RE: secondary question

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

While there is indeed some capacitance between secondary windings, don't
forget that there is also a substantial piece of copper, the secondary
winding, connecting all of these "plates" together.  After the coil is
turned off, the DC time constant of the secondary resistance and the
inter-turn capacitance is a fraction of a nanosecond.  No residual
charge would be left after your finger left the off switch.

Realize too that after the unit is turned off, the secondary and top
load are at a ground potential by virtue of its base connection.
Grounding the top load with a grounded probe accomplishes nothing.

The cause of the post-turn-off zappings is from the rectification that
occurs from dissimilar-shaped electrodes generating corona.  The RF
corona coming off the secondary windings generates more current in one
direction than the other.  This deposits a net DC (static) charge on the
surface of the various insulating surfaces on the secondary, though the
actual charged medium (PVC, polyurethane, and/or wire enamel) is
unclear.

Regards, Gary Lau
MA, USA

>>Original poster: "Michael Rhodes by way of Terry Fritz
<twftesla-at-qwest-dot-net>" >><rhodes-at-fnrf.science.cmu.ac.th>
>>
>>Since the TC secondary looks and behaves like a distributed
>>capacitor, each pair of adjacent wires is a mini cap and the
>>charging and storage of the charge of these mini caps depend
>>on the dielectric constant (this would be the wire insulation
>>and air gap between the wires and also dependent upon the
>>resistivity of the coil form), you would have a gradient charge
>>on the coil.  The higher the resistivity of the coil form the
>>less drainage of the capacitance and thus the longer it will
>>maintain a charge. This would explain why the higher up
>>you go the more intense the shock and why some coil forms
>>are less susceptible to the effect. Looks something like this:
>>
>>GND-----|-----|(------|-----|(-------|----|(------|--0
>>                |----res-----|----res------|----res----|
>>
>>where 'res' is the coil form resistance/interwinding leakage
>>and --|(-- capacitance of each winding pair and '0' is the top
>>load.  So, if you have a 1000 turn secondary you would
>>have 500 mini capacitors in series.
>>		
>>When you turn off the power at a position where the top load
>>has not discharged, some energy has to be still stored in the coil.
>>One way of verifying this is to use a grounding rod (just a plastic
>>rod with a ground wire on the end) and short the top load to this
>>ground.  We use these on all our high voltage top terminals
>>and toroids and leave it connected as long as we are working
>>on the systems.  To preclude that it is not a static charge built
>>up in your body, ground yourself first to the rod to discharge
>>the static.
>>
>>Just my theory on this phenomena, mileage may vary:-)
>>
>>--Michael



 > << Hi Everyone,
 >
 >       This weekend I just finished my first coil (6") and got results
of 12"
 >  which was about what I expected due to no tuning, it's incomplete
power
 >  supply and bad topload.  Well anyways I was running it at 30 second
 >  intervals making changes each time and after the 3rd run I noticed
the
 >  secondary was a bit crooked.  So I discharged the caps and reached
out and
 >  put my hands on the seconday to lift it to look at it and I got a
 >  surprizing shock.  I touched it a few more times and got a few more
jolts
 >  and found the higher up I got the more powerful they were.  After
about
 >  five jolts they died but after I powered the coil they came back.  I
had
 >  never heard of this on any pages before (although I may be wrong) so
I was
 >  surprized.  They weren't terribly powerful but they did fell a lot
like
 >  static shocks from a Van De Graff generator, but I'm not sure how my
coil
 >  could produce much static.  The only other guess I can make is that
since
 >  the secondary exhibits isotropic (self) capacit!
 >  an!
 >  ce to the ground, it could retain a charge after the power is turned
off.
 >  Has anyone else encountered this?  Does anyone know if these shocks
are
 >  safe, because after writing this I feel like shocking myself maybe
wasn't
 >  the smartest thing I could of done.
 >
 >        An admirer of coilers everywhere,
 >       -Will Daniels      >>
 >
 >
 >