Re: VanderGraaff safety (fwd)

[brian whatcott <inet@INTELLISYS.NET>]

At 16:26 1/5/99 -0800, Bill wrote:

> With a regulated DC supply and a DVM in series, all clip-leaded to two
> large jeweler's screwdrivers, the resistance between my one hand and the
> other is:  19.9v/1.16mA ~ 800 ohms!! ...
> William J. Beaty

Using a wall wart set to 12 volts  (unregulated - so it floats to 18.5
volts off load) and capable of 300 mA, I attempted to repeat Bill's
striking test:
but my DVM whose minimum reading is 100 microamps, would not register any
value above zero. So I selected a Simpson's d'arsonval movement with fsd=50
microamps.
Using the modest area of the meter terminal screwthread and a battery clip
connected to the wall-wart I read 24 microamps at an applied potential of
17.6 volts from hand to hand.
 This represents (I promise you I did not fudge the data) 7.3E5 ohms.

 I can easily acknowledge that the conductance is (unsurprisingly) a
function of skin area and pressure. And my electrodes were evidently much
smaller than Bill's. Still, the difference is quite striking:
Bill: 17 kilohms: Brian 730 kilohms.

I would be most interested in any other determinations of skin resistance.

Brian
brian whatcott <inet@intellisys.net>
Altus OK