Ph probr problem

Paul Nicholson replied:

>You can try to limit the pickup to your PH sensor by using a shielded wire
>to the PH amplifier, twisting the pickup lead (if it's twinlead),
>shoortening the lead, and trying a metallic shield over the PH sensor (does
>Vegamite come in cans or bottles?).

Last night I fiddled around a bit and discovered that if I place the probe
near the ballasts there is little or no interference. I presume that it is
the current running through the tubes them selves, therefore this would
continue to happen even if I used magnetic ballasts. 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? Sorry for all the questions. I will try
your current suggestions when I get home tonight. I relly dont want to have
to spend money on buying a sump just to accomadate the Ph probe.

Vegemite comes in jars as a spread for bread and the like. It is extremely
delicous, however it is very strong in taste and should only ever be spread