The gas tank on your car has a fuel-level sending unit that works like a potentiometer. A float moves up and down with the gasoline level, changing the variable resistor setting and producing a voltage proportional to the gas level. A full tank produces 12 V, and an empty tank produces 0 V. Design a circuit using an LM339 that turns on the “Fuel Low” indicator lamp when the voltage level from the sending unit gets below 0.5 V.