PURPOSE: To simplify the constitution of the whole of a measuring instrument, by using a load circuit, which consists of a water level-concentration probe and an underwater electrode and includes a pair of electrode, to make the constitution for detection of water level and the constitution for detection of concentration into one body.
CONSTITUTION: An output signal V is raised gradually according as the concentration is increased; and when the concentration of a liquid reaches an upper limit concentration, the output signal V exceeds an upper limit concentration reference voltage E2, and the output signal of a comparator 11b is inverted from "0" to "1", and an upper limit concentration signal S2 is outputted. After the concentration reaches the upper limit concentration, the operation is interrupted temporarily to discharge water; and when the water level falls in accordance with this water discharge so that a tip part 9' of the electrode is separated from the liquid surface, the output signal V falls rapidly to become lower than a water level reference voltage E1, and therefore, the output signal of a comparator 10b is inverted from "1" to "0", and a fall signal S1 is outputted.
TANIGUCHI SHIN
FUJITA TADAO
