A liquid level assembly for controlling liquid level has a switching mechanism responsive to the liquid head to activate a pump. The method includes measuring output speed with the output speed sensor and comparing the measured output speed to an output speed threshold. Ferroelectric stress is applied to the cells either before or after the cells are written to by repeatedly applying a voltage to the cells corresponding to a logic state opposite that of the written logic state. Consequently, the voltage switch circuit may be produced by a logic circuit manufacturing process. The separator layer includes a porous anodized metal oxide layer containing substantially straight and parallel nanometer scale through-pores haying a diameter of less than 100 nm.