I am doing a project on water level controllers. I am primarily designing a capacitance sensor for this purpose. I am looking for more information regarding the sensor and also the signal conditioning part. Looking forward to responses.
thanx a lot,
Tanya.

 

Depending on the accuracy needed this could range from a strip of metallic tape on the outside of a plastic container to a very sophisticated collection of electrodes. I might begin with a
CMOS multivabrator oscillator that varies frequency with the capacitance of an insulated rod to the water in a grounded container. The frequency can be counted with either an
inexpensive counter or a PLC module. Since the signal is digital, no conditioning should be neccesary and any required averaging/filtering can be done in the digital domain.

Regards

cww

 

We tried using capacitance sensor for level control and they worked fine as long as the liquid is always the same and the dielectric properties are stable.....clean water OK...forget waste water....its composition was changing all the time! The vessel also has to be kept clean....we were sensing through the sides of a plastic vessel and got false readings if there was even a hint of buildup on the inner surfaces.
Good luck!

Gerald Beaudoin

 

May I know why you have selected capacitance type? I would recommend a float type sensor which is more suitable for sensing level of water.

Regards,
[email protected]

 

Hi.. I have a project to detect water level. And i am interesting with capasitive method. But i don't know the sensor type that i can use for my project. Can you give me an explain about the detail type sensor? and also the circuit for using that sensor. Thanks for your attention.

 

Basically, when you work with capacitive-type sensors, you need to use oscillators with a certain frequency. The number of beats or frequency will determine the characteristics of the capacitive-type sensor. If the signal is small, it is recommended to use a capacitor bridge, which is similar to a resistor bridge except that the resistors are replaced by capacitors. 4 components in total for the bridge. Search for basic sensor books, there should be a simplified circuits.