Re: [TCML] Coil V1.0 Arc over between turns of secondary.

[Brandon Hendershot <brandonhendershot@xxxxxxxxx>]

> I undid this.  He had drilled holes in the secondary tubing, and  
> inserted the wire ends on the top and bottom.  I pulled these out,  
> plugged the holes with epoxy.  I made plugs for the top and bottom  
> from 1/2" thick sheets of gray PVC as Dan's book suggests, drilled  
> holes and inserted 1/4"-20 nylon bolts, and I epoxied these to the  
> ends of the secondary tube with the ends of the bolts exposed.   On  
> the top I epoxied a disc of copper, and soldered the end of the  
> secondary winding to that disc.  On the bottom, I soldered the end  
> of the secondary wire to a small plate of copper I epoxied to the  
> outer wall of the tube.
>
> Toroid went on the top - electrical connection made by touching the  
> copper disc on top.  Ground connection to the bottom small plate.

Hi Joe,

Could you go into greater detail on how you performed your secondary  
makeover? Possibly post some pictures if you already have them?

Thanks a lot,
Brandon

On May 27, 2010, at 5:44 PM, Joe Mastroianni <joe@xxxxxxxxxxxxxx> wrote:

> Coil V1.0 ...  in debug mode.  <http://yfrog.com/5d24dj>
>
> Hello All.  My story continues.
>
> I fabricated a circular wooden platform out of 2 23" pine table tops  
> (home depot), mounted the primary, the MMC, and the Terry filter  
> each on different levels.  Then I made a larger platform upon which  
> I mounted the NST, the line filter, and the spark gap assembly.  The  
> spark gap is a static gap consisting of 2 tungsten rods (McMaster  
> Carr) mounted in copper power panel lugs.  The lugs were positioned  
> atop two ceramic standoffs.  I had to use nylon bolts to bolt them  
> to the base, as when I used conductive bolts the capacitance between  
> the two terminals with the wood as dielectric prevented any sparking.
>
> I got a 115V squirrel cage fan (Howard Cyclohm) from Surplus of  
> Nebraska and mounted it also on standoffs, mostly so that it would  
> be the correct height to blow air through the spark gap.
>
> Now it was time to test the gap.  I had bought my NST through eBay.   
> It indeed had a GFI  - but for some reason  the GFI was busted, and  
> it generated nice sparks.  I had made a quick jacob's ladder to  
> verify the operation, but naturally, after making sparks for my  
> spark gap, the GFI woke up and decided to start shutting things down.
>
> This, then, indicated surgery.  I managed to saw the rivets off the  
> NST that were holding on the top.  To my glee, I saw the GFI  
> circuitry was not potted, and I was able to simply yank it out  
> (after removing the circuit breaker switch from the case).   
> Actually, this GFI was more than just a GFI - it had some internal  
> smarts that would assess whether or not the thing was wired  
> correctly, and so had some microprocessor circuitry along with the  
> simple current sense.    After clipping all the wiring, I was able  
> to simply reconnect the primary of the NST.  I put the top back on,  
> replacing the rivets with small 6-32 bolts and nuts.  "Voila," as  
> they say in France and parts of Canada.  My Franceformer was working  
> again.
>
> Dan McCauley's book describes a procedure to measure the resonant  
> frequency of the secondary + toroid, and then use that number to set  
> the MMC+primary combination.  I was able to do that with a signal  
> generator, an oscilloscope, and two LEDs.   Things were moving  
> swimmingly.
>
> I adjusted the Spark Gap according to the notes here on the TCML.   
> Then I set the safety gaps on the Terry filter the same way.  I had  
> built my wooden foundation so the power supply would be separate  
> from the coil itself, but I rested one atop the other for the sake  
> of my first light test, and I wired everything up.
>
> Now - it's time to mention that I had to perform some surgery on my  
> secondary.  The only part of the coil that I did not make by hand  
> (other than the electronic components and the toroid) was the  
> secondary.  I bought that via eBay.  The problem I had with the  
> secondary is that it did not follow the "rules" I had read in Dan's  
> book, and also here on TCML.  That is - one should never have  
> anything inside the core of the secondary.  The person I bought the  
> secondary from suggested wiring both the toroid and the ground  
> through the center of the coil, through holes one has in caps you  
> place on the top and bottom of the secondary tube.
>
> I undid this.  He had drilled holes in the secondary tubing, and  
> inserted the wire ends on the top and bottom.  I pulled these out,  
> plugged the holes with epoxy.  I made plugs for the top and bottom  
> from 1/2" thick sheets of gray PVC as Dan's book suggests, drilled  
> holes and inserted 1/4"-20 nylon bolts, and I epoxied these to the  
> ends of the secondary tube with the ends of the bolts exposed.   On  
> the top I epoxied a disc of copper, and soldered the end of the  
> secondary winding to that disc.  On the bottom, I soldered the end  
> of the secondary wire to a small plate of copper I epoxied to the  
> outer wall of the tube.
>
> Toroid went on the top - electrical connection made by touching the  
> copper disc on top.  Ground connection to the bottom small plate.
>
> I mounted everything on the primary assembly, wired everything, and  
> then connected the RF ground to a rod I pounded in outside in my  
> wife's garden.
>
> Using a variac, I slowly increased the voltage.  Instantly, I saw  
> where little arcs were forming.   I was able to solve most of these  
> by tigthening bolts, resoldering certain connections where I had  
> left rough ends, and ridding myself of inadvertent capacitors formed  
> by having the lug connection to my MMC above the polycarbonate sheet  
> in which the capacitors were mounted, and the eye grommet on the  
> underside, shorted by the bolt that went between them (see  
> picture).  This turned out to be a bad idea.  I put the eye and the  
> lug on the same side of the sheet and those little coronal arcs went  
> away.
>
> But alas - I was (and still am) getting corona break out from turns  
> in the secondary,  and arcs between  turns of the secondary.  I have  
> tried changing the tuning, but this doesn't change things.  I have  
> tried to see if I had some spots of epoxy left over from my  
> modification of the secondary, and I wiped down the secondary with  
> alcohol.    It seems pretty clean.
>
> But when I turn up the variac, I get these breakouts on the  
> secondary.  Changing the tuning eliminates the breakouts and arcs,  
> but I think it does that simply because the tuning is wrecked and  
> currents don't build up in the secondary.  In any case, I never see  
> a corona or an arc from the breakout point I put on the toroid.
>
> Whew.  Thanks if you read along this far, and any advice you could  
> lend would be much appreciated.
>
> Thanks,
>
> Joe
>
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