On Thu, 13 Apr 2006, Tony Smith wrote:

> The tube can be open ended, no need to seal it.  I thought it might not
> work, but can't think of a reason.  The capacitance would read the same.
> For the tank, I put the tube on the outside because it was easier, and
> well, it never really occured to me to put it inside.
>
> Hmmm, motorcycle fuel gauge...
>
> I was originally going to put a small magnet on a float inside the tube,
> and have a few reed switches outside.  That would work for a pond level
> indicator (reed switches are easier to deal with than hall effects), but
> you need to figure out how to stop the magnet spinning.

If you put a magnet float in the water and a metal wire outside the 
magnet will be drawn near the metal wire. Add two reed switches near the 
wire and it's done. The magnet float need to be attached to anything, it 
can be a plastic flower or orb or whatnot.

Peter
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