Electrodes construct capacitors, always made from metal, which is its building blocks. Both the electrodes are essentially electrically insulated from each other. They are most important in a capacitor because they store the energy in space between them when a potential difference is applied across the circuit.
The capacitance of a capacitor is increased many folds when a non-conducting material is placed between both of its electrodes. This is referred to as a dielectric material.
Liquid as Dielectric between Capacitor Electrodes
When a liquid is introduced as a dielectric material between the capacitor plates or electrodes, the capacitance of that capacitor increases. As the capacitance changes, the liquid level can be determined.
The variation in the circuit potential is proportional to the changes in the capacitance of the capacitor. The changes are detected by connecting the capacitor to an alternative current that measures circuit. The more is the dielectric material between the electrodes, more energy or capacitance changes will occur.
The zero and full tank measurements are first taken first for calibrating the sensor. The sensor between these two values will then measure the capacitance values.
Capacitance Level Sensors for Liquids
With a capacitance level sensor the capacitance changes when the sensor tube is dipped in water or the water around the tube rises to a different level. As the capacitance tube is dipped in the water, the capacitance increases. The increase in capacitance is measured by the electronics at the top of the sensor.
The output frequency goes into the interface device which is proportional to the fluid in the tank. Alternately, you can also work with the DQ 1008 which can give you a USB output, wireless output, or an analog voltage output. So, it is very flexible and useful for whatever application you are looking for.
For instance, you are working with a USB output device. So, the sensor output is being converted by the interface into USB output. The computer USB port is providing the entire path to power the sensor.
Level View Software
On your computer or laptop, you will have the level view software that takes the information sent by the sensor and displays it on the computer screen in actual numbers, such as, 100mL of liquid level. It can also plot this data, as well as chart this data. Furthermore, the software allows you to set alarm limits. So, if the level in the tank falls below a certain level, then it can send a text, message, or an email message to an appropriate person.
So, this is a digital level sensor for liquids based on the capacitance principle. The capacitance provides frequency, voltage, or a USB output. You can also make it a wireless output base on the wireless interface options and then use it on a PC or any other computing device which can work with a USB output device or may be a wireless output. Essentially, this is an elegant 21st century solution for measuring levels.