Electrical hacking (was Re: [Techtalk] [OT] charging USB device without a PC)

[Maria Blackmore]

On Sun, 13 Apr 2003, sara wrote:

> Might be wrong, but isn't it also harmful if you're touching the
> capacitor with one hand, and a piece of metal with the other, or if
> you're wearing non rubber-soled shoes, or are in any way grounded in a
> manner that would allow the electricity to travel through, as opposed to
> down-one-side?

There is only a problem if the circuit is completed.  If you hold one side
of a capacitor in one hand, and grip a metal pipe with the other, there
will be no problem.  This is because the circuit isn't completed and no
current flows.  However, if the other side of the capacitor touches the
pipe too (or part of yourself) then the circuit will be completed, and
life will become briefly unpleasent.  At least until such time as the
capacitor is discharged, or you die, whichever comes first or as
appropriate.

> I would think that it's a bit more than just "one finger on hand A on
> capacitor side A and one finger on hand B on capacitor side B".

Nope, with a capacitor, this is all there is to it,

Electrons are perfect accountants, you never find any go missing, and they
will only flow if there is a completed circuit.

Maria