Capacitive Liquid Sensor Built with Arduino

The goal of the capacitive liquid sensor is to measure the change in capacitance or charge between two metal plates depending on the material between them, making it safe to use with any liquid.

The capacitance measurement is done by measuring the charge and discharge time of capacitors through resistor. The sensor works by charging the capacitor and measuring how long it takes to drain through the resistor. The construction makes one plate connected to Ground while the other is connected to Pin 23. From Pin 22 to 23, a 820KOhm resistor is located.

The LCD used contains 16 through hole pads where some of the pins have to be attached first. For other patented type of LCD, a specialized pin header can be used. Alternatively, wires can be applied to get the connection done as quickly as possible. This requires 16 pieces of wires with simple cut to abut 13mm or 1/2” and be soldered on the board.

The Arduino can be powered enough by the USB port along with the LED backlight. It only needs connecting the Ground and power rails on the breadboard to the Arduino board power out.

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