On Tue, 23 Mar 2010, yamanoor sairam wrote:

> You are right about the DC voltage oscillating around the mean value. I 
> am yet to gain access to an oscilloscope. I checked the output of my 
> opamp using a multimeter. The opamp remained at 3.3V when I removed the 
> probe out of water instead of increasing to 4.139V. It took a long time 
> before increasing to the desired value. How am I supposed to prevent 
> amplification of all noises at this stage?

This would be easy in software. You know what to expect when the probe is 
in the solution (how the output of the probe should vary over time) and 
you know how the probe IS behaving when it is taken out of the solution 
(you are getting random noise). So write a bit of code that can tell the 
difference and only display a reading when this "detector" code tells you 
the probe is probably in the solution. Otherwise you could just display 
"???" in place of the reading.

Just think about how you would tell the difference between random and 
non random readings.

Regards
Sergio Masci
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