This water tank level sensor uses MPX-2010DP silicon pressure sensor to measures liquid level accurately, while at the same time prevents any contact between the transducer and the liquid to be monitored. The non contact sensor is mounted inside a small project case, and screwed directly to the water outlet of the tank.
“Air remains in the 3mm plastic tube, and is pressurized by the water coming in from the tank. The more water in the tank, the more force that is placed on the air in the tube, increasing the pressure which is read by the second component of the sensor, the sensor circuitry”, said kayne richens, the project designer.
The sensor circuitry consists of an instrumentation amplifier to read the pressure sensor, a 1.5V to 5V voltage step up circuit, a PICAXE microcontroller to convert the analog signal from the pressure sensor to a digital reading, and a 433MHz RF transmitter to transmit the water level and battery voltage to a remote base station and computer.
On base station, a 08M PICAXE microcontroller reads the incoming water level and cell voltage from an RF receiver, and transmits the values out over the PICAXE serial download cable for the PC to record. There is also an LED that flashes when data is received.