Re: Capacitive water level sensor


Joerg wrote:
Electric dabbler wrote:


Is it feasible to sense water level in a plastic container with capacitive
sensors on the OUTSIDE of the container? The container concerned will be a
heavy gague plastic water storage vessel - perhaps 2 - 3mm thick walls.


Yes, feasible.


I'm thinking of using some strips of 1" copper tape glued to the outside
and attempting to sense the change in capacitance caused by the presence of
water at that level in the container. I suspect the problem here is tha the
change would be too small to reliably detect?


You'd have to shield and compensate against outside influences (hand,
bird landing on container, dirt, dust, rain etc.).


Alternatively I could immerse just one long stainless steel rod in the
container as one capacitor 'plate' and using single copper strips on the
outside at various levels. Here could energise the external electrodes
squentially and measure what comes back on the stainless steel rod relying
on the conductivity of the water to form the other 'plate'


You can, but it should be possible without. The rod might corrode even
if stainless, or at least gunk up.



I need to sense multiple levels and drilling holes in the container is not
really an option.

I'm not after a commercial solution, just a quick and dirty DIY approach.


For stuff like this I'd use sound, little piezos fastened at the desired
levels.

--
Regards, Joerg

http://www.analogconsultants.com

I am interested in the same thing and found a dev baord and chip at
http://www.qprox.com/products/continuous_sensing.php

I never ordered the unit and the website has changed A LOT. In any
case they had several designs for exactly what you want to do. Soem
used a piece of PVC pipe immersed in the tank as the sensor.

Bill

.

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