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Re: New System
Tesla List wrote:
>
> > > Subject: Re: Real data from real experiments.
> > Subject: New System, was "Real Data--
> > > Subject: Re: Real data from real experiments.
>
> >From bert.hickman-at-aquila-dot-comSun Nov 17 11:54:32 1996
> Date: Sat, 16 Nov 1996 20:01:24 -0800
> From: Bert Hickman <bert.hickman-at-aquila-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: New System, was "Real Data--
>
>
> Chuck,
>
> I'm definately going to have to see this coil when you're done!!
>
> Your coil parameters look to be in the ballpark! By using a 0.1uF 20 KV
> cap, you'll have twice the energy/bang than if you used CP's next
> smaller size cap. Since CP charges $325 for their 0.05 uF and $450 for
> their 0.1 uF, the latter will double your "energy per bang" for only
> $125 more. As long as you can deliver enough input current to your pig
> to rapidly recharge the cap, you should get spectacular performance.
>
> Some other considerations:
>
> 1. With a 60" x 12" toroid, you'll probably see around 50 pF of
> effective capacitance after taking into account the "shading" from the
> top of the secondary coil. Also, the actual number of secondary turns
> will probably be somewhat less, since its very hard to maintain 100%
> perfectly close winding. I'd multiply the predicted number of turns by
> about 97% or so to compensate for this effect. The combined impact of
> these two factors increases the loaded resonant frequency of your
> secondary - my estimate is about 60-66 kHz. However, once you really
> start cooking, the ion cloud around the toroid should drop it down
> somewhat. I'd size the primary for 60 kHz nominal so that you get about
> 70 uH at a point about 2-3 turns in from the maximum number of turns.
>
> 2. Your primary current will be much larger. Assume you've set your
> system's gaps to fire in the range of 15 KV to 19 KV. Your primary
> energy/bang will be 11 - 18 Joules, and your peak primary current will
> be in the 575 - 725 Amp range. This may require you to beef up the
> design of your rotary (i.e., larger electrodes and forced-air cooling to
> remove the additional heat).
>
> 3. You won't need 15 turns on your primary. If you start the inner turn
> at a diameter 4" larger than your secondary, and use 5/8" or 3/4" copper
> tubing, a 11-turn coil should take you down to about 47 kHz, and would
> let you run at 60 kHz at about turn 8.5. A 15-turn coil would permit you
> to run with a 0.05uF cap, but would offer _no_ other benefit. Unused
> outside turns create unnecessarily high/hazardous voltages at the
> outermost primary turns from autotransformer action. Use only half the
> coil and you'll get 2X voltage multiplication at the outer turn.
>
> Also, if you mount the primary coil assembly on a separate piece of
> plywood with a cutout in the center, you can adjust the coupling fairly
> easily (certainly easier than trying to raise/lower the secondary -
> you'll have almost 36 pounds of copper alone on the secondary).
>
> 4. You probably have to beef up your RF grounding system. The current
> peaks coming out of the secondary's base will be significantly higher
> than before - over 20 Amps. This is probably at least twice what you
> were running before...
>
> 5. The 12" aluminum ducting should work like gangbusters! You can always
> make your system break out wherever you want it too. Its MUCH harder to
> prevent it from breaking out too early - larger ROC is the easiest way.
> Where'd you get yours from?
>
> Hope the above helps!
>
> Safe coilin' to ya, Chuck!
>
> -- Bert --
Bert:
Thanks for your comments, nice to see that my efforts are creating an
interest. When I get ready to smoke test it I'll sure let you know. I
really am shooting for about a 50 Khz resonant frequency at this time.
I'll be sizing the primary with that in mind with the .1 mfd cap. I
really expect it to arrive there based on the results from my other
system. If not, I may end up stacking several toroids for more
capacitance.
I was in the process of modifying the two stationary contacts on my
rotary to utilize Tungsten electodes so the abuse it will take next
spring is a controlling factor on my list of "to do's". I already had
picked up some 1/8" diameter rods but those may need to go to 3/16"
diameter!
Yea, that secondary weight is going to be a bit more interesting. The
form itself is around 40 pounds so the whole secondary will push 75-80
lbs. when wound. I already had a cold shudder thinking of lifting the
finished secondary off of the winding jig, after coating it and then
dropping it!! Murphey's Laws seem to visit on an occasional basis
around here. I plan to be careful. The primary support structure will
be set up for ease of coupling adjustment. I haven't really figured out
the best way based on available (scrounged?) materials yet, but that
will come to the decision point by Christmas. I've got a week off then
and figure on getting alot completed as far as the mechanical side of
things, especially the primary structure and tube forming.
My present RF ground is two 8' copper clad rods about 8' apart coupled
by 6" wide aluminum roofing material, that stuff for going along the
peak of the roof. I figure on adding two more rods with the aluminum
strips coupling all together. I always use one of those 36" watering
spikes and really soak the earth for about 4-6 hours, prior to firing up
the 8" coil. I'll do that too with this one. I really don't know how
much it helped, but the damn grass sure had to be cut alot in that spot!
You asked about the 12" aluminum ducting--I found the 8" stuff at
"Builders Square", but nothing larger. W.W.Grainger, Inc. and/or
McMaster-Carr is where I found the 12" material, along with many other
smaller sizes. Only one had it, soryy the catalogs are laying on my
desk at work and I can't remember which one it was. It wasn't cheap,
they had a 15' length for around $55 and a 30' length for about $99. I
plan to shop around for alternatives too before ordering anything. If
anyone has a better choice for toroid materials, I would love to know
about it.
Thanks alot for your comments Bert.
Chuck