Ctot is much less than the larger coil). OK, I know the wire 
> >losses are a lot higher in the small one so on to the next bit of 
> >information.
> >
> >     Under single shot conditions, the spark length is pretty much 
> >the same as the large resonator so that implies that output voltage 
> >is pretty much the same. Now that is reasonable because of higher 
> >losses and possibly reduced k probably compensated for by reduced 
> >total capacitance.
> >
> >    The cruncher: The large resonator has created those rare long 
> >sparks measured well over 4 feet p-p. The little one is struggling to 
> >get to two feet p-p. This is with exactly the same primary coil and 
> >cap, energy and gap setting. This situation echoes someone recently 
> >switching from a 3" (?) coil to a 6" one. The air discharges from the 
> >terminal are a bit shorter with the small one suggesting the reduced 
> >capacitance might be a factor. I have not as yet taken any real 
> >measurements but will sometime today.
> >
> >    The question: why?  Any input sought, Ideas welcome from all. 
> >I'd like to hear from anyone, no matter how trivial you think your 
> >contribution might be.
> >
> >Regards All,
> >Malcolm
> >
> >
> >
> Malcolm,
> 
> If this coil was a battering ram i would say it wasn't heavy enough.
> The inertia is either not there or being absorbed by something. I would
> guess a little of both. 

I will check the comparative losses. I think the answer might lie 
there. If inertia = inductance it certainly is there. In fact the 
smaller coil has almost twice that of the large one.
 
> You can't drive an iron spike with a rubber mallet because the peak
> energy is just not there, but all the energy is delivered just the same.

It appears not to be delivered. Same energy is going in. The answer 
might lie in k and/or resonator losses. Those losses are most 
certainly higher in the smaller of the two due to the small wire 
mostly. It is an interesting experiment none-the-less and might
prove to be definitve in determining how much resonator losses really 
matter, even with Q's around 100 or so :)

> I know this is pretty off the wall but i can just see the smaller coil
> crumpling up like a tin can when it slams into the top load.

Well the air streamers off the topload are measurably shorter 
than those I get with the large coil. It breaks out just fine though.
   Ah well, when all else fails bring on the oscilloscope :)

Thanks,
Malcolm