RE: newbie question - spark gap and toroid

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "ho \[shu\] huang" <shuhuang-at-singnet-dot-com.sg> 

Hi Rich,

thanks for the tip. I may bust out the file and round the ends. But in the 
long run, I'll probably replace the aluminium rods with copper. I ran my 
coil at near full-voltage and stuff started to heat up. Not to the point of 
failure, but the spark gap was now warm to the touch. I also increased the 
spark gap length, not knowing what exactly I was doing, and blew a 
capacitor. Actually, that's a funny story.

I was sort of fiddling arnd with the spark gap, widening a little bit at a 
time till it reached a point when the safety gap started sparking. Soon 
after, one of the resistors started sparking and actually caught fire. I 
cut the power and the small fire died. I replaced the resistor but sparks 
arced across it. I figured that the capacitor the resistor was across had 
blown and the circuit had shorted. True enough, the side of that capacitor 
had cracked. I guess the moral of the story is to not push your coil too 
far! Thank god that's all that blew, and I had spare capacitors lying arnd.

I've pretty much optimised my coil now. I think all that's really left to 
be done is to run it with a good ground. I get sparks which go up to 12-15" 
now, and are certainly a lot brighter. My prof thinks that's good enough 
for his purposes, and would rather have the coil perform reliably well 
within its limits.

I took this photo today, with a Maltese Cross. I think it's pretty cool as 
it looks like a UFO zapping something haha. 
http://web.singnet-dot-com.sg/~shuhuang/tesla_maltese_cross.jpg Sorry for the 
poor quality of the shot - my digital camera's incredibly bad with night shots.

Shu



At 08:14 AM 11/2/2004 -0700, you wrote:

>Original poster: "Rich" <rdjmgmt-at-socket-dot-net>
>I have a 30ma 15kv coil also and the spark gap works better with a fan ,
>my first gap was with tungsten rods , then went to a RQ style with TI
>tubes , they sparked on the end until I polished all the burrs off the
>ends and the polishing makes sure the dia of the end of the tube is
>smaller so there is not a sharp edge or point for the spark to jump to.
>Rich
>
>
>Original poster: "ho \[shu\] huang" <shuhuang-at-singnet-dot-com.sg>
>
>Hey!
>
>I've got my tesla coil to work but I've got a couple of quick questions
>for
>you pros out there: -
>
>1. My SG spark gap's made from aluminium curtain rail, not copper pipe.
>The
>rail is flat, so it's easier to mount. Does it matter? My coil works,
>but
>I'm not sure if aluminium hinders performance in any way.
>
>2. Does it matter that air isn't blown directly at the sparks? Do the
>sparks require a lot of air to be "quenched", or will a bit of moving
>air
>be enough? In other words, is more wind better?
>
>My spark gap (pic here:
>http://web.singnet-dot-com.sg/~shuhuang/spark_gap3.jpg
>) sparks at the ends of the rails, which is sort of shielded by the 10mm
>
>thick plastic support. I can easily reconfigure it so that the sparks
>get
>most of the breeze from the fan, but I'm wondering if it's worth the
>effort. The fans blow, rather than suck, BTW.
>
>3. I used 2 aluminium wok covers joined together
>(http://web.singnet-dot-com.sg/~shuhuang/tesla_coil_lab.jpg ), ~210mm wide
>and
>320mm in diameter, as a toroid but I suspect a traditioanl toroid might
>work better. Believe it or not, I'm actually having a hard time flexible
>
>drainage pipe. It's apparently not used very often any more...where I
>live
>(SIngapore) anyway. I came across the pool float toroid design on a
>webpage, and I've found one on sale cheap. It's 23" in diameter and 8"
>thick. Is that too big a toroid for my 15kV 30mA, 90mm 900 turns AWG 24
>wire secondary coil, set up?
>
>thanks!
>
>Shu
>
>