[in Japanese]

View full abstract

Stop watch is widely used as it can measure a comparatively short time accurately an dsimply. In the testing of watt-hour meters, the measurement of time is necessary and the accuracy of 0.1% has been aimed in 100 seconds measuring. But the error of stop watch is not less than 0.1 second for its mechanism.
As the electric stop watch drived by the constant frequency oscillator operates continuously, it has such advantages as high accuracy and low cost. It has been researched and put into practical use since many years ago, yet the time lags in its starting and stopping are pointed out as its defect. They are caused by the use of mechanical damper and bevel gear. Described in this paper, therefore, is the improvement of electric stop watch by using electric damper and simplified gear mechanism. In the improved watch, the time lags in starting and stopping are both about 0.01 second and the difference between them is oniy 0.002-0.005 second. In consequence, the resultant error is within ±0.05second. As to its aging, the result of some experiments shows that it can keep sufficient stability even in long-time use.

View full abstract

This paper describes a phase plane analysis of the step-function response of a secondary control system containing the non-linear dxmping a-b|e|, which varies with the magnitude of the error e. The system is represented by the non-linear differential equation ë+2(a-b|e|)è+ce=0.
In this paper, the emphasis is placed on the stability of the step-function response and by making use of phase plane, the critical value for the stability of the magnitude of the step input and the method for approximately calculating the value are given. Furthermore, these results are compared with those taken from the system which has the non-linear term in restoring force.

View full abstract

The change of electrical reSistance of some materials under the influence of a magnetic field, is known as a magnetoresistance effect. When a N-type germanium pellet as shown in Fig. 2 is placed in the magnetic field of 13, 000 gausses which is perpendicular to the direction of current, the resistance increases by about 20%.
The electric transducer of displacement, as illustrated in Fig. 9, consists of a magnet, which produces a uniform magnetic field between the poles, and two germanium pellets, with a half of each pellet being inside the magnetic field. When the pellets are moved together in right or left direction, the resistance of one pellet, which is inserted further into the magnetic fleld, increases and that of the other pellet less inserted decreases. Fig. 10 shows the measuring circuit of resistance change of magnetoresistors. When the constant voltage is supplied to the bridge as a power source, the output voltage of the bridge comes out proportionally to the displacement of the magnetoresistors. In actual circuit, a thermistor is used as a temperature compensator. The characteristics of this transducer are as follows:
Linearity error: less than 0.3% for 3.5mm displacement
Temperature error: less than 0.5% for 0 to 50°C change
Hysteresis: negligibly small
Figs. 23 and 24 show the diaphragm type differential pressure transmitter combined with electric displacement transducer applying magnetoresistance effect, which converts a differential pressure of 0-50″Aq. to 0-10mV D.C.

View full abstract