抄録
The result of applying the differential transformer of variable inductance type to the seismograph as a transducer proportional to displacement has been satisfactory.
The merits of the differential transformer are as follows:
1. It satisfies our requirement for linearity over a wide range of displacement.
2. As a seismograph it is compact in size and simple in design. The circuit for vacuum tubes is also simplified.
3. It is readily possible to increase the magnification to 105 by amplifier circuits.
Microtremors and microseisms have been recorded by attaching electrodynamic transducer (moving coil type) and differential transformer to the pendulum of a seismogrpah with a period of 1 second. In using the velocity seismograph (electrodynamic transducer attachment) with an integrating circuit hooked up to the amplifier circuit, at Hongo in Tokyo, when the time constant is raised to 4 sec., the results agree with those of displacement seismograph (differential transformer attachment).
