Quote Originally Posted by mackrackit View Post
I think you need another solution. The long wire will have capacitance of it's own.
Yes, I thought of that. But this shouldnt be a problem, I can calibrate the unit once to compensate for the cable capacitance.

Its actually a string of 10 capacitors in series immersed in a water tank. The water shunts out each capacitor as the level rises.

I did have an earlier version with the resistance being a variable, using the ADC, but this tends to get corroded within a few weeks.

The capacitive version seems to work well, but for this problem; and seems to have no corrosion issues either. Would be a pity to have to abandon this design.

Any other ideas?

Anand