Abstract: Gas sensor materials composed of carbon mixture or metal-containing carbon mixture obtained as evaporated matter by arc discharge which occurs by passing an alternating current or a direct current with electric current density of 0.8 to 3.5 A/mm.sup.2 on discharge surfaces of carbon electrodes or metal-containing carbon electrodes in an inert gas under a pressure of 0.1 to 600 torr.

Abstract: A tape player with a built-in radio for a car, includes a station selection circuit and a tape scanning circuit. A single group of preset switches for selecting a desired station as well as a desired piece of music recorded on the tape is connected to both circuits. A change-over switch is provided for selectively changing over from one of the station selection circuit and tape scanning circuit, to the other. A switching circuit such as a gate circuit, for rendering one circuit inoperative and placing the other in a waiting state for operation in response to the change-over operation of the change-over switch, is also provided, so that manipulation of each preset switch of the group of preset switches, operates either the station selection circuit or the tape scanning circuit, which is kept in the waiting state for operation. The change-over switch is activated by loading a tape, to switch from the station selection circuit to the tape scanning circuit.