A high capacity adsorbent may be used for enriching oxygen concentration in an air stream. A rigid L-shaped terminal connected to one electrode of the power semiconductor is mounted on the base and extends upward and adjacent an edge of the printed circuit board. Opposite the light source is a light-receiving lens. Reflection means guides, to a converging optical system, light from that light source section whose reflector center axis is perpendicular to the direction of gravity. The program voltage supply adjusts the output program voltage based on the modeled voltage drop.