Re: Magnitude of feet-scuffing voltage?

[brian whatcott <inet@INTELLISYS.NET>]

At 07:58 1/22/99 -0800, you wrote:
> ...  I want to display the NUMERIC potential difference,
> like "2.45 kilovolts"
>
> I'm looking for an off-the-shelf electrostatic voltmeter which will not be
> harmed by contact with a highly-electrifiec human who has been scuffing
> their feet on the rug.
...
> William J. Beaty

I am probably being needlessly didactic to mention that the leaf
electroscope was intended to be qualitative, but in some refined versions
the leaf electrometer was  capable of quantitative indications.

 A robust development of Kelvin's quadrant electrometer has been used in
recent times for EHT measurements. This movement looks very like a low
capacitance
variable capacitor, whose low friction rotor is attached to a spring biassed
pointer.

 One is tempted to propose a DVM chip because of their  exceptionally high
input impedance around 10^10 ohms. But the nature of the conversion makes
fleeting signals difficult to register. And a potential divider of 10^10
ohms and 10^6 ohms is not on everyone's shelf. ( Some ingenuity is needed
to fashion something of this kind from a slightly conductive plastic film
or tile...)
 I recall the frustrations of measuring the geoelectric gradient of abt.
120 volts/meter.
 One might consider an insulated gate field effect transistor ( IGFET) with
its
gate driven by such a divider, mounted judiciously on expanded polystyrene
blocks for its exceptionally high bulk resistance (which material is quite
capable of blowing most semiconductors from frictional electric effects).
This igfet component is to be found at the shack.

Perhaps the simplest approach would be an (informal) capacitative divider
formed by discharging ones body charge into a high quality mica or
polyester capacitor. This source might then be read on a DVM.

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