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Re: Unexpected Shock From TC
Hiya Mike (yup I´m still alive),
>Original Poster: Hollmike-at-aol-dot-com
>
>In a message dated 5/6/99 5:00:58 AM Mountain Daylight Time, tesla-at-pupman-dot-com
>writes:
>
>> >
>> >To Bill Langston, and all coilers:
>> >
>> > I noticed in your post that you (Bill) wrote that you got a shock by
>> >touching the TC long after it was turned off. I know of two reasons why
>> >this might happens, and how to fix each of them.
>> > One cause is that the tank capacitor can hold quite a charge after the
>> >coil is shut off. It usually bleeds off through the circuit after a few
>> >seconds, maximum. However, according to Terry Fritz, if some connection
>> >in the circuit is disconnected, this bleeding off may not happen. Ask
>> >around for ideas about bleeder resistors across the tank capacitor, and
>> >other ways to fix this.
>
>
> I cannot see how one would get a shock from touching the secondary with
>the primary cap having a residual charge. Unless the spark gap is firing,
>there is no energy transfer to the secondary. You could get a fairly nasty
>shock touching anything in the primary system if the cap has a charge on it.
> The likely cause is that the secondary(self capacitance) retains a
>charge. My 8 inch coil has a very thin coating of insulating varnish(applied
>with a spray can) and still retains a charge after shutting down. This
>varnish has a dielectric strength of 2100v/mil so even a thin coating can can
>hold a fairly good charge.
Total agreement. A "held" charge can only be DC and in the case of a TC, the
secondary is "disconnected" from the primary circuit, once the gap quits
firing.
(of course there can be a residual charge on the caps, but this won´t act upon
the secondary). So the only charge a coil can hold, is a static charge, which
would have to result from a DC field being present, I think (which once again
leads to the question if there are DC fields around coils [;o]).
Coiler greets from germany,
Reinhard