AVR-Chat

On Tue, Jan 13, 2009 at 8:43 PM, Enki <enkitec@gmail.com> wrote:
>
>        I need to measure the liquid level inside a transparent plastic
> bottle. I need to know when the liquid is below half bottle height and
> when the bottle is almost empty. Just two steps.
>        The plastic bottle measures 12cm high x 8cm x 3cm.
>        I'm not allowed to insert any probe in the bottle.
>        There are four bottles side by side.

Is the liquid transparent, opaque, or uncontrolled?
If transparent, you can use the lensing effect. Shine a light source
through a bottle and observe what happens.
If opaque, then the liquid would block a beam.