RE: Problems with First Tesla Coil

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

Original poster: "Ted Rosenberg by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Ted.Rosenberg-at-radioshack-dot-com>

Dan: Just a suggestion...
When I first setup my coil after a major rebuild, I too got "nothing" at
first power up using the variac.
Then I realized it was *way* out of tune. So I laid a three foot strip of
right angle aluminum across the toroid. sure enough, in total darkness, I
saw 3-4" streamer clusters from both ends of the strip and no where else.
I made major tuning changes and finally found the right place. Suddenly I
was up to 2 foot streamers. Later, the toroid, which was far too small, was
swapped for one much larger which resulted in even better performance. I
went from 4x16 to 6x21. Now I am about to jump to 8x24.

Check your wiring and the usual connections. Tighten all carefully. Then try
this method and note if you get any breakout at all.

The MMC seems to have the right value. With a 120bps gap you need an LTR and
for the 15/60 (mine too) .028 is about right.

But the fact that you report blowing caps means that there is something else
not right and I'd check the SRSG for openers.

And
Safety First

Ted

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Monday, August 26, 2002 10:38 PM
To: tesla-at-pupman-dot-com
Subject: Problems with First Tesla Coil


Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<dhmccauley-at-spacecatlighting-dot-com>

Hello,

I am having some problems with my first conventional tesla coil.  I've been
trying to tune the thing all night, but no success.  Only a few blown MMC
capacitors.  Here are my specifications:


15kV/60mA NST
Synchronous Rotary Spark Gap 120BPS  (with safety gap)
.0275uF, 28kV MMC (LTR type)
13 Turn Primary

Here are my questions - hope their not too many . . .

1.  From my calculations, if I was using a 0.0106uF capacitor, my primary
wouldn't be able to tune this as it calculates to about the 15 turn. (Mine
is only 13 turns)  However, if I make this calculation
with my LTR capacitor (.0275uF), then the primary should be tapped
approximately 7-8 turns.  Does this sound right, or when using a LTR sized
cap with a SRSG do I need to do something else in my calculations???

2.  I've never tuned a tesla coil before.  Tonite I was just going around to
every turn, inching up my variac to about 25%, and monitoring current or
hoping to see a little streamer or something.  But nothing.  For a typical
primary this size, how much tapping range is there to actually have the
think work a little.  Is it very narrow, or if i'm within a half a turn i'll
get some output???

3.  When I actually do hit resonance, at what percentage output voltage
should i expect to see some type of streamers begin???

4.  Can the quality of the RF ground be the difference between output and no
output???  I know some people on this list claim to get output even when the
RF ground is left floating??

5.  Anything else that i might be missing???  The SRSG is running fine and
sounds like its properly running.  It is synchronized with the 60Hz and
tuned correctly.

Tomorrow I will use a smaller toroid to see if I indeed have a primary with
too few turns.

Thanks for all the help.  I'm about scratching my head right now.

Dan