Re: Electrometer design (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Sat, 10 Jul 2004 08:31:25 +0930
From: Matthew Smith <matt@xxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Electrometer design (fwd)

Charles Brush wrote:
> The design is incredibly simple.  Basically you have a little NE2
> lamp in parallel with a capacitor with one side attached to ground
> and the other to an elevated and sharply pointed rod.  As the local
> field increases current will flow through the circuit causing the cap
> to charge and periodically discharge through the NE2 causing it to
> blink.  The faster it blinks the stronger the field overhead.  I
> tried this a few summers ago but I can't remember the cap value I
> used (anyone have suggestions?).

This design (or one like it) is described in Iannini's "Building your own
working fiberoptic infrared and laser space-age projects"  (the book with the
long-winded name).  The capacitor value is given as 1nF @ 1kV.  Fig 14-12 on
page 238 in my copy.

This uses a metal can instead of a pointed rod as a charge collector.  This sits
on a plastic aerosol cap to insulate the can from ground.  NE2 shows through a
hole in the cap.

Cheers

M

-- 
Matthew Smith
Kadina Business Consultancy
South Australia