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Re: Unexpected Shock From TC

At 01:27 AM 5/5/99 -0500, you wrote:
>
>
>
>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.  
>	More likely, though, is that the secondary can hold a charge, too.  I'm
>not sure if it has to do with the self capacitance of the coil, or the
>varnish on it, or what.  However, I know that most big coils I have seen
>could give quite a zap if you touched the secondary, even several minutes
>after operation.  Usually, the operator would take a grounded wire and
>touching it to the secondary to remedy this.
>
>	Again, just thoughts of mine.
>
>
>
>							Brent

Coils that have thick coat of varnish can store pretty powerful static
charges on the varnish.  Coils can charge this dielectric layer to
extremely high voltage so that there can be an unexpectedly powerful charge
stored on this seemingly benign dielectric surface.  One solution is not to
coat the coil with a thick layer which keeps the windings near the surface
where they will act to ground out the electrostatic charges.  Another (used
by most) is just to realize the static charge is there and prepare one's
self before grabbing it :-))

	Terry