RE: Latest coil
At 01:00 PM 09/05/1999 -0600, Tesla List wrote:
Hi Gary, all,
I've been using just one .01 mfd cap on my coil for a while
doing experiments. I added the second one into the circuit
last night to get .02 mfd and got racing sparks right off the bat.
Actually, the sparks want to travel straight down to the base
of the secondary.
Since I last ran both of the caps together, I have adjusted the
secondary coupling. It is fine with one cap but with both I think
it's just too much. With two caps, there's a lot more corona
coming off the topload
Do the racing sparks happen the entire run, or do you
notice it at a few seconds into power-up? Mine were the
entire (brief) run.
>Original Poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com>
>Hi Alan. All,
>I don't yet have any answers to your racing sparks problem, but if misery
>loves company, perhaps I can offer you that. I'm in the process of
>converting from my static gap to a sync RSG. I had been getting nice 60"
>arcs from my 4 1/4" secondary, power by a 15/60 NST and a .02uF cap. I
>upped my cap to .03uF so as not to over-volt it, and I too am now seeing the
>racing sparks (who coined that name anyway?), and also have a burnt spot at
>the base of the secondary to mend. And I tried raising the secondary, still
>got the sparks.
>Right now I'm waiting for a HV probe that I ordered so I can scope my cap
>charging and phase, perhaps that will show up something. I'll let you know
>if it does.
>Regards, Gary Lau
>Waltham, MA USA
>>Original Poster: ajones-at-pointlink-dot-net
>>Hello everyone. I thought I would post a little about my latest coil.
>>The primary is flat with 3/8" tubing with slots in the form to allow
>>tapping from below. The secondary is an upside down polypropylene
>>trash can that measures 14" diameter on the bottom and 13" diameter on
>>the top and wound with 18gauge magnet wire for 24-1/4" winding length.
>>Two toroids are being used, a corrugated drain pipe wrapped with tin
>>foil that measures 4"x33", and two flexible ducts taped end to end for
>>7"x 40". I am using two of the H&R transformers that are wired
>>anti-parallel for 10kV 300ma. Six sets of polypropylene caps, .013uF
>>each for .078uF or so total and a sync-gap. This isn't quite resonant
>>yet, but will soon be larger than resonant.
>>The first run was just to see that everything worked. There were
>>serious racing sparks and as I found out, several spots had burnt.
>>Some turns had to be removed on the bottom and the other spots had the
>>burnt insulation scraped off and were coated with model paint. Trying
>>again the next night, one of the repaired spots burnt again and three
>>turns had to be removed. But there was a ground strike before shutting
>>down that I later measured at 80". Or 3.2 times the winding length.
>>Pretty decent, but will have to get better :-)
>>I setup again tonight with the newly repaired secondary, freshly
>>soldered and re-painted. More racing sparks and some that jumped
>>straight down to the primary from the lower toroid. Since I have never
>>had these kinds of problems, I didn't really know what to do. I have
>>only run with crappy capacitors before that wouldn't let the power out
>>to the coil and these polypropylene caps are working great. I tried
>>raising the secondary some more to reduce the coupling. It was now
>>1-1/2" above the primary, but still had the racing sparks. The only
>>other thing I could think of was to lower the toroids some. Now the
>>racing sparks have been eliminated. But the spark length dropped,
>>probably from the reduced coupling. I'll try increasing the coupling
>>in a few days and see if the spark length comes back up.
>>So, any comments or suggestions? All welcomed.