Abstract In this article, the design of a low-cost educational liquid-level sensor circuit is described. The sensor is of capacitive type and is in the form of a parallel plate capacitor made up of two aluminium foil papers stuck on opposite sides of the container whose liquid level is to be measured. The sensor works on the principle that its capacitance changes with the level of liquid in the container as a result of the change in permittivity between the plates.Thus, by calculating the capacitor value, one can calculate the level of the liquid in the ...