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Re: [TCML] Racing sparks - question
If you have handled the sec without gloves on there is a strong possibility
that sodium salts from your skin may have been deposited on the wires thus
causing various conduction points along the coil. Some people have very dry
skin so this may not be a problem, while some have more damp skin and there
is a lot of conductive sodium in your sweat.
If racing sparks have occured you now have very small "pinholes" in your
insulation which can lead to continuing problems. If only a few you might
get by, but if there are a lot of them, sometimes so small you can't even
see them, or if they are on the inner side of the wire where you can't see
them, then rewinding is the usual solution.
Best way to properly set coeff. of coupling is to use JAVATC to accurately
calculate the k value. Keep it in the general range of 0.1 to 0.14. I
usually find that 0.15 to 0.2 gives me the longest sparks. You should also
use the "water heater element" method to measure the coeff. of coupling.
You can also small a small elec. heater --- anything that gives you a
primary current limit around 10 Amps will work fine.
All of these issues need to be properly addressed to eliminate this
problem. With most high voltage systems, in which great stress is always
present, once sparking has occured it will continue. You may even have to
rewind the sec coil is this problem continues to plague you.
On Sat, Aug 7, 2010 at 7:43 PM, <otmaskin5@xxxxxxx> wrote:
> Hi coilers. Life's been busy the last few months & not much time for
> coiling, although I still read the pupman postings. Anyway, I did find the
> time to roll out my coil tonight & run it, but I kept running into on an old
> problem I've had in the past. Using a screw or ball bearing for a breakout
> point, my 15/60 coil produces good sparks, and the coil runs well with no
> problems. If I remove the breakout, I still get sparks from the toroiod,
> but eventualy start getting racing sparks. Without the breakout point, the
> coil seems to have no trouble producing sparks from the topload even fairly
> lower variac voltages, but when I increase variac the voltage to the 120 or
> higher I eventually get the racing sparks. I've played around with
> raising the secondary to reduce coupling, but so far, I'm still getting
> racing sparks if I dont use a breakout.
> If it's just a matter of over coupling, I'll have no problem gradually
> raising the secondary to eliminate the problem. However this will be
> somewhat involved as I have to removing the secondary's end cap & adding a
> longer mounting bolt. Before I go much further, I wanted to see if any of
> you guys had other suggestions on what might be causing the racing sparks
> when I don't use a breakout. I'd really like to be able to run the coil
> without using a breakout.
> FYI, I have a 6 X 20.5 toroid and a 3 X 12 toroid underneath it.
> Thanks for any suggestions, Dennis Hopkinton MA
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