Abstract: Only one pressure sensor is employed in a compact measuring apparatus for measuring both depths of water and altitude. A pressure-data generator generates pressure data corresponding to a pressure applied to the single pressure sensor. A water-depth data converter converts this pressure data into water-depth data. An altitude-data converter converts this pressure data into altitude data. The water-depth data and the altitude data are visually displayed on the compact measuring apparatus.

Abstract: In a voltage selector circuit, a plurality of supply voltages are respectively supplied to a plurality of switching elements formed of MOS transistors. The plurality of switching elements are turned on and off according to the voltage levels of input signals supplied thereto, and a voltage waveform signal corresponding to one selected among the supply voltages is taken out from a common output terminal. The substrate electrode of a specified one of the switching elements is supplied with a corresponding supply voltage as the substrate voltage in response to a voltage change of the voltage waveform signal taken out selectively, thereby reducing power loss in the circuit.

Abstract: A power supply system for an electronic device having a battery power source, a logic circuit, a voltage dropping circuit which drops the voltage of the battery power source to produce a dropped voltage, and a load circuit to drop the output voltage of the battery power source comprises a voltage switch circuit for supplying selectively the output voltage from the power source and the dropped voltage from the voltage dropping circuit to the logic circuit as a drive voltage. In the system, the logic circuit is usually operated by the output voltage from the dropping voltage circuit. When the load circuit operates, it is operated by the output voltage from the battery power source.

Abstract: An improved process for producing .gamma.-dicalcium silicate powder which is fine and has a uniform particle size. The .gamma.-dicalcium silicate power has a great ability to capture hydrogen halides and low hygroscopcity, and is useful as a stabilizer for halogen-containing synthetic resins and a filler for synthetic resins.