On 2006-08-03, Z wrote:
jasen wrote in :

Oops, the ADC input tolerance is -0.3V, not -0.5. I'll look for germanium
diodes though! -0.2V would work.

The output impedence is somewhere around 500K-1Meg, which is why I'm using
a 10 teraohm input impedenace op-amp. The sensor ground is simple connected
to circuit ground.

could you connect the PH sensor ground to a voltage divider instead ?

Bye.
Jasen