SEISMOMETRE Russian patent published in 2010 - IPC G01V1/16 

FIELD: physics.

SUBSTANCE: seismometre has a base on which two anti-parallel connected magnetic systems are mounted using two elastic supports and a support arm. The magnetic systems consist of series-connected cylindrical magnetic conductors, a permanent magnet and a pole terminal. A coil is put on a frame in the gap of the magnetic systems. The coil is connected to the output of a first amplifier. Two magnetic rods are attached to the base through a thread, coaxially with the longitudinal axis of the magnetic systems. The tapered ends of the magnetic rods are put into openings on the butt ends of the magnetic systems. A light-emitting diode and a double-area photodiode which make up an optical motion sensor are placed on the base. Output electrodes of the photodiode areas are connected to two inputs of the first amplifier respectively. A flat slit diaphragm is placed on magnetic conductors between the photodiode and the light-emitting diode The first magnetic rod is connected through a second reducing gear to a gear motor. The device also has a switch, a generator, a phase-sensitive rectifier, a low-pass filter, a limiter amplifier and a split non-magnetic bushing. The generator and the phase-sensitive rectifier are connected in series. The low-pass filter is connected through its input to the output of the phase-sensitive rectifier, and to the input of the gear motor through its output. The limiter amplifier, which is included in the device in order to convert output voltage from the optical motion sensor into rectangular pulses, is connected through its outputs to two inputs of the first amplifier and the second input of the phase-sensitive rectifier. The input of the switch is connected to the output of the generator and the output to the second input of the coil. The split non-magnetic bushing is rigidly attached by its ends to the first and second rods which are made from soft magnetic material.

EFFECT: increased accuracy of measurement due to use of a system for remote control of the natural period of the seismometre pendulum.

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