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Re: Coil Problems

Josh writes....

> 1.  Arcing between 2 spots on the secondary.  I assume this is
> electrical breakdown, and that some more coats of polyurethane will cure
> this?  Also, I noticed that this did not occur when streamers went to
> the discharge terminal, but when terminal was too far away, it happened.
> I've gotten streamers at about 7", however coil is not yet tuned, and
> voltage has never gone above 85 volts (see why next problem).

Firstly, get the coil in tune (most important). 7" suggests it might 
be a long way off the mark. Secondly, how many coats are covering it 
already? Thirdly, flashovers like this can occur if the coils are 
coupled too tightly. I am mystified about your 85 Volts. Is this the
AC voltage you are feeding to your transformer?

> 3.  This is the thing that concerns me.  After operation of the coil, I
> noticed dust build-up (this should have been a clue) on the secondary.
> (capacitor had been discharged).  I went to brush it off, and received a
> shock (presumably electro-static).  From past experiences, I'd estimate
> about 80 volts.  Secondary was grounded at all times.  I probably had 1
> or 2 mins total operation tonight, cut it off because didn't want to
> harm coil from electrical breakdown.  I'm worried that when the coil is
> run for longer, this charge could build up above 80V, and become a
> bigger problem.  Any comments on this?

The static voltages left on the insulation are measured in kiloVolts
if not tens of kV. As with lightning, the moment you get close enough
to cause a discharge to start, charge redistribution on the insulation
will cause a much larger area of the insulation to join in. You can
observe multiple streamers in the dark. I'd advise using a grounded 
rod to attract these discharges. They can be quite large and painful.

Malcolm