Capacitive level sensing: http://www.ti.com/lit/ug/tidu736a/tidu736a.pdf

 

Another capacitive level gauge: http://www.rst-engr.com/kitplanes/
Look at Jun.,Jul, and Aug. 2000

Ken

 

- MCU for data processing, most time it will be in sleep mode, will wake up once every two days or even less

capacitive sensing is the way to go then. I use a piece of pcb, with two traces on them and coated with polyurethane to insulate them the liquid. Incredibly flexible and rust resistant. interfacing with a mcu is easy, especially if you have a capacitive sensing unit or ctmu.

 

Have seen this before yes. But I was only able to find high voltage sollutions. Maybe if you have some specific information (operating voltage and current) or actual product link. I'm interested in 3,6 V sollutions (low power).

http://www.gemssensors.com/Level/Multi-Point-Level-Switches/Float/Small-Size/LS-300-Series

Float on a 3 level model. The sensor takes no power, its only a contact closure/open for the position of the float that can be connected to a input port on a typical controller using a current loop, resistor pull-up/down or another simple method to detect the fluid level.

 

Capacitive level sensing: http://www.ti.com/lit/ug/tidu736a/tidu736a.pdf

Have seen this before. It's a nice sollution, but I'm planning on putting the sensor in the water and in this case I cannot done that. Maybe I could make similar sensor. I will take a note. Thank you for remiding me.

Another capacitive level gauge: http://www.rst-engr.com/kitplanes/
Look at Jun.,Jul, and Aug. 2000

Ken

Thanks, this seems pretty interesting. Will read it.

capacitive sensing is the way to go then. I use a piece of pcb, with two traces on them and coated with polyurethane to insulate them the liquid. Incredibly flexible and rust resistant. interfacing with a mcu is easy, especially if you have a capacitive sensing unit or ctmu.

Yes, I am lookin more and more into that direction. This is exacly what I need. I will try that kind of sensor, if i don't find some other suitable sollution. Thank you.

http://www.gemssensors.com/Level/Multi-Point-Level-Switches/Float/Small-Size/LS-300-Series

Float on a 3 level model. The sensor takes no power, its only a contact closure/open for the position of the float that can be connected to a input port on a typical controller using a current loop, resistor pull-up/down or another simple method to detect the fluid level.

Thank you for posting. Will look at it. This seems like a way to go.

Well you guys amazed me. You have all been very helpful. Now I have much things to consider and take a look. Will probably make multiple sollutions and I will see which one will be the most suitable for project. Again thank you all again. Still if someone got a new idea, I'm still open to suggestions.