One type of oxygen meter was designed and tested in a power station. Though this work, it was found that some fundamental data on the meter is necessary to make a stable one. The principle of oxygen meter is based on an application of the fact that oxygen is a relatively strong paramagnetic gas. The magnetic wind of oxygen is made both by the strong heterogeneous magnetic field and heater located between pole pieces. By this wind the heater is cooled better than when there is no oxygen. The resistance variation caused by the cooling of the heater is detected from a change in resistance of the heater. As the material of the heater Pt is best, because, although it shows chemical activity at high temperatures, it is mild at temperature lower than about 290°C. As the result of measurement of distribution of magnetic flux density, it was found that B·dB/dz which is in direct proportion to the sensitivity of the meter sharply changes by its position. Relations between the sensitivity of the meter and magnetic flux density and between the temperature of the heater and room temperature were obtained. As the sensitivity is also in proportion to the square of the magnetic flux density, the latter should be kept strictly constant. To use the thermistor is one of the most effective methods to counteract the influence of room temperature. The most troublesome factor that affects not only the sensitivity but the 0 point of the meter is a change in supply voltage. To overcome it, a power circuit simple enough to satisfy users was suggested. Finally, the dynamic behavior of the meter was measured both by the indicial response method and frequency response method, and accordingly, the transfer functions G=exp(-3s)/(1+9.5s) and G=1/(1+2.5s)2 were obtained.

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This paper presents an analysis of the null voltage compensation of differential transformer which has been applied to the measurement of linear displacement.
A paralleled potentiometer, which has generally been used for null compensation, has not enough stability on zero position. The author has been pushing a study to minimize the zero shift caused by null compensation and has developed, as its result, another circuit which consists of a paralleled potentiometer and a small capacitor connected between the slide contact of the potentiometer and the neutral point of secondary coil of the differential transformer. With this new circuit, zero shift was reduced by approximately one eightieth from that of an ordinary circuit.

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同一周波数の正弦波交流2信号の位相差を比較測定する一方法として一方の信号の位相を推移せしめて他方と同位相として検出,調整した量-一般にこの場合機械的変化量で表わされる-によって電気的位相の推移量を間接的に測定する方法がある.このような場合に用いられるPhase Shifterとしてはすでに種々のものが報告されているが,比較的高い確度で,かつ360°におよぶ広範囲の推移を得るものは少ない.
シンクロ・レゾルバ(Synchro Resolver)を移相素子として用いたPhase Shifterはこの目的に応え得るのであるが,その動作状態,すなわち2個の固定子巻線に加える信号の電圧,および位相関係に適正を欠くと回転子の機械的回転角と出力信号の電気的移相角の関係は直線性を失う.これらは,電圧の差および位相の差,それぞれによって異なるがいずれも位相差の測定などの場合,大きな誤差の原因となる.

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