Re: How do you get the guts (or stupidity) to draw a spark

Subject:      Re: How do you get the guts (or stupidity) to draw a spark
       Date:  Tue, 10 Jun 1997 08:06:49 +1200
       From:  "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
Organization: Wellington Polytechnic, NZ
         To:  tesla-at-pupman-dot-com

Hello Rod, all,

>   From:   Rodney Graham Davies <Rodney.Davies-at-anu.edu.au>
>     To:  Tesla List <tesla-at-pupman-dot-com>
> Hi Shawn,
> On Sat, 7 Jun 1997, Tesla List wrote:
> > Subject:  How do you get the guts (or stupidity) to draw a spark ?
> >   Date:   Sat, 07 Jun 1997 09:35:33 -0500
> >   From:   Shawn Collins <rubidium-at-worldnet.att-dot-net>
> >     To:   tesla-at-pupman-dot-com
> > 
> > 
> > I have seen many pictures on various pages of people drawing sparks to
> > metal
> > objects they are holding on to. At what frequency of operation is this
> > safe,
> > and how  did you ever get up the guts to try it ? I know the primary
> > side
> > can kill, but according to skin effect formula (which I can't find right
> > now) at 170kHz the current is only .06" deep. 
> To be safe, I'd suggest frequencies atleast 250KHz and above.
> Anything below that and you're likely to _really_ feel the RF.
> Anyone else tried it at < 250KHz?
> However, I once tried an experiement holding onto a neon tube where the 
> coil arced to one of the wired ends, but I was only in contact with the 
> glass tube, not the metal bits...but I did feel the energy passing over 
> my hands....I think the frequency, from memory, was around 280Khz.

Skin effect takes place progressively as frequency increases. It is 
not a sudden thing. I have drawn arcs from a coil running <100kHz. In 
principle you should be fine even at 50kHz. The jolts you can get are 
mainly a result of spark gap modulation due to misfires and 
differences in firing voltages each fire. The output from a 
disruptive coil is not continuous RF so you can't expect no jolts at 
all IMO. Also, you can get electrostatic effects as you move in and 
out of strike range. The worst jolts I've received have been at the 
edge of attached streamer length.