Re: Ph probe problem

> From: Andrew Hamilton <andrewha at tafe_sa.edu.au>
> My current thoughts on
> rectifying the problem is to section the probe of under the hood from the
> lights by using a wall made from plumbers lead. Does this sound feasible? Is
> it necassary to earth the lead? Will the magnetic field pass through the
> glass lids and into the water, therefore going around the lead barrier? Is
> there some way of making something along the lines of an earth leakage
> circuit to drainthe magnetic field? 

The problem is induced voltage caused by an electric field not a static
magnetic field. You can use aluminum foil as an effective shield. Yes,
I believe it should be grounded (connected to earth). Water is a conductor
and if connected to the ground circuit, it will also act as a shield
(although much less effective than metal). I won't go further into
electro-magnetic effects and theory since my attempts to clarify the
difference between electric and magnetic fields may only confuse and I
am not a physicist. ;-)