An Electronic Vertical Long-Period Seismometer

An experimental device has been developed which exhibits the characteristics of a vertical seismometer with a long natural period, the experimental device having demonstrated periods to 20 seconds. The device achieves long-period seismometer action through magnetic field support of the mass and electronic feedback. With suitable device parameters the performance equations will be of the same form as those of a conventional inertial seismometer, the natural period and damping being functions of an amplifier gain. There are other possible uses of the device principles, one being the construction of a stable table.