AVR-Chat

I have used capacitive sensing successfully on a 4' high
fiberglass tank, measuring the height of the water inside
to within and inch.  I used only one metal plate; the water
inside was a good enough ground plate.

Enki 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.
>
> I was thinking on metal plates mounted on each side of each bottle
> and using the capacitance method.
>
> Or a B&W video camera and some processing. I could generate four
> sample windows on each video line and integrate the samples. The four
> integrated signals would represent the liquid level on each bottle.
> An ATMEGA48 would do the level measurement with four ADCs.
>
> Comments, please.
>
> Thanks,
> Mark Jordan
>
>