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Re: Simple DC starter stuff

Tesla List wrote:
> 
> >From gchristo-at-clt.mindspring-dot-comMon Nov 18 20:07:06 1996
> Date: Mon, 18 Nov 1996 14:50:42 +0000
> From: Chris Gardner <gchristo-at-clt.mindspring-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Simple DC starter stuff
> 
> > Welcome back to coiling! The very first coil I built was much like
> > yours, almost 40 years ago :^( , only with a cardboard former. I don't
> > know if they'd even invented PVC way back then... :^).  It turns out
> > that you have tremendous latitude in re-building your coil. Its only
> > when want to push higher power levels, voltages, or efficiencies that
> > the "design rules" start to become more restrictive.
> >
> > Lets cover the basic areas, and throw in minimal design considerations.
> > The major areas areas and cover them in a little more detail:
> >
> >  1. HV Supply
> >  2. Tank Capacitor
> >  3. Primary Coil
> >  4. Secondary Coil (Resonator)
> >  5. Discharger
> >  6. Spark gap
> ...
> 
> ...
> > Safe coilin' to ya!
> >
> > -- Bert --
> 
> Thanks dude!         I appreciate the copious info!
> 
> Could I clarify a couple of points?
> 
>  - My orriginal CAP was constructed using silicone rubber as the sealant
> / glue to hold it all together, is this still the best option? (for this
> power range)
> 
Shouldn't be a problem. If you don't secure the plates to the glass
somehow, they'll vibrate, make somewhat more corona and ozone, and will
give you lower capacitance/performance.  

>  - The spark gap you mentioned, do I read that correctly that the
> sections of copper pipe should be parallel? thus the spark should leap
> from rounded surface to rounded surface, do I need to worry about the
> cutoff edges?

Yes, you read correctly. You may want to round the edges on the ends to
reduce the incidence of arcing at just the ends.  At the relatively low
power level you'll be running, even a pair of large carriage bolt-ends
would be satisfactory.  
> 
>  - What is the best way to connect the secondary to the toroid,
> specifically, the transition from the coil to the physical connection to
> the torroid; should I avoid tight bends or crimps? Is connection to the
> center of the torroid prefferable to the edge directly above the top of
> the last winding of the secondary?

Glue a 1/8" or 1/4" plexiglas top plate to the coil form using epoxy
cement, and glue a 1/2" thick block (or 2-1/4" pieces glued together) of
plexiglas on top of this. The 1/2" plexiglas is drilled and tapped for a
1/4-20 nylon screw. This bolt secures a small flat PVC end-cap
positioned with the open-end up to the top block. A similar arrangement
is used to secure a center plate which is taped to the inside of the
toroid, and a matching PVC end cap pointing downward. By using various
lengths of PVC pipe, you can easily adjust the height of the toroid
above the coil. Use a small bolt, 2 washers and a wingnut to
electrically connect the secondary top wire to the toroid. Simply make a
lazy spiral with the wire coming off the coil, and secure the free end
to the underside of the toroid plate with the wingnut. As long as the
wingnut and bolt (x) are significantly above the lowest portion of the
toroid, you should be OK. The exact position is not critical. A rough
ASCII sketch is shown below.


     O                   0
   O   O------^------^-O   0
     0      |   |    X   0
            |   |
            |   |
            |___|  
           |     | 
         -----------        
         -----------
         |         |
         |         |
         |         | 

> 
> ok so it was more than a couple.....   thanks

No problem! Good Luck and safe coilin' to ya'!!

-- Bert --