This is a non-contact liquid level sensor can detect the liquid height in the closed container, overcoming the problem of thick container walls. Its working principle is to use the water sensing capacitor to detect whether liquid is present. In the absence of liquid near the sensor, there will be a presence of distributed capacitance, and therefore there are some certain static capacitance to ground on the sensor. If the liquid is close to the sensor, the final capacitance of the sensor grows bigger. Then the changeable capacitance will be converted into some signals variation. Then, a certain algorithm will detect and determine how much this variation is. When a certain threshold value is exceeded, the liquid level is considered to reach the induction point. Equipped with a XH2.54 conversion board, the signals can be controlled by sliding switch. Slide to SET end, the level is high; on the contrary, the level is low. It can be interfaced with Arduino and other controllers, therefo